Anatomy Manual

Welcome to the comprehensive laboratory manual for the sequential 200-level human anatomy and physiology courses. This manual is designed to accompany your classroom lectures and serve as a guide for laboratory activities that will help you better understand the complexities of the human body.

Throughout this manual, you will find detailed explanations of each of the major systems in the human body. In addition to comprehensive explanations, this manual also includes laboratory activities that will allow you to explore each system in greater detail.

One of the most important components of this manual is the inclusion of dissection labs using fetal pigs. These labs will provide you with a hands-on opportunity to explore the anatomy and physiology of each system in detail. You will have the opportunity to examine the structures and functions of each system firsthand and gain a greater appreciation for the intricacies of the human body.

Along with the dissection and wet labs, this manual also includes a series of dry labs designed to gauge your understanding of each system. These labs will challenge you to apply what you have learned in the classroom and through the dissection labs to real-world scenarios. They will help you build your critical thinking and problem-solving skills and provide you with a deeper understanding of the material.

Images in this manual were taken of human cadavers, models, public domain, or used from other open educational resources (OER) such as OpenStax (images without attribution are public domain).  The images and labels used are directed towards a sequential 200-level course in human anatomy and physiology. 

We hope that this comprehensive laboratory manual will be a valuable resource for you as you progress through your courses in human anatomy and physiology. Whether you are pursuing a career in the medical field or simply have a strong interest in the human body, this manual will provide you with the knowledge and skills necessary to succeed.

Some labs are described using digital devices. Any analog to those devices will also work.  For example, the digital spirometer used in the lab can be substituted with a different digital, analog, or wet spirometer.

Anatomical Orientation

Histology

Integumentary System

Articulations (Joints)

Skeletal System

Muscular System

Nervous System: Nervous Tissue

Nervous System: Central Nervous System Anatomy

Nervous System: Peripheral Nervous System Anatomy

Cardiovascular System: Blood

Cardiovascular System: Heart

Cardiovascular System: Blood Vessels

Endocrine System

Lymphatic System

Respiratory System

Digestive System

Urinary System

Reproductive System

Developmental

Non-Consumable Items

·         General Laboratory Glassware

·         Compound Light Microscope

·         Microscope Slides

o    Human Histology Slides

o    Blood Slides

o    Endocrine Gland Slides

o    Lymphatic Slides

o    Digestive Slides

o    Empty Glass Slides

o    Coverslips

·         Bunsen Burner

·         Models

o    Complete human skeleton

o    Muscle

§  Head

§  Neck

§  Trunk

§  Arm

§  Leg

o    Brain

o    Brain Stem

o    Spinal Cord

o    Ear

o    Eye

o    Nose

·         Surface temperature thermometer

·         Electromyography Device

·         Reflex Hammer with accelerometer

·         3-lead Electroencephalography device

·         Electrocardiography Device

·         Sphygmomanometers

·         Stethoscopes

·         10 ml round bottom flask

·         Calorimeter

·         Clamp for flask

·         Clamp for thermometer

·         Wire Mesh

·         Thermometer

·         Stir rod

·         Graduated Cylinder, 10 mL

·         Bunsen burner

·         Electronic Balance

·         Spirometer

·         16 Test tubes

·         Ice Bath / Water bath ~ 5 Gallon Tub

·         Centrifuge tubes

·         Centrifuge

·         Camera (cellphone, tablet)

·         General PPE

Consumable Items

·         Stains

o    Crystal Violet

o    Gram’s Iodine

o    Safranin

o    Sedistain

·         Indicators

o    Benedict's reagent

o    Sudan III

o    Lugol's iodine solution

·         Ethanol

·         Alcohol swab

·         Sterile Cotton Tipped Applicators

·         Sterile urine collection container

·         DI Water

·         Preserved Specimen

o    Bovine Eyes

o    Fetal Pig

·         3 Dry Food Samples with Nutrition Labels

·         Aluminum Foil

·         Pipet

·         Full Dissection Kit

·         Dissection Tray (at least 40 cm)

·         Electrodes

·         Spirometer mouthpiece

·         1% Amylase solution

·         Albumin

·         NaOH solution

·         HCl solution

·         1% Starch solution

·         1% Pepsin solution

·         1% Lipase (pancreatin) solution

·         Heavy Cream

·         Bile salts

·         10-panel reagent strips

·         Artificial Blood (5 different types)

·         Artificial Blood antibodies

·         Blood Typing Wells

·         Toothpicks

This laboratory safety contract is designed to ensure the safety of all individuals participating in the anatomy lab. By signing this contract, you agree to follow all safety protocols and procedures outlined below.

General Lab Safety

I understand that laboratory work involves potential hazards and risks. I agree to follow all safety procedures and protocols to minimize the risk of injury or harm to myself and others.

·         I will always wear appropriate personal protective equipment (PPE) such as gloves, lab coats, goggles, and closed-toe shoes when working in the laboratory.

·         I will follow all posted laboratory rules and regulations and adhere to the instructor's instructions.

·         I will not eat, drink, or chew gum in the laboratory.

·         I will never touch or taste any chemicals or lab materials unless instructed to do so by the instructor.

·         I will always wash my hands with soap and water before and after working in the laboratory.

·         I will keep the laboratory clean and organized at all times, including disposing of waste materials properly.

·         I will report any accidents, injuries, or spills to the instructor immediately.

·         I will not perform any experiments or procedures that are not authorized by the instructor.

·         I will not engage in horseplay, pranks, or any behavior that could distract others or compromise safety.

·         I will always use caution when handling any lab equipment, and I will never attempt to repair or modify equipment without proper authorization and training.

·         I will follow proper procedures for handling and disposing of hazardous waste, including chemicals, biological materials, and sharps.

·         I will not bring any unauthorized materials or equipment into the laboratory.

Required PPE

I hereby agree to the following terms and conditions:

·         I will wear appropriate PPE as required by the instructor, including but not limited to:

o   Lab coat or apron to protect clothing

o   Safety goggles or face shield to protect eyes and face

o   Gloves to protect hands

o   Closed-toe shoes to protect feet

o   Long pants to protect legs

·         I understand that PPE must be worn at all times while in the laboratory, regardless of the activity being performed.

·         I will follow all laboratory safety guidelines provided by the instructor, including the proper handling and disposal of hazardous materials and the use of safety equipment.

·         I will report any accidents, incidents, or near-misses to the instructor immediately.

·         I understand that failure to follow safety guidelines or wear proper PPE may result in removal from the laboratory or disciplinary action.

·         I understand that laboratory safety is a shared responsibility and that I am accountable for the safety of myself and others in the laboratory.

 Dissection Safety

I agree to adhere to the following dissection safety guidelines and procedures while working in the laboratory:

·         I will wear appropriate PPE such as lab coats, gloves, and safety goggles to protect your skin and eyes.

·         I will ensure that all dissecting tools and equipment are properly sterilized before use.

·         I will use a dissecting tray with a non-slip surface and sharp dissection tools to avoid slipping and ensure clean cuts.

·         I will always handle specimens with care and respect. Never touch, smell or taste the specimen, and avoid contact with open wounds or broken skin.

·         I will keep the lab clean and organized by disposing of any waste or debris properly. Keep a biohazard container handy for disposing of any biological waste.

·         I will make sure you have good ventilation in the lab, especially if you are working with preservatives or other chemicals.

·         I will follow instructions carefully and do not deviate from the protocol. If you are unsure of what to do, seek guidance from your instructor or lab supervisor.

·         I will always wash your hands thoroughly with soap and water after handling any specimens or equipment.

·         I will clean my workstation thoroughly after the dissection is complete.

·         I will be cautious with sharp dissection tools and do not leave them lying around the lab. Dispose of them safely after use.

·         In case of any accidents or injuries, inform your lab supervisor immediately and seek medical attention if necessary.

Accident Procedures

I agree to adhere to the following safety guidelines and accident procedures while working in the laboratory:

·         I will notify the supervisor or the lab manager immediately.

·         I will secure the area and prevent further harm by turning off any equipment or power sources involved in the accident.

·         If there is a minor injury, I will provide first aid treatment as needed, such as cleaning and bandaging cuts or scrapes, or administering basic life support measures, if necessary.

·         In case of a serious injury, I will call for medical assistance immediately by dialing emergency services (911).

·         If there is a chemical spill or exposure, I will consult the instructor and the material safety data sheet (MSDS) and follow the appropriate procedures for the specific chemical.

·         If there is a fire, I will use the fire extinguisher to put out the flames, evacuate the area, and call 911.

·         I will report the incident to the lab supervisor and document the details of the accident, including the date, time, location, and nature of the incident, as well as any injuries sustained and the names of witnesses.

·         I will take corrective action to prevent incidents from occurring in the future.

Chemical Safety

·         I will not touch or taste any chemicals.

·         I will always wear appropriate personal protective equipment (PPE) such as lab coat, gloves, goggles, and face shields.

·         I will read and follow all instructions on chemical labels and Material Safety Data Sheets (MSDS) before using them.

·         I will store chemicals in appropriate containers, and label them correctly with the name of the chemical, date of receipt, expiration date, and hazard information.

·         I will not reuse pipettes, especially when transferring different chemicals.

·         I will keep chemicals in a well-ventilated area, away from sources of heat, sparks, and flame.

·         I will use fume hoods and other ventilation devices when working with volatile or toxic chemicals.

·         I will avoid working alone in the lab. Always have a lab partner or supervisor present.

·         I will dispose of chemicals and hazardous waste in accordance with local, state, and federal regulations.

·         I will know the location and proper use of emergency equipment, such as fire extinguishers, eye wash stations, and spill kits.

·         I will avoid eating or drinking in the lab, and wash hands thoroughly after working with chemicals.

·         I will report any accidents, spills, or injuries immediately to a supervisor or lab manager.

Lab Equipment Usage

·         I will not touch any equipment without the lab instructor's permission.

·         I will use equipment only for its intended purpose.

·         I will follow all operating instructions for equipment.

·         I will report any damaged equipment to the lab instructor immediately.

Here are some general procedures for using laboratory equipment commonly found in biology and anatomy labs:

·         Glassware: such as beakers, flasks, funnels, etc…

o   Cleaning: Thoroughly clean all glassware with soap and water before and after each use. Rinse with distilled water and dry using a lint-free cloth or air-dry.

o   Inspection: Inspect each piece of glassware before use for any cracks, chips, or other damage. Do not use any damaged glassware.

o   Measuring: Use graduated cylinders, pipettes, or burettes for accurate measurements of liquids. Always use the appropriate size and type of glassware for the volume of liquid you are measuring.

o   Mixing: Use a stirring rod or magnetic stir bar to mix liquids. Do not use any glassware to mix liquids that are not designed for that purpose.

o   Heating: Use a Bunsen burner or hot plate to heat glassware. Use a wire gauze mat to distribute the heat evenly and prevent direct contact between the glassware and the heat source.

o   Cooling: Use a beaker or flask filled with ice or cold water to cool glassware.

o   Transferring: Use a pipette, burette, or transfer pipette to transfer liquids between glassware. Avoid touching the glassware with the pipette tip or any other object. (DO NOT MOUTH PIPETTE)

o   Disposal: Dispose of all glassware according to your lab's protocols for hazardous waste disposal.

o   Storage: Store all glassware in a designated area, away from any heat sources or direct sunlight. Label all glassware with its intended use and keep it organized and easily accessible.

·         Microscopes: Before using a microscope, ensure that it is clean and properly adjusted. Adjust the focus and stage height as needed, and always use the lowest magnification to start. Use the stage controls to move the specimen and adjust the focus. Do not force any parts of the microscope or touch the lenses with your fingers.

·         Bunsen burner: Before lighting a Bunsen burner, ensure that the gas valve is open and the air intake is adjusted properly. Use a striker or match to light the burner, and adjust the flame as needed using the air intake. Never leave a lit Bunsen burner unattended, and always turn it off when finished.

·         Centrifuges: Load samples into centrifuge tubes or microcentrifuge tubes, being careful not to overfill them. Balance the tubes in the centrifuge and set the appropriate speed and time. Always wear appropriate personal protective equipment when using a centrifuge.

·         Balances: Calibrate the balance before use and ensure that it is properly zeroed. Place the object to be weighed on the balance and wait for the reading to stabilize. Use a clean spatula to handle the object and avoid touching it with your fingers.

·         Autoclaves: Load the autoclave with items to be sterilized and ensure that they are properly wrapped or packaged. Set the appropriate temperature and time for the cycle and start the autoclave. Follow all safety precautions, including wearing appropriate personal protective equipment.

·         Pipettes: Select the appropriate size pipette for the volume you need to measure. Insert the pipette tip into the liquid and slowly release the plunger to draw the liquid into the pipette. Dispense the liquid into the appropriate container, being careful not to touch the pipette tip to any surfaces.

·         pH meters: Calibrate the pH meter according to the manufacturer's instructions. Immerse the electrode in the solution to be measured and wait for the reading to stabilize. Rinse the electrode with distilled water between measurements.

·         Spectrophotometers: Prepare the sample according to the manufacturer's instructions and load it into a cuvette. Set the wavelength and adjust the sample compartment as needed. Record the absorbance reading and compare it to standards or controls.

Heating Safety

·         I will use hot plates and burners only for their intended purpose.

·         I will not touch hot plates, burners, or other hot surfaces.

·         I will allow equipment to cool before touching or moving it.

·         I will use appropriate protective gear, such as oven mitts, when handling hot equipment.

·         I will never leave heating equipment unattended.

·         I will use appropriate protective equipment, such as gloves, lab coats, and safety goggles, when working with heating equipment.

·         I will ensure that all heating equipment is in good working condition and properly grounded.

·         I will avoid overheating by regulating temperature and carefully monitoring the equipment.

·         I will keep flammable materials and liquids away from heating equipment.

·         I will follow all manufacturer instructions for operating and maintaining heating equipment.

·         I will familiarize yourself with the emergency procedures in case of accidents, such as fire or burns.

·         I will always turn off heating equipment after use and unplug it from the outlet.

·         I will store heating equipment in a safe and secure location when not in use.

·         I will keep the work area clean and organized to prevent accidents and ensure safe use of heating equipment.

If there are physical, medical, mental, emotional, religious, or other concern about a chemical, lab practice, experiment, etc. notify the instructor as soon as possible.  Health issues are taken seriously, to avoid harm to the student.  You are not required to volunteer personal information, but it may improve the assistance received (i.e.: if a student is pregnant but doesn’t relay this information to the instructor, they may not be alerted to certain chemicals that could to harmful during pregnancy.  Or, if a student is allergic to penicillin and doesn’t inform the instructor they may not be aware of the usage of penicillin in some labs). 

Abdominal Cavity: The space within the abdomen that contains various organs such as the stomach, liver, and intestines.

Abdominal Region: A specific area on the abdomen, often used to describe the location of various organs or structures.

Abdominopelvic Cavity: The combined space formed by the abdominal and pelvic cavities.

Abdominopelvic Quadrants: Four regions of the abdominopelvic cavity, divided by imaginary lines intersecting at the umbilicus (navel), used to locate and describe organs within the cavity.

Abdominopelvic Regions: Nine regions of the abdominopelvic cavity, determined by two horizontal and two vertical lines, used to describe the location of various organs.

Abducens Nerve: The sixth cranial nerve, responsible for controlling the movement of the lateral rectus muscle, which abducts the eye.

Abduction: The movement of a body part away from the midline of the body or the axial line of a limb.

Abo System: A system of blood group antigens, including A, B, and O, that determine blood types.

Accessory Nerve: The eleventh cranial nerve, also known as the spinal accessory nerve, which controls the movement of certain neck and shoulder muscles.

Acetylcholine: A neurotransmitter involved in various functions, including muscle movement, memory, and autonomic nervous system regulation.

Acromial: Relating to the acromion, the bony process at the top of the shoulder blade.

Acrosome Reaction: The process by which the acrosome, a structure in the head of a sperm cell, releases enzymes to penetrate the protective layer of an egg.

Actin: A protein involved in muscle contraction and cell movement.

Action Potentials: Brief electrical impulses that transmit signals within nerve cells and between nerve cells and muscles or glands.

Adduction: The movement of a body part toward the midline of the body or the axial line of a limb.

Adipose: Relating to fat or fatty tissue.

Adipose Tissue: A type of connective tissue that stores energy in the form of fat cells.

Adrenal Glands: Endocrine glands located on top of the kidneys that produce hormones such as adrenaline, cortisol, and aldosterone.

Adrenocorticotropic Hormone (ACTH): A hormone produced by the anterior pituitary gland that stimulates the adrenal cortex to release cortisol.

Afferent Arteriole: A small artery that carries blood from the main artery to a network of capillaries within a tissue or organ.

Afterload: The resistance that the heart must overcome to eject blood during contraction.

Alveolar Ducts: Small ducts within the lungs that connect the respiratory bronchioles to the alveolar sacs.

Alveoli: Tiny air sacs in the lungs where gas exchange occurs between the air and blood.

Amphiarthrosis: A slightly movable joint, such as the symphysis pubis or the intervertebral joints.

Amygdala: A part of the brain involved in processing emotions, particularly fear and aggression.

Amylase: An enzyme that breaks down complex carbohydrates into simpler sugars, produced in the salivary glands and pancreas.

Anatomical Position: The standard reference position for describing the human body, with the body standing erect, arms at the sides, and palms facing forward.

Antebrachial: Relating to the forearm, which extends from the elbow to the wrist.

Anterior: Referring to the front or the direction toward the front of the body.

Anterior Pituitary: The front portion of the pituitary gland that produces and releases several hormones that regulate various bodily functions.

Antidiuretic Hormone (ADH): A hormone produced by the posterior pituitary gland that regulates water balance by controlling the reabsorption of water in the kidneys.

Antigen-Presenting Cells: Cells, such as macrophages and dendritic cells, that display foreign antigens to activate the immune response.

Anus: The opening at the end of the digestive tract through which solid waste is eliminated from the body.

Aorta: The main artery of the body, originating from the left ventricle of the heart and distributing oxygenated blood to all parts of the body.

Aortic Semilunar Valve: A heart valve located between the left ventricle and the aorta that prevents backflow of blood from the aorta into the heart.

Apocrine: A type of glandular secretion characterized by the release of cytoplasm along with the secretory product.

Appendicular Skeleton: The portion of the skeleton that includes the bones of the limbs and their associated girdles.

Appendix: A small, finger-like projection attached to the cecum, which is a part of the large intestine.

Aqueous Body: A fluid-filled chamber in the eye located between the cornea and the lens, involved in maintaining the shape of the eyeball and nourishing the surrounding structures.

Arachnoid Mater: The middle layer of the meninges, which are the protective coverings of the brain and spinal cord.

Areolar Tissue: A type of loose connective tissue that fills spaces between organs and provides support to surrounding structures.

Arteries: Blood vessels that carry oxygenated blood away from the heart to various parts of the body.

Arterioles: Small branches of arteries that further divide into capillaries.

Articular Cartilage: A thin layer of hyaline cartilage that covers the surfaces of bones where they form joints, reducing friction and absorbing shock.

Articulations: Joints where two or more bones come together, allowing for movement and providing stability.

Ascending Colon: The portion of the large intestine that extends upward from the cecum.

Astrocytes: Star-shaped glial cells in the central nervous system that provide structural and metabolic support to neurons.

ATP: Adenosine triphosphate, the primary energy currency of cells.

Atria: The two upper chambers of the heart (left and right atrium) that receive blood returning to the heart.

Atrioventricular Node: A specialized group of cells located in the heart between the atria and the ventricles, responsible for transmitting electrical signals that regulate the heartbeat.

Autonomic Nervous System: The part of the peripheral nervous system that controls involuntary functions, such as heart rate, digestion, and breathing.

Axial Skeleton: The central framework of the skeletal system, including the skull, vertebral column, and thoracic cage.

Axillary: Relating to the armpit region or the axilla.

B Lymphocytes: A type of white blood cell involved in the immune response, responsible for producing antibodies.

Ball-And-Socket: A type of joint where a spherical end of one bone fits into a socket-like cavity of another bone, allowing for a wide range of motion. Examples include the hip and shoulder joints.

Basal Metabolic Rate (BMR): The rate at which the body uses energy at rest to maintain vital functions, such as breathing and maintaining body temperature.

Basophils: A type of white blood cell involved in allergic reactions and inflammation, releasing histamine and other chemical mediators.

Bicarbonate: An ion (HCO3-) involved in regulating the pH balance of the blood and other body fluids.

Bicuspid: Referring to a structure with two cusps or points, such as the bicuspid valve in the heart, also known as the mitral valve.

Bile: A fluid produced by the liver and stored in the gallbladder that aids in the digestion and absorption of fats.

Bile Duct: A tube that carries bile from the liver and gallbladder to the small intestine.

Blastocyst: An early stage of embryonic development, consisting of a hollow ball of cells, formed after the morula stage.

Blood: A specialized bodily fluid that circulates through the cardiovascular system, carrying oxygen, nutrients, hormones, and waste products.

Blood-Brain Barrier: A selective barrier formed by the endothelial cells of the brain's capillaries, which prevents certain substances in the blood from entering the brain tissue.

Blood Plasma: The liquid component of blood, mainly composed of water, proteins, electrolytes, hormones, and dissolved substances.

Blood Pressure: The force exerted by circulating blood on the walls of blood vessels, measured in millimeters of mercury (mmHg).

Blood Typing: The process of determining a person's blood type, usually based on the presence or absence of certain antigens on red blood cells.

Blood Vessels: Tubes that carry blood throughout the body, including arteries, veins, and capillaries.

Bone: A type of connective tissue that forms the skeletal system, providing support, protection, and facilitating movement.

Bone Lining Cells: Cells that cover the surface of bones, playing a role in bone remodeling and maintenance.

Bone Marrow: A soft tissue found inside certain bones, responsible for the production of blood cells (red blood cells, white blood cells, and platelets).

Bony Fusion: The joining or fusion of bones, typically occurring during development or as a result of certain conditions or injuries.

Bowman's Capsule: A cup-shaped structure in the kidney that surrounds the glomerulus and participates in the filtration of blood to form urine.

Brachial: Relating to the arm, specifically the upper arm between the shoulder and elbow.

Brain Stem: The lower part of the brain that connects the spinal cord to the cerebrum, comprising the medulla oblongata, pons, and midbrain. It regulates vital functions such as breathing, heart rate, and consciousness.

Bronchi: The main branches of the trachea that lead into the lungs, further dividing into smaller bronchioles.

Bronchomediastinal Trunk: Lymphatic vessels that drain lymph from the bronchi and mediastinal structures, contributing to the immune system.

Buffy Coat: The middle layer of centrifuged blood, consisting of white blood cells and platelets.

Bulbourethral Gland: Also known as Cowper's gland, a pair of exocrine glands in males that secrete a lubricating fluid into the urethra during sexual arousal.

Bundle Of His: A specialized group of cardiac muscle fibers that conduct electrical impulses from the atria to the ventricles in the heart's conduction system.

Calcaneus: The largest tarsal bone in the foot, commonly known as the heel bone.

Calcitonin: A hormone produced by the thyroid gland that helps regulate calcium levels in the blood by promoting calcium deposition in bones.

Calcium: An essential mineral involved in various physiological processes, including bone formation, muscle contraction, and nerve function.

Canaliculi: Microscopic channels or tubules in bone tissue that connect lacunae, allowing for the exchange of nutrients and waste products between osteocytes.

Capillaries: Tiny, thin-walled blood vessels that connect arterioles and venules, facilitating the exchange of nutrients, gases, and waste products between blood and surrounding tissues.

Capitate: One of the carpal bones in the wrist, located between the trapezoid and the hamate.

Carbohydrates: A group of macronutrients that serve as a primary source of energy in the body, including sugars, starches, and fibers.

Cardiac Muscle Tissue: Specialized muscle tissue found in the walls of the heart, responsible for the contraction and pumping of blood.

Cardiac Output: The volume of blood pumped by the heart per unit of time, typically measured in liters per minute.

Cardiovascular System: The organ system responsible for the circulation of blood throughout the body, consisting of the heart, blood vessels, and blood.

Carpal: Relating to the eight carpal bones in the wrist.

Carpals: The group of eight bones that make up the wrist, connecting the forearm to the hand.

Cartilage: A flexible connective tissue found in various parts of the body, providing support, cushioning, and shaping of certain structures.

Cartilaginous: Referring to a joint or structure that is connected by cartilage, allowing limited movement.

Cavities: Hollow spaces or body cavities that contain organs, such as the thoracic cavity, abdominal cavity, or cranial cavity.

Cecum: The pouch-like structure that connects the small intestine to the large intestine, involved in the absorption of water and electrolytes.

Cell: The basic structural and functional unit of all living organisms.

Cellular Respiration: The process by which cells convert nutrients into energy in the form of ATP, typically involving the consumption of oxygen and production of carbon dioxide.

Central Nervous System: The part of the nervous system that includes the brain and spinal cord, responsible for processing and coordinating sensory information and controlling body functions.

Cerebellum: The part of the brain located at the back of the skull, responsible for coordinating voluntary movements, balance, and posture.

Cerebrum: The largest part of the brain, divided into two hemispheres, responsible for higher cognitive functions, sensory processing, and motor coordination.

Cervical Region: Referring to the region of the body that includes the neck and the first seven vertebrae of the spine (cervical vertebrae).

Cervical Vertebrae: The seven vertebrae in the neck region of the spine, labeled C1 to C7.

Cervix: The lower part of the uterus that connects to the vagina, involved in the menstrual cycle and childbirth.

Cheeks: The fleshy area on the sides of the face, formed by the buccinator muscles.

Chloride: An electrolyte and essential mineral that plays a role in maintaining fluid balance, pH regulation, and nerve function.

Choroid: A vascular layer of the eye located between the retina and the sclera, providing nourishment to the retina.

Chromium: A trace mineral that plays a role in glucose metabolism and the action of insulin.

Cilia: Tiny, hair-like structures found on the surface of certain cells, responsible for movement and the transportation of substances.

Ciliary Body: A part of the eye located between the iris and the choroid, involved in the production of aqueous humor and accommodation of the lens.

Cingulate Gyrus: A region of the cerebral cortex involved in emotions, learning, and memory.

Circumduction: A type of joint movement that involves a circular or cone-shaped motion, combining flexion, extension, abduction, and adduction.

Circumvallate Papillae: Large, circular papillae on the back of the tongue that contain taste buds.

Cisterna Chyli: A lymphatic sac located in the abdomen that serves as a storage area for lymph before it enters the bloodstream.

Clavicle: A bone that connects the shoulder blade (scapula) to the sternum, commonly known as the collarbone.

Clitoral Hood: A fold of skin that covers and protects the clitoris in females.

Clitoris: A highly sensitive erectile organ located above the vaginal opening in females, involved in sexual arousal.

Closed Fractures: Fractures in which the bone is broken but does not penetrate the skin.

Coccyx: The small triangular bone at the base of the spine, commonly referred to as the tailbone.

Cochlea: A spiral-shaped, fluid-filled structure in the inner ear responsible for converting sound vibrations into electrical signals that can be interpreted by the brain.

Collecting Duct: A tubular structure in the kidney that receives urine from multiple nephrons and plays a role in water reabsorption.

Commuted Fractures: Fractures in which the bone is fragmented or broken into multiple pieces.

Compact Bone: Dense bone tissue that forms the outer layer of bones, providing strength and protection.

Compacted Fractures: Fractures in which the broken ends of a bone are forcefully driven into each other.

Complete Fractures: Fractures in which the bone is completely broken into two or more separate pieces.

Condyloid: Referring to a joint that allows movement in two directions, such as the wrist joint.

Conjunctiva: A thin, transparent membrane that covers the front surface of the eye and lines the inside of the eyelids.

Connective Tissue: A type of tissue that connects, supports, and protects other tissues and organs in the body, including bone, cartilage, blood, and adipose tissue.

Continuous Capillaries: The most common type of capillaries that form a continuous, uninterrupted lining, allowing for the exchange of small molecules and cells.

Contralateral: Relating to the opposite side of the body or referring to structures on the opposite sides.

Copper: A trace mineral that plays a role in the formation of red blood cells, energy production, and connective tissue synthesis.

Cornea: The transparent, dome-shaped front surface of the eye that helps focus light onto the retina.

Corona Radiata: A layer of cells that surrounds the oocyte (egg cell) in the ovary and helps nourish and support its development.

Corpus Albicans: A structure that forms in the ovary after ovulation if fertilization does not occur, representing the regressed corpus luteum.

Corpus Callosum: A thick bundle of nerve fibers that connects the left and right hemispheres of the brain, allowing for communication and coordination between them.

Corpus Cavernosum Clitoris: The paired erectile tissue in the clitoris that becomes engorged with blood during sexual arousal.

Corpus Cavernosum Penis: The paired erectile tissue in the penis that becomes engorged with blood during an erection.

Corpus Luteum: A temporary endocrine structure that forms in the ovary after ovulation, secreting hormones such as progesterone to support pregnancy.

Corpus Spongiosum: The erectile tissue in the penis that surrounds the urethra and helps maintain the rigidity of the penis during an erection.

Cortical Reaction: A series of biochemical changes that occur in the egg immediately after fertilization to prevent the entry of additional sperm.

Counter Current Mechanism: A mechanism in the kidney that allows for efficient reabsorption of water and solutes by creating a concentration gradient along the nephron tubules.

Coxal: Referring to the hip or hip joint.

Cranial Bones: The bones that form the cranium or skull, protecting the brain. They include the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones.

Cranial Cavity: The space within the skull that houses and protects the brain.

Cranial Nerves: The twelve pairs of nerves that originate from the brain and are involved in sensory, motor, and autonomic functions of the head and neck.

Cranial Region: Referring to the region of the body that includes the head and skull.

Cross-Bridges: Structures formed between actin and myosin filaments in muscle fibers during contraction, allowing for the sliding of filaments.

Cuboid: One of the tarsal bones in the foot, located on the outer side of the foot, distal to the calcaneus.

Cuneiforms: A group of three tarsal bones in the foot, located between the metatarsals and the navicular bone. They are named the medial cuneiform, intermediate cuneiform, and lateral cuneiform.

Deep: Referring to a location that is farther away from the surface or outside of the body.

Dendritic Cells: Immune cells that play a crucial role in antigen presentation, capturing pathogens or foreign substances and presenting them to other immune cells to initiate an immune response.

Depolarization: The change in membrane potential of a cell, typically a neuron or muscle cell, where the inside becomes less negative or even positive, leading to the generation of an action potential.

Depression Fractures: Fractures in which a portion of bone is pushed inward, causing a depression or indentation in the bone surface.

Dermis: The thick, inner layer of the skin located beneath the epidermis, containing blood vessels, nerves, hair follicles, and sweat glands.

Descending Colon: The portion of the large intestine that extends downward on the left side of the abdomen, connecting the transverse colon to the sigmoid colon.

Developmental System: The biological processes and events that occur during the growth and maturation of an organism, including embryonic development, fetal development, and postnatal growth.

Diaphragm: A dome-shaped muscle located below the lungs that plays a key role in breathing by contracting and relaxing to change the volume of the thoracic cavity.

Diarthrosis: A type of freely movable joint characterized by a joint cavity and articular cartilage, allowing for a wide range of movement. Examples include the shoulder and knee joints.

Diastolic: Referring to the phase of the cardiac cycle when the heart muscle relaxes and fills with blood, typically associated with a lower blood pressure reading.

Diastolic Pressure: The pressure exerted by blood against the walls of arteries during diastole, representing the lower number in a blood pressure reading (e.g., 120/80, where 80 is the diastolic pressure).

Diencephalon: The region of the brain located between the cerebral hemispheres and the brainstem, consisting of structures such as the thalamus, hypothalamus, and pineal gland.

Digestion: The process of breaking down food into smaller molecules that can be absorbed and used by the body.

Digestive System: The organ system responsible for the breakdown, absorption, and processing of food, including organs such as the mouth, esophagus, stomach, intestines, liver, and pancreas.

Directional Terms: Terms used to describe the relative positions or locations of body structures, such as superior (above), inferior (below), anterior (front), posterior (back), medial (towards the midline), lateral (away from the midline), proximal (closer to the point of attachment), and distal (farther from the point of attachment).

Displaced Fractures: Fractures in which the broken ends of a bone are no longer in their normal anatomical alignment.

Distal: Referring to a location that is farther away from the point of attachment or reference.

Distal Convoluted Tubule: A segment of the renal tubule in the kidney responsible for the reabsorption of water and electrolytes and the secretion of waste products.

Distal Nail Fold: The skin fold located at the base of the nail plate on the side farthest from the center of the digit.

DNA: Deoxyribonucleic acid, a molecule that contains genetic instructions for the development and functioning of all living organisms.

Dopamine: A neurotransmitter involved in various functions such as movement, reward, motivation, and pleasure. It plays a critical role in the brain's reward system.

Dorsal Cavities: Body cavities located along the posterior (dorsal) side of the body, including the cranial cavity (housing the brain) and the vertebral or spinal cavity (housing the spinal cord).

Dorsiflexion: The movement that involves flexing the foot upward towards the shin, reducing the angle between the foot and the leg.

Duodenum: The first segment of the small intestine, connecting the stomach to the jejunum, where further digestion of food and absorption of nutrients occur.

Eccrine: Referring to sweat glands that are distributed throughout the body and secrete sweat onto the skin surface to regulate body temperature.

Efferent Arteriole: A small blood vessel that carries blood away from the glomerulus of the kidney nephron, playing a role in blood filtration and urine formation.

Elastic Arteries: Large arteries that are rich in elastic fibers, allowing them to stretch and recoil to accommodate the pulsatile flow of blood from the heart.

Elastic Cartilage: A type of cartilage found in areas requiring flexibility and resilience, such as the external ear and the epiglottis.

Elastic Connective Tissue: Connective tissue composed of elastic fibers that provide elasticity and stretchability to tissues and organs, such as the walls of blood vessels and certain ligaments.

Electrocardiogram: A diagnostic test that records the electrical activity of the heart, used to evaluate heart rhythm, identify abnormalities, and assess cardiac health.

Embryoblast: The inner cell mass of the blastocyst that gives rise to the embryo.

Embryonic Development: The process of growth and differentiation of cells and tissues that occurs after fertilization and leads to the formation of an embryo.

End Motor Plate: The specialized region where the motor neuron synapses with a muscle fiber, initiating muscle contraction.

Endocrine: Referring to glands or cells that secrete hormones directly into the bloodstream to regulate various bodily functions.

Endocrine System: The system of glands and cells that produce and secrete hormones, coordinating and regulating processes such as growth, metabolism, reproduction, and stress response.

Endorphins: Neurotransmitters produced by the central nervous system that act as natural painkillers and contribute to feelings of pleasure and well-being.

Enzyme: A biological catalyst that facilitates chemical reactions in living organisms.

Eosinophils: A type of white blood cell involved in the immune response, particularly in combating parasitic infections and modulating allergic reactions.

Ependymal Cells: Cells that line the ventricles of the brain and the central canal of the spinal cord, involved in the production and circulation of cerebrospinal fluid.

Epidermis: The outermost layer of the skin composed of stratified squamous epithelium, providing protection and serving as a barrier against pathogens, UV radiation, and water loss.

Epididymis: A coiled tubular structure located on the posterior surface of each testis, where sperm cells mature and are stored before ejaculation.

Epigastric Region: The upper central region of the abdomen, located between the left and right hypochondriac regions.

Epiphyseal Fractures: Fractures that occur at the epiphyseal plate or growth plate of a long bone, typically affecting growing children and adolescents.

Epithalamus: A region of the diencephalon that includes the pineal gland and is involved in the regulation of sleep-wake cycles and certain endocrine functions.

Epithelial Tissue: Tissue composed of closely packed cells that line body surfaces, cavities, and glands, serving protective, absorptive, secretory, and sensory functions.

Eponychium: The narrow band of tissue at the base of the nail that overlaps the proximal nail fold, also known as the cuticle.

Equilibrium: The state of balance or stability, particularly referring to the sense of balance and spatial orientation.

Erythroblastosis Fetalis: A condition in which maternal antibodies against fetal red blood cells cross the placenta, leading to destruction of fetal red blood cells and potentially causing severe anemia in the fetus.

Erythrocytes: Red blood cells, the most common type of blood cell responsible for transporting oxygen to tissues and removing carbon dioxide.

Esophagus: A muscular tube that connects the throat (pharynx) to the stomach, allowing the passage of food and liquids during swallowing.

Ethmoid Bone: A bone located in the skull between the eyes, contributing to the nasal cavity, eye sockets, and the roof of the nasal septum.

Ethmoid Sinuses: Air-filled spaces within the ethmoid bone, located between the eyes and behind the bridge of the nose, playing a role in the production of mucus and the resonance of the voice.

Etymology: The study of the origin and history of words, including their formation, development, and changes in meaning over time.

Eversion: The movement of turning a body part outward or away from the midline, such as turning the sole of the foot outward.

Expiratory Reserve Volume: The additional volume of air that can be forcibly exhaled after a normal exhalation.

Extension: The movement that increases the angle between two body parts or straightens a joint, typically moving away from a flexed or bent position.

External Acoustic Meatus: The canal in the outer ear that leads to the eardrum, also known as the ear canal.

External Respiration: The exchange of oxygen and carbon dioxide between the lungs and the external environment, typically occurring in the alveoli of the lungs.

Eye: The organ of vision, responsible for detecting and processing visual information. It consists of various structures, including the cornea, iris, lens, retina, and optic nerve.

Facial Bones: Bones that make up the structure of the face, including the maxilla, mandible, nasal bones, zygomatic bones, and others.

Facial Nerve: The seventh cranial nerve that innervates the muscles of facial expression and controls functions such as facial movements, taste sensation on the anterior two-thirds of the tongue, and tear production.

Facial Plane: An imaginary plane passing through the face, dividing the body into anterior and posterior sections.

Facial Region: The area of the head that includes the face, including the forehead, eyes, nose, mouth, and chin.

Fallopian Tubes: Also known as uterine tubes or oviducts, these are a pair of tubes in the female reproductive system that connect the ovaries to the uterus, allowing for the transport of eggs and the site of fertilization.

False Ribs: The lower five pairs of ribs that do not directly attach to the sternum but instead attach to the cartilage of the rib above.

Female Reproductive System: The reproductive system in females, consisting of organs such as the ovaries, fallopian tubes, uterus, vagina, and external genitalia, involved in the production of eggs, fertilization, pregnancy, and childbirth.

Femoral: Referring to the femur or thigh region.

Femur: The largest and longest bone in the human body, located in the thigh, and forming the hip and knee joints.

Fenestrated Capillaries: Capillaries with small pores or openings in their walls, allowing for the exchange of small molecules and fluids between the blood and surrounding tissues.

Fertilization: The process of union of a sperm and an egg to form a zygote, typically occurring in the fallopian tubes.

Fertilization Envelope: A protective envelope or membrane formed around the zygote following fertilization, preventing additional sperm from entering and ensuring the integrity of the developing embryo.

Fetal Stage: The stage of prenatal development from the ninth week after fertilization until birth, during which the developing organism is called a fetus.

Fibrocartilage: A type of cartilage found in structures such as intervertebral discs and the pubic symphysis, characterized by its ability to withstand pressure and tension due to the presence of both collagen fibers and cartilage cells.

Fibrous: Referring to tissue composed of or resembling fibers, such as fibrous connective tissue or fibrous joints.

Fibrous Pericardium: The tough outer layer of the pericardium, the double-layered sac surrounding the heart, providing protection and anchoring the heart within the chest cavity.

Fibula: The slender bone located on the lateral side of the lower leg, parallel to the tibia, playing a role in support and muscle attachment.

Filiform Papillae: Tiny, threadlike papillae on the surface of the tongue, responsible for tactile sensation and not involved in taste perception.

Flat Bones: Bones with a flat and usually thin shape, such as the bones of the skull, sternum, and ribs.

Flexion: The movement that decreases the angle between two body parts or bends a joint, typically bringing body parts closer together.

Floating Ribs: The last two pairs of ribs that do not attach directly to the sternum or cartilage of other ribs, but instead "float" in the posterior portion of the rib cage.

Fluoride: A mineral that is important for dental health and the prevention of tooth decay, commonly added to drinking water and toothpaste.

Follicle-Stimulating Hormone: A hormone released by the anterior pituitary gland that stimulates the growth and development of follicles in the ovaries and promotes the production of sperm in the testes.

Formed Elements: The cellular components of blood, including red blood cells, white blood cells, and platelets.

Free Nerve Endings: Nerve endings that are unencapsulated and widely distributed throughout tissues, responsible for detecting pain, temperature, and touch sensations.

Frequency: The number of occurrences of a repeating event within a given time period, often used to describe the pitch of sound waves.

Frontal Bone: The bone that forms the forehead and the upper part of the eye sockets, contributing to the structure of the cranium.

Frontal Lobe: The largest lobe of the brain, located at the front of the cerebral cortex, involved in functions such as motor control, decision-making, problem-solving, and personality.

Frontal Plane: An imaginary plane that divides the body into front and back portions, also known as the coronal plane.

Frontal Sinuses: Air-filled spaces located within the frontal bone of the skull, playing a role in reducing the weight of the skull and providing resonance to the voice.

Fungiform Papillae: Mushroom-shaped papillae found on the surface of the tongue, containing taste buds and involved in the perception of taste.

Gallbladder: A small organ located beneath the liver that stores and concentrates bile produced by the liver, releasing it into the small intestine to aid in digestion.

Gamma-Aminobutyric Acid (GABA): An inhibitory neurotransmitter in the central nervous system that helps regulate neuronal excitability and plays a role in reducing anxiety and promoting relaxation.

Gastrulation: The process during early embryonic development in which the single-layered blastula transforms into a three-layered structure known as the gastrula, forming the basic body plan of the organism.

Glans Penis: The rounded tip or head of the penis, highly sensitive to touch and involved in sexual stimulation.

Glomerular Apparatus: The specialized structure within the kidney responsible for the filtration of blood and the formation of urine, consisting of the glomerulus, Bowman's capsule, and associated tubules.

Glomerulus: A network of tiny blood vessels (capillaries) within the kidney's nephron where filtration of blood occurs, forming the initial step in urine formation.

Glossopharyngeal Nerve: The ninth cranial nerve responsible for the sense of taste from the posterior one-third of the tongue, as well as other functions such as swallowing and monitoring blood pressure.

Glutamate: An excitatory neurotransmitter in the central nervous system that plays a key role in synaptic transmission and is involved in learning, memory, and various neurological processes.

Gomphoses: Immovable joints found between teeth and their sockets in the maxilla and mandible, providing stability and support to the teeth.

Greater Vestibular Glands: Glands located on either side of the vaginal opening in females, responsible for producing lubrication during sexual arousal.

Greenstick Fractures: Incomplete fractures in which the bone is partially bent and partially broken, commonly seen in children due to the flexibility of their bones.

Growth Hormone: A hormone released by the anterior pituitary gland that promotes growth and development in various tissues and organs of the body.

Gustatory Cells: Specialized cells found within taste buds on the tongue and oral cavity, responsible for detecting and transmitting taste sensations to the brain.

Hair: A filamentous structure made of keratin that grows from follicles found in the skin, serving various functions such as protection, insulation, and sensory perception.

Hamate: One of the carpal bones located on the ulnar side of the wrist, contributing to the structure of the palm and the movement of the hand.

Haversian Canal: Microscopic channels found in compact bone that contain blood vessels, nerves, and connective tissue, allowing for the exchange of nutrients and waste products.

Haversian System (Osteon): The basic structural unit of compact bone, consisting of concentric rings of bone matrix called lamellae surrounding a central Haversian canal.

Head: The uppermost part of the body that contains the brain, sensory organs, and various structures such as the face and skull.

Hearing: The sense of perceiving sound waves and interpreting them as auditory information, involving the structures of the ear and the processing of sound by the auditory system.

Heart: A muscular organ responsible for pumping blood throughout the body, consisting of four chambers (two atria and two ventricles) and various valves.

Hematocrit: The percentage of red blood cells in the total volume of blood, often used as a measure of blood cell composition and the diagnosis of certain conditions.

Hinge: A type of synovial joint that allows movement in only one plane, resembling the action of a hinge, such as the elbow joint.

Hippocampus: A region of the brain located within the temporal lobe, playing a crucial role in learning, memory formation, and spatial navigation.

Histology: The study of the microscopic structure of tissues and organs, examining their cellular composition and organization.

Homeostasis: The ability of an organism to maintain a stable internal environment despite external changes.

Hormonal Stimulus: A type of stimulus that triggers the release of hormones from endocrine glands, initiating various physiological responses and regulating bodily functions.

Hormone: Chemical messenger produced by endocrine glands that is released into the bloodstream and act on target cells or organs, regulating various physiological processes and maintaining homeostasis.

Humerus: The bone of the upper arm or forelimb, connecting the shoulder joint to the elbow joint and playing a role in arm movement and support.

Humoral Stimulus: A type of stimulus that triggers the release of hormones in response to changes in blood levels of certain substances or ions, such as glucose or calcium.

Hyaline Cartilage: A type of cartilage with a smooth and glassy appearance, found in structures such as the joints, respiratory passages, and developing long bones.

Hypertension: A condition characterized by persistently elevated blood pressure, often associated with increased risk of cardiovascular diseases.

Hyperthyroidism: A condition characterized by excessive production of thyroid hormones by the thyroid gland, resulting in symptoms such as increased metabolism, weight loss, and nervousness.

Hypochondriac Region: One of the nine divisions of the abdomen, located on the left and right sides below the ribcage, often used in clinical diagnosis to describe the location of abdominal pain or organ involvement.

Hypogastric Region: One of the nine divisions of the abdomen, located in the lower middle portion, also known as the pubic region or lower abdominal region.

Hypoglossal Nerve: The twelfth cranial nerve responsible for controlling the muscles of the tongue and playing a role in speech and swallowing.

Hyponychium: The area of skin located beneath the free edge of the nail, forming a seal between the nail plate and the fingertip.

Larynx: The voice box, is a structure made of cartilage connecting the pharynx to the trachea. It contains the vocal folds which are responsible for producing sound.

Ileocecal Valve: A valve located between the ileum and the cecum, regulating the flow of digested material from the small intestine to the large intestine.

Ileum: The final and longest section of the small intestine, responsible for the absorption of nutrients from digested food.

Iliac Region: One of the nine divisions of the abdomen, located on the left and right sides of the lower abdomen, near the iliac bones.

Ilium: The large, flaring bone forming the upper part of the hip bone, contributing to the pelvic girdle and providing attachment for several muscles.

Immune System: The body's defense system against pathogens and foreign substances.

Incomplete Fractures: Fractures in which the bone is partially cracked or broken, but the fragments remain partially joined, often resulting in a hairline fracture.

Incontinence: The inability to control the release of urine or feces, leading to involuntary leakage.

Incus: One of the three small bones in the middle ear, also known as the anvil, transmitting sound vibrations from the malleus (hammer) to the stapes (stirrup).

Inferior: Referring to a position or structure that is situated below or lower in location compared to another structure or reference point.

Inguinal Region: The area of the body located in the lower abdomen where the thigh meets the torso, often referred to as the groin area.

Inspiratory Reserve Volume: The additional volume of air that can be inhaled forcefully after a normal inhalation.

Insular Lobe: A region of the cerebral cortex located deep within the lateral sulcus of the brain, playing a role in various functions including emotions, self-awareness, and perception.

Integumentary: Relating to the integument, which refers to the skin and its associated appendages, such as hair, nails, and glands.

Integumentary System: The organ system consisting of the skin and its appendages, functioning to protect the body from external factors, regulate temperature, and provide sensory information.

Internal Respiration: The exchange of gases (oxygen and carbon dioxide) between the blood and the tissues of the body at the cellular level.

Interneurons: Neurons that serve as connectors or relays between sensory neurons and motor neurons, facilitating communication within the central nervous system.

Intestinal Trunk: A lymphatic vessel that receives lymph from the small intestines and delivers it to the cisterna chyli.

Intrapleural Pressure: The pressure within the pleural cavity, the space between the two layers of the pleura surrounding the lungs.

Intrapulmonary Pressure: The pressure inside the lungs during respiration, which fluctuates during inhalation and exhalation.

Inversion: A movement that involves turning the foot inward or toward the midline of the body.

Iodine: A chemical element necessary for the synthesis of thyroid hormones, also used in medical procedures as an antiseptic.

Ipsilateral: Referring to a structure or condition that occurs on the same side of the body.

Iris: The colored part of the eye that surrounds the pupil, controlling the amount of light entering the eye by adjusting the size of the pupil.

Iron: A mineral essential for the production of hemoglobin in red blood cells and for various metabolic processes in the body.

Irregular Bones: Bones that do not fit into the categories of long, short, or flat bones, often having complex shapes and serving unique functions.

Irregular Dense Connective Tissue: Connective tissue characterized by irregularly arranged collagen fibers, providing strength and support to various structures in the body.

Ischium: One of the three bones that make up the hip bone, forming the lower and posterior part of the pelvis.

Jejunum: The middle section of the small intestine, located between the duodenum and the ileum, where further digestion and absorption of nutrients occur.

Jugular Trunk: A major lymphatic vessel that receives lymph from the head, neck, and upper limbs, draining into the thoracic duct.

Keratinized Stratified Squamous Epithelium: A type of epithelial tissue found in the epidermis of the skin, characterized by multiple layers of cells that become progressively flatter and filled with keratin as they move toward the surface.

Kidney: A pair of bean-shaped organs located in the retroperitoneal space of the abdominal cavity, responsible for filtering waste products from the blood and regulating fluid and electrolyte balance.

Kidney Stones: Hard mineral and salt deposits that form in the kidneys, often causing pain and urinary problems when they obstruct the flow of urine.

Labia Majora: The outer, larger, and more prominent folds of skin located on either side of the vaginal opening in females.

Labia Minora: The inner, smaller, and thinner folds of skin located within the labia majora in females.

Lacrimal Bone: A small bone located in the medial wall of each orbit (eye socket), contributing to the formation of the tear ducts.

Lacunae: Small spaces or cavities within bone or cartilage that house cells, such as osteocytes (bone cells) or chondrocytes (cartilage cells).

Lamellae: Concentric layers of bone matrix surrounding the Haversian canals in compact bone tissue.

Lanugo Hair: Fine, unpigmented hair that covers the body of a developing fetus and is usually shed before birth.

Large Intestine: The final part of the digestive tract, consisting of the cecum, colon, rectum, and anus, responsible for absorbing water and electrolytes, forming and storing feces.

Large Veins: Veins that transport blood from various regions of the body back to the heart, often having larger lumens and thinner walls compared to arteries.

Laryngopharynx: The lower part of the pharynx, located behind the larynx (voice box) and extending to the opening of the esophagus and the entrance to the larynx.

Larynx: The organ of the respiratory system commonly referred to as the voice box, containing the vocal cords and playing a crucial role in sound production and air passage.

Lateral: Referring to a position or structure that is situated away from the midline of the body or further from a reference point.

Lateral Rotation: A movement that involves rotating a body part away from the midline or center of the body.

Leg: The lower limb of the body, extending from the knee to the ankle and consisting of the thigh (upper leg) and the calf (lower leg).

Lens: A transparent, biconvex structure located behind the iris of the eye, responsible for focusing light onto the retina to form clear images.

Leukocytes: White blood cells that play a crucial role in the immune system, defending the body against pathogens and foreign substances.

Limbic System: A group of interconnected brain structures involved in regulating emotions, behavior, and memory, including the hippocampus, amygdala, and cingulate gyrus.

Lipase: An enzyme produced by various glands, including the pancreas and salivary glands, involved in the breakdown of fats (lipids) during digestion.

Lipids: Organic compounds that are insoluble in water, including fats, oils, and waxes, serving as a source of energy, insulation, and structural components in cells.

Lips: The fleshy, movable parts forming the opening of the mouth, consisting of the upper and lower lips.

Liver: A large, reddish-brown organ located in the upper right abdomen, responsible for various metabolic functions, such as detoxification, synthesis of bile, storage of glycogen, and production of blood-clotting proteins.

Long Bones: Bones characterized by their elongated shape, consisting of a shaft (diaphysis) and two expanded ends (epiphyses), such as the femur, humerus, and tibia.

Loop Of Henle: A U-shaped segment of the nephron in the kidney, responsible for reabsorbing water and electrolytes from the filtrate.

Lumbar Region: One of the five regions of the vertebral column, located in the lower back, consisting of five lumbar vertebrae.

Lumbar Trunk: A lymphatic vessel that collects lymph from the lower limbs and abdominal wall, draining into the cisterna chyli.

Lumbar Vertebrae: The five vertebrae of the lumbar region of the vertebral column, situated in the lower back, supporting the weight of the upper body.

Lunate: One of the eight carpal bones of the wrist, situated between the scaphoid and triquetrum bones.

Lunula: The pale, crescent-shaped area located at the base of the fingernail or toenail, representing the visible part of the nail matrix.

Luteinizing Hormone: A hormone released by the anterior pituitary gland, stimulating ovulation in females and testosterone production in males.

Lymph Nodes: Small, bean-shaped organs of the lymphatic system that filter lymph and play a crucial role in immune defense, trapping and destroying pathogens and foreign substances.

Lymphatic Capillaries: Microscopic vessels that collect excess interstitial fluid, called lymph, and transport it toward the lymph nodes.

Lymphatic Collecting Vessels: Larger vessels that receive lymph from lymphatic capillaries and transport it toward the lymph nodes and eventually back to the cardiovascular system.

Lymphatic Ducts: The main vessels of the lymphatic system that return lymph to the bloodstream, including the thoracic duct and the right lymphatic duct.

Lymphatic System: A network of vessels, nodes, and organs involved in the transport of lymph and the immune response, helping to defend the body against infections and diseases.

Lymphatic Trunks: Large vessels formed by the convergence of multiple lymphatic collecting vessels, serving as major channels for lymph transport.

Lymphatic Vessels: Vessels that carry lymph throughout the body, including lymphatic capillaries, collecting vessels, trunks, and ducts.

Lymphocytes: A type of white blood cell responsible for immune responses, including the production of antibodies and the destruction of infected or abnormal cells.

Macromolecules: Large molecules made up of smaller subunits, such as carbohydrates, proteins, nucleic acids, and lipids.

Macrophages: Large phagocytic cells of the immune system that engulf and digest pathogens, cellular debris, and foreign substances.

Magnesium: A mineral essential for various biological processes, including muscle and nerve function, energy production, and bone health.

Major Calyx: The larger branches of the renal pelvis in the kidney that collect urine from the renal pyramids.

Major Histocompatibility Complex: A group of genes that encode proteins involved in the immune response, responsible for presenting antigens to immune cells and determining tissue compatibility in organ transplantation.

Major Minerals: Essential minerals required in relatively large amounts by the body, including calcium, phosphorus, potassium, sodium, chloride, and magnesium.

Male Reproductive System: The system of organs and structures involved in the production, storage, and transport of sperm, including the testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.

Malleus: One of the three small bones in the middle ear, commonly known as the hammer, that transmits sound vibrations from the eardrum to the inner ear.

Mammary Glands: Milk-producing glands in female mammals that develop during puberty and are responsible for lactation.

Mammary Region: The region of the body that encompasses the breasts or mammary glands.

Mandible: The lower jawbone, the largest and strongest bone of the face, involved in chewing, biting, and speaking.

Manganese: A trace mineral necessary for the proper functioning of enzymes involved in metabolism, bone development, and antioxidant defense.

Manus: The region of the hand, including the wrist, palm, fingers, and thumb.

Maxilla: The upper jawbone, forming part of the skull and contributing to the structure of the face.

Maxillary Sinuses: Paired sinuses located within the maxillary bones of the face, serving to lighten the skull and contribute to the resonance of the voice.

Mechanoreceptors: Sensory receptors that respond to mechanical stimuli such as pressure, touch, vibration, and stretch.

Medial: Referring to a position or structure that is situated closer to the midline of the body or closer to a reference point.

Medial Rotation: A movement that involves rotating a body part toward the midline or center of the body.

Mediastinum: The central region of the thoracic cavity between the lungs, containing the heart, great vessels, thymus, esophagus, trachea, and other structures.

Medium Veins: Veins that are larger than small veins but smaller than large veins, participating in venous return by carrying blood from the peripheral tissues toward the heart.

Medulla Oblongata: The lowermost part of the brainstem, involved in controlling vital functions, such as respiration, heart rate, blood pressure, and reflexes.

Meiosis: The process of cell division that produces haploid cells (gametes) for sexual reproduction.

Meissner's Corpuscles: Sensory receptors found in the skin, particularly in the fingertips and other areas sensitive to touch, responsible for detecting light touch and vibration.

Melanocyte-Stimulating Hormone: A hormone produced by the pituitary gland that regulates the production and distribution of melanin, the pigment responsible for skin, hair, and eye color.

Membranous Urethra: The portion of the male urethra that passes through the urogenital diaphragm and extends from the prostatic urethra to the external urethral orifice.

Memory B Cells: Specialized B cells that are generated during an immune response and "remember" specific pathogens, allowing for a quicker and more effective response upon subsequent exposure to the same pathogen.

Menopause: The natural cessation of menstruation and reproductive function in women, typically occurring in midlife.

Menstruation: The shedding of the uterine lining that occurs in women as part of the menstrual cycle, usually accompanied by bleeding.

Merkel Cells: Specialized cells found in the skin's epidermis that function as touch receptors and play a role in the sensation of light touch and shapes.

Merocrine: A mode of secretion in which secretory products are released from a cell by exocytosis without any loss of cellular material.

Mesentery: A fold of the peritoneum that attaches organs to the abdominal wall, providing support and containing blood vessels, nerves, and lymphatics.

Metabolism: The set of chemical reactions that occur in living organisms to sustain life and energy production.

Metacarpals: The bones of the hand between the carpal bones and the phalanges, forming the framework of the palm.

Metatarsals: The bones of the foot between the tarsal bones and the phalanges, supporting the weight of the body and providing balance and propulsion during walking and running.

Microglia: Small, specialized cells of the central nervous system that act as immune cells, providing defense against pathogens and participating in brain tissue repair.

Microvilli: Small, finger-like projections on the surface of certain cells, such as the epithelial cells lining the small intestine, involved in increasing surface area for absorption and secretion.

Micturition: The process of emptying the urinary bladder, commonly known as urination or voiding.

Midbrain: The middle part of the brainstem, involved in sensory and motor functions, including the relay of visual and auditory information and coordination of certain reflexes.

Midsagittal Plane: A vertical plane that divides the body or any body part into equal left and right halves, passing through the midline.

Minerals: Inorganic substances required by the body for various physiological functions, including the formation of bones and teeth, regulation of fluid balance, and enzymatic activity.

Minor Calyx: The smaller branches of the renal pelvis in the kidney that collect urine from the renal pyramids and transport it to the major calyces.

Minor Minerals: Essential minerals required in smaller amounts by the body, such as iron, zinc, copper, selenium, and iodine.

Mitosis: The process of cell division that produces two identical daughter cells.

Molybdenum: A trace mineral necessary for the functioning of certain enzymes involved in metabolism and nitrogen metabolism.

Monocytes: A type of white blood cell that plays a role in the immune response, including phagocytosis of pathogens and antigen presentation.

Mons Pubis: The rounded, fatty area located over the pubic symphysis in females.

Morula: An early stage of embryonic development consisting of a solid ball of cells formed by repeated cell divisions of the fertilized egg.

Motor Neurons: Neurons that transmit signals from the central nervous system to muscles, glands, or other effector organs, controlling their activity and enabling movement and physiological responses.

Mouth: The oral cavity, the entrance to the digestive system, where food is ingested and initial digestion takes place.

Mucosa-Associated Lymphoid Tissue: Lymphoid tissue found in various mucous membranes throughout the body, such as the respiratory, gastrointestinal, and urogenital tracts, playing a role in immune defense.

Muscle: A soft tissue composed of contractile cells or fibers that can generate force and produce movement.

Muscular Arteries: Arteries that have a thick tunica media with a high proportion of smooth muscle, allowing for vasoconstriction and regulating blood flow.

Muscular System: The system of muscles in the body, including skeletal muscles, smooth muscles, and cardiac muscle, responsible for movement, posture, heat production, and other functions.

Myosin: A protein found in muscle fibers that interacts with actin to generate muscle contractions.

Nail Bed: The tissue beneath the nail plate where the nail is formed and grows.

Nail Plate: The hard, keratinized structure that forms the visible part of the nail.

Nails: Hard, protective structures made of keratin that cover the tips of fingers and toes.

Naïve B Cells: B cells that have not yet encountered their specific antigen and are capable of initiating an immune response upon activation.

Nasal Bone: The small, rectangular bones that form the bridge of the nose.

Nasal Cavity: The hollow space behind the nose and within the skull, lined with mucous membranes and containing the nasal passages.

Nasal Concha (Nasal Turbinates): Bony structures within the nasal cavity that increase its surface area and help filter, humidify, and warm the inhaled air.

Nasopharynx: The upper part of the pharynx located behind the nasal cavity, serving as a passageway for air and containing the openings of the auditory tubes.

Navicular: A small bone located in the wrist (carpus) or foot (tarsus) with various functions depending on its location.

Negative Feedback: A regulatory mechanism in which the response to a stimulus counteracts or reverses the initial change, helping maintain homeostasis and stability in the body.

Nephron: The functional unit of the kidney responsible for filtering blood and producing urine, consisting of a renal corpuscle and renal tubules.

Nerve Endings: The terminal branches of neurons that detect and transmit sensory information, allowing for the perception of various sensations such as touch, temperature, pain, and pressure.

Nervous: Relating to the nervous system, which includes the brain, spinal cord, and nerves, and is responsible for coordinating and controlling bodily functions and responses.

Nervous System: The complex network of nerves, cells, and tissues that enables communication and coordination between different parts of the body, allowing for sensory perception, motor control, and higher cognitive functions.

Neural Stimulus: A signal or input that activates neurons and triggers a response in the nervous system.

Neuroglia: Also known as glial cells, non-neuronal cells of the nervous system that provide support, protection, and nourishment to neurons.

Neuron: A specialized cell responsible for transmitting electrical signals in the nervous system.

Neutrophils: The most common type of white blood cell involved in the immune response, particularly in the defense against bacterial infections, through phagocytosis and release of antimicrobial substances.

Nociceptors: Sensory receptors specialized in detecting and transmitting signals related to pain and tissue damage.

Nocturia: The need to wake up during the night to urinate.

Nondisplaced Fractures: Fractures in which the bone retains its normal alignment and position.

Non-Keratinized Stratified Squamous Epithelium: Epithelial tissue that lacks a layer of keratin and is found in areas of the body not subjected to high mechanical stress, such as the oral cavity, esophagus, and vagina.

Norepinephrine: A neurotransmitter and hormone released by the sympathetic nervous system, playing a role in the stress response, regulation of blood pressure, and various physiological processes.

Nose: The external organ of the face involved in the sense of smell and the intake of air into the respiratory system.

Nuclease: An enzyme that breaks down nucleic acids into their constituent nucleotides.

Nucleic Acids: Biological macromolecules, including DNA and RNA, that carry genetic information and play essential roles in protein synthesis and cellular function.

Oblique Fractures: Bone fractures that occur at an angle, diagonal to the long axis of the bone.

Oblique Plane: A plane or section that is oriented at an angle between the horizontal and vertical planes, cutting through a structure or body in a slanted manner.

Occipital Bone: The bone located at the back of the skull that forms the posterior part of the cranial vault and protects the brain.

Occipital Lobe: The region of the cerebral cortex located at the back of the brain, responsible for processing visual information and contributing to visual perception and interpretation.

Oculomotor Nerve: The cranial nerve responsible for controlling the movements of the eye and certain muscles involved in eyelid control.

Olfactory: Relating to the sense of smell.

Olfactory Nerve: The cranial nerve responsible for transmitting sensory information related to smell from the olfactory receptors in the nasal cavity to the brain.

Oligodendrocytes: Specialized glial cells in the central nervous system that produce and maintain the myelin sheath, an insulating layer around axons, enabling efficient electrical signal transmission.

Oocyte: A female gamete or egg cell, produced within the ovary, which can be fertilized by sperm to initiate pregnancy.

Open Fractures: Fractures in which the broken bone penetrates through the skin or mucous membranes, creating an open wound and increasing the risk of infection.

Optic Nerve: The cranial nerve responsible for transmitting visual information from the retina of the eye to the brain for visual processing and perception.

Organ Systems: Collections of organs and tissues that work together to perform specific functions and contribute to the overall functioning of the body, such as the cardiovascular system, respiratory system, digestive system, etc.

Oropharynx: The middle portion of the pharynx located between the oral cavity and the laryngopharynx, involved in the passage of air and food, as well as sound production.

Ossicles: The three small bones in the middle ear (malleus, incus, and stapes) that transmit sound vibrations from the eardrum to the inner ear.

Osteoblasts: Cells involved in bone formation, responsible for the synthesis and secretion of the bone matrix.

Osteoclasts: Cells involved in bone resorption and remodeling, responsible for breaking down and removing old or damaged bone tissue.

Osteocytes: Mature bone cells that are embedded in the bone matrix and play a role in maintaining bone structure and function.

Osteon: Also known as a Haversian system, the basic structural unit of compact bone, consisting of concentric layers of bone matrix surrounding a central canal containing blood vessels and nerves.

Osteoprogenitor: Cells found in bone tissue that have the ability to differentiate into osteoblasts, contributing to bone growth and repair.

Otolith: A small, calcified structure in the inner ear involved in detecting changes in head position and linear acceleration, contributing to the sense of balance and spatial orientation.

Ovaries: The female reproductive organs responsible for producing oocytes (eggs) and hormones, such as estrogen and progesterone.

Oviducts: Also known as fallopian tubes, the tubes connecting the ovaries to the uterus, providing a passageway for the transport of oocytes and the site of fertilization.

Ovulation: The release of a mature egg (oocyte) from the ovary, ready for fertilization by sperm.

Oxytocin: A hormone released by the posterior pituitary gland that plays a role in various physiological processes, including uterine contractions during childbirth and milk ejection during breastfeeding. It is also involved in social bonding and attachment.

P Wave: A component of an electrocardiogram (ECG) that represents atrial depolarization, the electrical activity associated with the contraction of the atria in the heart.

Pacinian Corpuscles: Sensory receptors located in the skin and other tissues that are sensitive to pressure and vibration.

Palatine Bone: A bone located in the skull that forms part of the hard palate, the floor of the nasal cavity, and a portion of the orbit.

Pancreas: An organ located in the abdomen that plays a crucial role in digestion and blood sugar regulation. It produces enzymes for the breakdown of food and hormones, such as insulin and glucagon, which regulate blood glucose levels.

Papillary Layer: The upper layer of the dermis, composed of connective tissue containing blood vessels, nerve endings, and papillae that contribute to the formation of fingerprints.

Parasagittal Plane: A vertical plane that divides the body into unequal right and left portions, running parallel to the midline.

Parasympathetic Nervous System: The division of the autonomic nervous system that promotes rest, relaxation, and the conservation of energy. It is responsible for activities such as digestion, lowering heart rate, and promoting glandular secretion.

Parathyroid Hormone: A hormone secreted by the parathyroid glands that regulates calcium and phosphate levels in the blood. It increases blood calcium levels by stimulating bone resorption and enhancing calcium reabsorption in the kidneys.

Paraurethral Gland: Also known as Skene's glands, they are small glands located near the urethral opening in females. They secrete a fluid that may contribute to female ejaculation.

Parietal Bone: One of the bones that form the sides and roof of the skull.

Parietal Layer: A serous membrane layer that lines the inner surface of the body cavity, such as the pleural cavities or pericardial cavity.

Parietal Lobe: The region of the cerebral cortex located at the top and sides of the brain, responsible for processing sensory information, spatial awareness, and perception of touch, pressure, and pain.

Parietal Pleura: The serous membrane that covers the walls of the pleural cavity and lines the thoracic cavity.

Parotid Gland: One of the major salivary glands located near the ear, responsible for producing saliva and secreting it into the oral cavity.

Pedal: Relating to the foot or feet.

Pelvic Cavity: The space within the pelvis that contains the urinary bladder, reproductive organs, and part of the digestive system.

Penial Shaft: The elongated, cylindrical portion of the penis.

Penis: The male reproductive organ involved in sexual intercourse and the passage of urine.

Pepsin: An enzyme produced in the stomach that plays a vital role in the digestion of proteins by breaking them down into smaller peptide fragments.

Pericardium: The double-layered sac that surrounds and protects the heart. It consists of the fibrous pericardium (outer layer) and the serous pericardium (inner layer).

Peripheral Nervous System: The division of the nervous system that consists of nerves and ganglia outside the brain and spinal cord. It is responsible for transmitting sensory and motor information between the central nervous system and the rest of the body.

Peritubular Capillary Bed: A network of small blood vessels that surround the renal tubules in the kidneys. They play a role in the reabsorption and secretion of substances during urine formation.

Phalanges: The bones of the fingers and toes.

Pharynx: The muscular tube that connects the nasal and oral cavities to the larynx and esophagus. It serves as a passage for air, food, and drink.

Phosphorus: An essential mineral that plays a critical role in various physiological processes, such as bone formation, energy metabolism, and DNA synthesis.

Photoreceptors: Specialized cells in the retina of the eye that detect and respond to light, allowing for vision. The two types of photoreceptors are rods (responsible for black and white vision in low light) and cones (responsible for color vision and visual acuity in brighter light).

Pinna: The visible part of the outer ear, also known as the auricle, which collects and directs sound waves into the ear canal.

Pisiform: A small bone located in the wrist, situated near the base of the palm.

Pituitary Gland: A small gland located at the base of the brain, often referred to as the "master gland." It secretes various hormones that regulate growth, development, metabolism, and other important functions.

Pivot: A type of joint that allows rotational movement around a central axis. It is characterized by a rounded bone articulating with a ring-like structure.

Planar: Relating to a flat or two-dimensional surface or structure.

Planes: Imaginary flat surfaces used as reference points for anatomical descriptions and medical imaging. Examples include the sagittal, frontal, and transverse planes.

Plantarflexion: The movement of pointing the foot downward, as in standing on tiptoes.

Plasma Cell: A type of white blood cell that produces and secretes antibodies, a key component of the immune response.

Platelets: Small, colorless cell fragments in the blood that play a crucial role in blood clotting and wound healing.

Pleura: A serous membrane that lines the thoracic cavity and covers the lungs, allowing for smooth movement during respiration.

Pleural Cavities: The potential spaces between the visceral and parietal pleurae that contain a thin layer of fluid, reducing friction during breathing.

Pleural Cavity: Either of the two cavities (left and right) located between the visceral and parietal pleurae, which house the lungs.

Pons: A region of the brainstem located above the medulla oblongata and below the midbrain. It plays a role in various functions, including relaying signals between different brain regions and coordinating certain motor activities.

Positive Feedback: A physiological mechanism in which the response to a stimulus amplifies or reinforces the initial change. It deviates from homeostasis and is involved in processes such as blood clotting and childbirth.

Posterior: Referring to the back or rear of a structure or body.

Potassium: An essential mineral and electrolyte involved in various physiological processes, such as nerve function, muscle contraction, and maintaining fluid balance.

Preload: In the context of cardiac physiology, it refers to the degree of stretch on the heart muscle fibers just before contraction. It is influenced by the volume of blood returning to the heart.

Prepuce: The fold of skin that covers the glans penis in males or the clitoral glans in females. It is commonly known as the foreskin in males.

Primary Bronchi: The two main branches of the trachea that enter the lungs, supplying air to the respective lungs' lobes.

Primary Hair: The first and fine hair that develops on a fetus, usually shed and replaced by vellus hair.

Primary Teeth: The first set of teeth that erupt in humans, also known as baby teeth or deciduous teeth.

Prolactin: A hormone secreted by the anterior pituitary gland that stimulates milk production in the mammary glands of females after childbirth.

Pronation: The inward rotation of the forearm, causing the palm to face backward or downward.

Proper Dense Connective Tissue: A type of connective tissue characterized by densely packed collagen fibers, providing strength and support to structures like tendons and ligaments.

Proper Loose Connective Tissue: A type of connective tissue with a loose arrangement of cells and fibers, filling spaces between organs and providing support while allowing for flexibility and movement.

Proprioceptive System: The sensory system responsible for providing information about body position, movement, and coordination, allowing for spatial awareness and control of body parts without visual input.

Prostate Gland: A walnut-sized gland located below the bladder in males, surrounding the urethra. It produces seminal fluid that nourishes and transports sperm.

Prostatic Urethra: The portion of the urethra that passes through the prostate gland.

Proteins: Large biomolecules composed of amino acids, essential for the structure, function, and regulation of cells and tissues. They play roles in enzymes, hormones, antibodies, structural components, and more.

Proximal: Referring to a location or position that is closer to the center of the body or the point of attachment.

Proximal Convoluted Tubule: The first segment of the renal tubule in the kidney nephron, responsible for reabsorbing water, ions, and nutrients from the filtrate back into the bloodstream.

Proximal Nail Fold: The fold of skin that surrounds the proximal end of the nail plate, protecting the nail matrix.

Pseudostratified Columnar Epithelium: A type of epithelial tissue composed of cells that appear stratified due to their varying heights but are all in contact with the basement membrane. It is commonly found in the respiratory tract, where it has cilia and goblet cells.

Puberty: The stage of development during which sexual maturation occurs, characterized by physical changes, the onset of reproductive function, and the ability to conceive offspring.

Pubis: One of the bones that make up the pelvis, located in the lower front portion.

Pulmonary Arteries: Blood vessels that carry deoxygenated blood from the heart's right ventricle to the lungs for oxygenation.

Pulmonary Circuit: The pathway of blood circulation between the heart and the lungs, where blood picks up oxygen and releases carbon dioxide.

Pulmonary Semilunar: A valve located between the right ventricle and the pulmonary artery, preventing the backflow of blood into the ventricle when the heart relaxes.

Pulmonary Trunk: The large artery that arises from the right ventricle of the heart and branches into the pulmonary arteries, carrying deoxygenated blood to the lungs.

Pulmonary Veins: Blood vessels that carry oxygenated blood from the lungs to the left atrium of the heart.

Pupil: The adjustable opening in the center of the iris of the eye, regulating the amount of light that enters the eye.

Purkinje Fibers: Specialized cardiac muscle fibers that transmit electrical signals through the ventricles of the heart, coordinating their contraction and contributing to efficient pumping of blood.

QRS Complex: The QRS complex is a waveform on an electrocardiogram (ECG) that represents the depolarization of the ventricles of the heart. It consists of the Q, R, and S waves.

Radius: One of the two long bones in the forearm, located on the lateral side (thumb side). It runs parallel to the ulna and contributes to the structure of the wrist joint and forearm.

Rectum: The terminal portion of the large intestine, responsible for storing feces until defecation.

Regular Dense Connective Tissue: A type of connective tissue characterized by densely packed collagen fibers arranged in a regular pattern, providing strength and support to structures like tendons and ligaments.

Renal Columns: Extensions of the renal cortex that project into the renal medulla, dividing it into triangular sections called renal pyramids.

Renal Cortex: The outer region of the kidney, containing nephrons responsible for filtration, reabsorption, and secretion.

Renal Pelvis: The expanded upper part of the ureter within the kidney, where urine collects before being transported to the urinary bladder.

Renal Pyramid: A triangular-shaped structure in the renal medulla of the kidney, consisting of nephrons and collecting ducts.

Repolarizes: The process of restoring the resting membrane potential of a cell following depolarization. In cardiac physiology, it refers to the repolarization of cardiac muscle cells, preparing them for another contraction.

Reproductive System: The collection of organs and tissues involved in reproduction, including the gonads (testes in males and ovaries in females), accessory reproductive structures, and the gametes (sperm in males and ova or eggs in females).

Residual Volume: The volume of air that remains in the lungs after maximum expiration, ensuring the lungs are never completely empty and maintaining gas exchange.

Respiration: The process of obtaining energy from the breakdown of glucose and other molecules, usually with the use of oxygen.

Respiratory Bronchioles: The smallest branches of the bronchial tree within the lungs, responsible for conducting air to the alveolar ducts and participating in gas exchange.

Respiratory System: The anatomical structures and physiological processes involved in respiration, encompassing the airways, lungs, and respiratory muscles.

Rete Testis: A network of tubules located within the testis, involved in the transport and modification of sperm.

Reticular Layer: The deeper layer of the dermis, composed of dense irregular connective tissue that provides strength and support to the skin.

Reticular Tissue: A type of connective tissue characterized by a network of reticular fibers, forming the framework of various organs and supporting blood vessels, lymph nodes, and other structures.

Retina: The innermost layer of the eye that contains the photoreceptor cells (rods and cones) and other neurons involved in the initial processing of visual information.

Rh System: A blood group system that determines the presence or absence of the Rh antigen on red blood cells. It is important for blood transfusion compatibility and can be a factor in pregnancy complications.

Right Lymphatic Duct: A lymphatic vessel that drains lymph from the right upper limb, right side of the head, and right side of the thorax, returning it to the venous circulation.

RNA: Ribonucleic acid, a molecule involved in protein synthesis and other cellular processes.

Root of the Penis: The base or attachment point of the penis, which connects to the pelvic bones.

Rotation: The movement of a body part around its axis, either medially (internal rotation) or laterally (external rotation).

Ruffini Endings: Sensory receptors located in the skin that detect stretch and continuous pressure, contributing to the perception of touch and joint position.

Sacrum: The sacrum is a triangular bone located at the base of the spine, formed by the fusion of five vertebrae. It connects the spine to the hip bones and provides support and stability to the pelvis.

Saddle: A type of synovial joint characterized by the articular surfaces of the bones resembling the shape of a saddle. This joint allows movement in multiple directions and is found in the thumb (carpometacarpal joint of the thumb).

Salivary Glands: Glands in the oral cavity that produce and secrete saliva, which aids in digestion and lubrication of food. The major salivary glands include the parotid, submandibular, and sublingual glands.

Sarcomere: The basic contractile unit of skeletal muscle. It is the segment of a myofibril between two Z discs and is responsible for muscle contraction by the sliding filament mechanism.

Sarcoplasmic Reticulum: A specialized type of endoplasmic reticulum found in muscle cells (myocytes) that stores and releases calcium ions necessary for muscle contraction.

Satellite Cells: Cells associated with muscle tissue that play a role in muscle growth, repair, and regeneration. They are involved in the repair of damaged muscle fibers and contribute to muscle hypertrophy.

Scaphoid: One of the carpal bones located near the base of the thumb. It is the largest bone in the proximal row of carpal bones and is important for wrist stability and movement.

Scapula: Also known as the shoulder blade, the scapula is a flat triangular bone located on the upper back. It forms part of the shoulder girdle and provides attachment points for various muscles involved in shoulder movement.

Scapular Region: The area of the back that overlies the scapula. It extends from the upper back to the shoulders and is an important region for muscle attachment and movement of the shoulder joint.

Schwann Cells: Specialized cells in the peripheral nervous system that wrap around and insulate nerve fibers with a myelin sheath. Schwann cells promote the efficient transmission of nerve impulses.

Sclera: The tough, fibrous, white outer layer of the eye that maintains the shape and protects the delicate inner structures. It is commonly referred to as the "white of the eye."

Scrotum: The external pouch of skin and connective tissue that houses the testes in males. It helps regulate the temperature of the testes, crucial for sperm production and fertility.

Sebaceous: Relating to sebaceous glands, which are small glands in the skin that secrete sebum, an oily substance that lubricates and waterproofs the skin and hair.

Secondary Bronchi: The branches of the bronchial tree that arise from the primary bronchi and supply each lobe of the lungs. They further divide into tertiary bronchi.

Secondary Hair: Hair that appears after the lanugo hair (fine hair covering a fetus) is shed. It is thicker and more pigmented, providing insulation and protection to the skin.

Secondary Teeth: Also known as permanent teeth, they are the second set of teeth that replace the primary (deciduous) teeth. These teeth typically begin to erupt around the age of 6 and are meant to last a lifetime.

Selenium: An essential trace mineral that acts as a cofactor for certain enzymes involved in antioxidant defense, thyroid hormone metabolism, and DNA synthesis.

Semicircular Canals: Three fluid-filled structures in the inner ear that are part of the vestibular system and contribute to the sense of balance and spatial orientation.

Seminal Vesicles: Glandular structures located near the base of the urinary bladder in males. They secrete a fluid that combines with sperm to form semen, providing nourishment and aiding in sperm motility.

Seminiferous Tubules: Highly coiled tubules within the testes where sperm production (spermatogenesis) occurs. These tubules are the site of sperm cell development and maturation.

Sensory Neurons: Neurons that transmit sensory information from sensory receptors to the central nervous system (brain and spinal cord). They play a vital role in detecting and relaying sensory stimuli such as touch, temperature, and pain.

Serotonin: A neurotransmitter primarily associated with regulating mood, appetite, and sleep. It also plays a role in various physiological functions, including gastrointestinal motility and platelet aggregation.

Serous Pericardium: The thin, double-layered membrane that surrounds the heart and consists of two layers: the parietal layer (lining the inner surface of the pericardial sac) and the visceral layer (also known as the epicardium, which covers the outer surface of the heart).

Sesamoid Bones: Small, round bones that develop within tendons, most commonly found near joints. They act as pulleys, reducing friction and increasing the efficiency of muscle contractions.

Sexual Hair: Hair that develops during puberty in the pubic and axillary regions, as well as in other areas influenced by androgens (male sex hormones) or estrogens (female sex hormones).

Short Bones: Bones that are approximately equal in length, width, and thickness, giving them a cube-like or boxy shape. Examples of short bones include the carpals in the wrist and the tarsals in the foot.

Sigmoid Colon: The S-shaped segment of the large intestine located between the descending colon and the rectum. Its primary function is to store and propel fecal material before elimination.

Simple Columnar Epithelium: A type of epithelial tissue characterized by its column-like shape, with nuclei typically located near the base of the cells. Simple columnar epithelium lines the digestive tract and often has specialized features, such as microvilli or goblet cells.

Simple Cuboidal Epithelium: A type of epithelial tissue composed of a single layer of cube-shaped cells. Simple cuboidal epithelium is found in various organs, including the kidney tubules and glands, where it functions in secretion and absorption.

Simple Squamous Epithelium: A single layer of thin, flattened cells that form a delicate epithelial barrier. Simple squamous epithelium lines the walls of blood vessels (endothelium) and air sacs of the lungs (alveoli), facilitating diffusion and filtration.

Stratum Basale: The deepest layer of the epidermis, consisting of a single layer of rapidly dividing cells. It is responsible for the continual renewal of the epidermis and contains melanocytes, which produce the pigment melanin.

Stratum Corneum: The outermost layer of the epidermis composed of multiple layers of flattened, keratinized cells called corneocytes. It acts as a protective barrier against environmental factors and water loss.

Stratum Granulosum: A layer of the epidermis located between the stratum spinosum and stratum corneum. It contains granules that contribute to the waterproofing function of the skin.

Stratum Lucidum: A translucent layer of the epidermis found only in thick skin, such as the palms of the hands and soles of the feet. It consists of flattened, densely packed cells that lack nuclei.

Stratum Spinosum: A layer of the epidermis situated above the stratum basale. It is characterized by spiny or prickly-shaped cells and is involved in the synthesis of keratin, a protein that provides strength to the skin.

Subclavian Trunk: A major artery that arises from the aortic arch and supplies blood to the upper limbs, shoulders, and some structures in the thoracic region.

Subcutaneous: Referring to the layer of tissue located beneath the skin, composed of fat cells and connective tissue. It serves as insulation, energy storage, and padding for the body.

Sublingual Gland: One of the major salivary glands located beneath the tongue. It produces saliva that helps with lubrication and begins the process of digestion.

Submandibular Gland: One of the major salivary glands situated beneath the mandible (lower jaw). It secretes saliva that aids in swallowing and digestion.

Sudoriferous: Relating to sweat glands. Sudoriferous glands are distributed throughout the skin and produce sweat, which helps regulate body temperature.

Sulfur: An essential mineral present in various proteins, enzymes, and vitamins. It is involved in many physiological processes and is a component of certain amino acids.

Superficial: Referring to a structure or location that is near the surface or external aspect of the body.

Superior: A directional term indicating a position above or higher in relation to another structure. It is often used to describe the placement of one structure in comparison to another.

Supination: The rotational movement of the forearm and hand that brings the palm facing upward or anteriorly. It is the opposite of pronation.

Surfactant: A substance produced by specialized cells in the lungs called type II alveolar cells. It helps reduce surface tension within the alveoli, preventing their collapse and facilitating efficient gas exchange.

Sutures: Fibrous joints found in the skull where the cranial bones are joined together. They are immovable joints that provide stability and protect the underlying brain.

Sympathetic Nervous System: One of the two divisions of the autonomic nervous system, responsible for the body's fight-or-flight response. It activates in times of stress or danger, increasing heart rate, dilating pupils, and redirecting blood flow to vital organs.

Symphyses: A type of cartilaginous joint characterized by fibrocartilage between the articulating bones. Symphyses provide strength and shock absorption and are found in structures such as the intervertebral discs and the pubic symphysis.

Synarthrosis: A type of joint characterized by immovable or nearly immovable articulations. Synarthroses provide stability and protection to the underlying structures.

Synchondroses: A type of cartilaginous joint in which the bones are joined by hyaline cartilage. Synchondroses allow for slight movement during growth and development, such as in the epiphyseal plates of long bones.

Syndesmoses: A type of fibrous joint in which the bones are connected by a ligament or interosseous membrane. Syndesmoses provide some degree of movement and flexibility.

Synostosis: A type of joint formed by the fusion of two separate bones into a single bone. Synostoses occur during skeletal development and can be seen in structures like the fusion of the cranial sutures.

Synovial: Referring to a type of joint characterized by a synovial cavity, articular cartilage, synovial fluid, and a joint capsule. Synovial joints allow for a wide range of movements and are the most common type of joint in the body.

Systemic Circuit: The portion of the cardiovascular system that carries oxygenated blood from the heart to the body's tissues and returns deoxygenated blood back to the heart.

Systolic: Pertaining to the phase of the cardiac cycle when the heart contracts and pumps blood into the arteries.

Systolic Pressure: The highest pressure recorded in the arteries during cardiac systole, when the heart is contracting and pumping blood. It is the top number in a blood pressure reading.

T Cell Receptors: Proteins found on the surface of T lymphocytes (T cells) that recognize specific antigens and play a crucial role in the immune response.

T Helper: A subtype of T lymphocytes (T cells) that help coordinate and regulate the immune response by secreting cytokines and interacting with other immune cells.

T Lymphocytes: A type of white blood cell that plays a central role in cell-mediated immunity. T lymphocytes are involved in recognizing and attacking foreign antigens and infected cells.

T Wave: A waveform seen on an electrocardiogram (ECG) that represents the repolarization of the ventricles of the heart.

Talus: A bone located in the ankle joint, forming part of the foot. It articulates with the tibia and fibula to allow for movements such as dorsiflexion and plantarflexion.

Tarsal: Referring to the bones of the foot known as tarsals. The tarsal bones are responsible for forming the posterior half of the foot and providing stability during weight-bearing activities.

Tarsals: The seven bones that make up the proximal portion of the foot, including the talus, calcaneus, navicular, cuboid, and three cuneiform bones.

Taste: The perception of flavors through the gustatory system, which involves taste buds located on the tongue and other parts of the oral cavity.

Teeth: Hard structures embedded in the jaws that are used for biting, chewing, and grinding food. Humans typically have two sets of teeth: primary (baby) teeth and permanent teeth.

Temporal Bone: A paired bone located on the sides and base of the skull, forming part of the cranial vault. The temporal bone houses the structures of the middle and inner ear and has attachments for various muscles.

Temporal Lobe: One of the four lobes of the brain, located on the sides of the brain above the ears. The temporal lobe is involved in auditory processing, memory, language comprehension, and emotion.

Terminal Bronchioles: The smallest branches of the bronchial tree in the respiratory system. Terminal bronchioles mark the end of the conducting zone and lead to the respiratory zone of the lungs.

Terminal Hair: The longer, thicker, and more deeply pigmented hair that grows in areas such as the scalp, eyebrows, and eyelashes. It differs from vellus hair, which is shorter, finer, and lighter in color.

Tertiary Bronchi: The subdivisions of the bronchial tree that arise from the secondary bronchi. Tertiary bronchi further divide into bronchioles within each lung.

Testes: The male reproductive organs responsible for producing sperm and testosterone. The testes are located in the scrotum and play a crucial role in reproduction.

Thalamus: A structure located deep within the brain, serving as a relay station for sensory information. The thalamus plays a vital role in sensory perception, motor control, and consciousness.

Thermoreceptors: Sensory receptors that detect changes in temperature. Thermoreceptors are found throughout the body and play a role in regulating body temperature.

Thoracic Cage: The bony structure that surrounds and protects the organs of the thoracic cavity, including the heart and lungs. It is formed by the ribs, sternum, and thoracic vertebrae.

Thoracic Cavity: The cavity within the thoracic cage that contains the heart, lungs, and other thoracic organs.

Thoracic Lymphatic Duct: The main lymphatic vessel responsible for draining lymph from the lower body, left upper limb, and left side of the head, neck, and thorax. It empties into the left subclavian vein.

Thoracic Region: The upper part of the trunk between the neck and the abdomen. It contains the thoracic vertebrae, rib cage, and thoracic organs.

Thoracic Vertebrae: The twelve vertebrae located in the thoracic region of the spine, between the cervical and lumbar vertebrae. They articulate with the ribs and form part of the posterior thoracic cage.

Thrombocytes: Another term for platelets, which are small cell fragments involved in blood clotting. They help stop bleeding by forming clots at the site of vascular injury.

Thymus: A glandular organ located in the upper chest, behind the sternum. The thymus plays a critical role in the development and maturation of T lymphocytes (T cells) involved in the immune response.

Thymus Gland: The endocrine gland responsible for producing hormones that regulate the development and function of T lymphocytes (T cells) within the immune system.

Thyroid Gland: An endocrine gland located in the neck, just below the Adam's apple. The thyroid gland produces hormones that regulate metabolism, growth, and development.

Thyroid-Stimulating Hormone: A hormone produced by the pituitary gland that stimulates the thyroid gland to release thyroid hormones. It plays a key role in regulating thyroid function.

Thyroxine: The main hormone produced by the thyroid gland. Thyroxine, also known as T4, regulates metabolism and influences various physiological processes in the body.

Tibia: The larger of the two lower leg bones, commonly known as the shinbone. The tibia provides structural support and is involved in weight-bearing activities.

Tidal Volume: The volume of air inspired or expired during normal breathing at rest. It represents the amount of air exchanged with each breath.

Tongue: A muscular organ located in the oral cavity, involved in taste, chewing, swallowing, and speech production.

Tonsils: Clusters of lymphoid tissue located in the throat and nasal cavity. Tonsils play a role in immune defense by trapping and removing pathogens entering the body through the oral and nasal routes.

Total Lung Capacity: The maximum volume of air that can be contained in the lungs after a maximum inspiration. It is the sum of all lung volumes, including tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume.

Trace: A term used to describe an essential mineral or nutrient that is required by the body in very small amounts.

Trachea: The windpipe, a tube-like structure that connects the larynx to the bronchi, allowing air to pass into and out of the lungs.

Transitional Epithelium: A type of stratified epithelium that lines organs and structures that need to stretch and accommodate volume changes, such as the urinary bladder.

Transportation: The movement of substances, such as oxygen, nutrients, hormones, and waste products, within the body through the circulatory and lymphatic systems.

Transverse Colon: The portion of the large intestine that extends horizontally across the abdomen, connecting the ascending colon to the descending colon.

Transverse Fractures: Bone fractures that occur in a horizontal or transverse plane across the bone, often resulting from a direct blow or trauma.

Transverse Plane: An imaginary plane that divides the body or an organ into superior (upper) and inferior (lower) portions. It is also known as the horizontal plane.

Trapezium: One of the eight carpal bones of the wrist. The trapezium is located on the thumb side of the hand and forms part of the thumb's joint.

Trapezoid: One of the eight carpal bones of the wrist. The trapezoid is located next to the trapezium and helps form the wrist joint.

Tricuspid: Referring to the tricuspid valve, which is located between the right atrium and right ventricle of the heart. It has three cusps and regulates blood flow between these chambers.

Trigeminal Nerve: The fifth cranial nerve, responsible for sensory information from the face and controlling the muscles involved in chewing.

Triiodothyronine: One of the thyroid hormones produced by the thyroid gland. Triiodothyronine, also known as T3, plays a key role in regulating metabolism and energy production.

Triquetral: One of the eight carpal bones of the wrist. The triquetral is located on the pinky side of the hand and contributes to wrist movement and stability.

Trochlear Nerve: The fourth cranial nerve, responsible for innervating the superior oblique muscle of the eye and contributing to eye movement and coordination.

Trophoblast: The outer layer of cells that forms during early embryonic development. The trophoblast plays a crucial role in implantation and placenta formation.

Tropomyosin: A protein involved in muscle contraction. Tropomyosin regulates the interaction between actin and myosin filaments in muscle cells.

Troponin: A protein complex found in muscle cells, particularly in cardiac and skeletal muscle. Troponin plays a key role in regulating muscle contraction and is used as a diagnostic marker for heart muscle damage.

True Ribs: The first seven pairs of ribs that directly attach to the sternum through their own costal cartilage, contributing to the anterior thoracic cage.

True Vocal Folds: The vocal cords located within the larynx that vibrate to produce sound during speech and singing.

Trypsin: An enzyme produced by the pancreas and involved in the digestion of proteins in the small intestine. Trypsin breaks down proteins into smaller peptide chains.

Tunica Externa: The outermost layer of blood vessels, such as arteries and veins. The tunica externa provides support and protection to the vessel.

Tunica Intima: The innermost layer of blood vessels, such as arteries and veins. The tunica intima is composed of endothelial cells and provides a smooth surface for blood flow.

Tunica Media: The middle layer of blood vessels, such as arteries and veins. The tunica media is composed of smooth muscle cells and elastic fibers, allowing for vasoconstriction and vasodilation.

Tunics: The layers of tissue that make up the walls of blood vessels. The three tunics are the tunica intima, tunica media, and tunica externa.

Ulna: One of the two long bones in the forearm, located on the inner side (medial) of the arm. It articulates with the radius and plays a role in forearm rotation and support.

Umbilical Region: The central region of the abdomen, surrounding the umbilicus (belly button).

Umbilicus: Commonly known as the belly button or navel, it is the scar left behind after the detachment of the umbilical cord during infancy.

Ureters: The muscular tubes that transport urine from the kidneys to the urinary bladder.

Urethra: The tube that carries urine from the urinary bladder to the exterior of the body. In males, it also serves as a passage for semen during ejaculation.

Urgency: A sudden and compelling urge to urinate, often associated with bladder dysfunction or urinary tract conditions.

Urinary Bladder: A muscular organ located in the pelvic cavity that stores urine until it is released through urination.

Urinary System: The organ system responsible for the production, storage, and elimination of urine. It includes the kidneys, ureters, urinary bladder, and urethra.

Urination: The process of emptying the urinary bladder by voluntarily relaxing the urethral sphincters and allowing urine to flow out of the body.

Uterus: A hollow, muscular organ located in the female pelvic cavity where fetal development occurs during pregnancy.

Vagina: The muscular canal in the female reproductive system that extends from the cervix to the external genitalia. It serves as the birth canal and the site of sexual intercourse.

Vaginal Opening: The external opening of the vagina.

Vagus Nerve: The tenth cranial nerve, also known as the "wandering nerve." It innervates many organs in the thoracic and abdominal cavities and plays a role in the parasympathetic nervous system.

Vas Deferens: A duct that carries sperm from the epididymis to the ejaculatory duct in males.

Vasa Recta: Capillary networks that surround the nephron loops (loops of Henle) in the kidneys. They play a role in the exchange of substances during urine formation.

Veins: Blood vessels that carry deoxygenated blood back to the heart. Veins typically have thinner walls and valves to prevent backflow.

Vellus Hair: Fine, short, and lightly pigmented hair that covers most of the body, except for certain areas, such as the scalp and eyebrows.

Vena Cava: The two largest veins in the body, the superior vena cava and the inferior vena cava, that return deoxygenated blood from the body to the right atrium of the heart.

Ventilation: The process of breathing, which involves the movement of air into and out of the lungs.

Ventral Cavities: The body cavities located toward the front (anterior) of the body, including the thoracic cavity and abdominopelvic cavity.

Ventricles: Chambers of the heart responsible for pumping blood. The heart has four ventricles: two atria (left and right) and two ventricles (left and right).

Venules: Small blood vessels that receive blood from capillaries and transport it to veins.

Vertebral Cavity: The space within the vertebral column that houses and protects the spinal cord.

Vertebral Column: Also known as the spine or spinal column, it is a series of individual vertebrae that provide structural support and protection to the spinal cord.

Vestibular Bulbs: Structures located on either side of the vaginal opening in females. They engorge with blood during sexual arousal.

Vestibular Folds: Also known as the false vocal cords, they are located within the larynx above the true vocal cords and help protect the airway during swallowing.

Vestibular System: The sensory system responsible for detecting changes in head position and movement, maintaining balance, and coordinating eye movements.

Vestibule: The space or area at the entrance of a body structure or organ, such as the nasal vestibule or vaginal vestibule.

Vestibulocochlear Nerve: The eighth cranial nerve, responsible for transmitting sensory information related to hearing and balance from the inner ear to the brain.

Villi: Small finger-like projections found in the small intestine and other areas of the body. They increase the surface area for nutrient absorption.

Virtuous Humor: Also known as the vitreous body, it is a gel-like substance that fills the space between the lens and the retina in the eye.

Visceral Layer: The inner layer of a serous membrane that covers organs within body cavities.

Visceral Pleura: The serous membrane that covers the surface of the lungs.

Vital Capacity: The maximum amount of air a person can exhale forcefully after a maximum inhalation. It represents the total volume of air involved in normal breathing.

Vitamins: Essential organic compounds required in small amounts for normal physiological function. They play various roles in metabolism, growth, and overall health.

Vulva: The external female genitalia, including the mons pubis, labia majora, labia minora, clitoris, vaginal opening, and urethral opening.

Wormian Bones: Small irregular bones that can occur within the sutures of the skull. They are also known as sutural bones.

Zinc: A trace element that is essential for various physiological processes, including growth, development, immune function, and wound healing.

Zona Fasciculata: One of the three layers of the adrenal cortex, responsible for producing glucocorticoid hormones, such as cortisol.

Zona Glomerulosa: One of the three layers of the adrenal cortex, responsible for producing mineralocorticoid hormones, such as aldosterone.

Zona Pellucida: A glycoprotein-rich layer surrounding the oocyte (egg) and playing a role in fertilization.

Zona Reticularis: One of the three layers of the adrenal cortex, responsible for producing androgens, including dehydroepiandrosterone (DHEA) and androstenedione.

Zygomatic Bone: Also known as the cheekbone or malar bone, it is a facial bone that forms part of the lateral wall and floor of the orbit (eye socket).

Zygote: The initial cell formed by the fusion of sperm and egg during fertilization, marking the beginning of a new individual's development.

This manual references and supports the OpenStax Anatomy & Physiology 2e textbook, along with other sources from the public domain.

Betts, J. G., Desaix, P., Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J., Womble, M. D., & Young, K. A. (2017). Anatomy & Physiology. OpenStax College, Rice University. ISBN-13: 978-1-938168-13-0

Bruce Blaus,  Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436.

Campos-Rodríguez R, Godínez-Victoria M, Abarca-Rojano E, Pacheco-Yépez J, Reyna-Garfias H, Barbosa-Cabrera RE, Drago-Serrano ME (2013) Stress modulates intestinal secretory immunoglobulin A. Front. Integr. Neurosci. 7:86. doi: 10.3389/fnint.2013.00086 http://journal.frontiersin.org/article/10.3389/fnint.2013.00086/full

Häggström, M (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). doi:10.15347/wjm/2014.008. ISSN 2002-4436. Creative Commons CC0 1.0 Universal Public Domain Dedication.

Stevenson, Harvey (2022). “Kisspeptin-neuron control of LH pulsatility and ovulation”. Front Endocrinol (Lausanne). 2022; 13: 951938. doi: 10.3389/fendo.2022.951938