Respiratory Lab

We will explore of the respiratory system. This lab will provide you with a unique opportunity to deepen your understanding of the intricate workings of the human pulmonary system. We will be dissecting the pulmonary system of a fetal pig and measuring our own lung volumes using a spirometer. By combining practical dissection techniques with physiological measurements, we aim to gain insight into the structure and function of the respiratory system.

The respiratory system plays a vital role in maintaining the body's oxygen supply and removing carbon dioxide, thus enabling the efficient exchange of gases between the body and the environment. It consists of various components, including the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs. The lungs, composed of millions of tiny air sacs called alveoli, are the primary organs responsible for gas exchange.

During the dissection portion of this lab, we will focus on the pulmonary system of a fetal pig. While pigs are not human, their respiratory systems share many similarities, making them valuable models for studying human anatomy. The dissection will provide a hands-on opportunity to observe and identify key respiratory structures, such as the trachea, bronchi, and lungs.

After the dissection, we will move on to the spirometry portion of the lab. A spirometer is a device used to measure lung volumes and capacities. By breathing into the spirometer, we can obtain data on parameters such as tidal volume, inspiratory reserve volume, expiratory reserve volume, and vital capacity. These measurements allow us to assess the health and function of the respiratory system.

Materials

·         Dissection kit (scalpel, scissors, forceps, and probe)

·         Dissection tray

·         PPE

·         Fetal pig specimen

·         Pipet

·         Spirometer

·         Spirometer mouthpiece

FETAL PIG DISSECTION - RESPIRATORY SYSTEM INVESTIGATION 

In the first part of our lab, we will be performing a dissection on a fetal pig to investigate and remove the respiratory system. This will provide you with a unique opportunity to observe the anatomical structures of the respiratory system up close and understand their functions.

PROCEDURE

1. Position the fetal pig: Place the pig in a ventral recumbent position (belly up) on the dissection tray.

2. Examine the oral cavity: Open the pig's mouth (cut the mastication muscles through the cheeks to the corners of the mouth) and observe the structures inside, such as the tongue, hard and soft palate, and the opening to the pharynx at the back of the mouth.

3. Locate the epiglottis: The epiglottis is a flap of cartilage that covers the glottis (the opening to the trachea) during swallowing to prevent food from entering the respiratory system. It can be found at the back of the throat, behind the tongue (pull the lower jaw away from the upper).

4. Expose the larynx: As you make the midline incision along the ventral side of the neck, carefully expose the larynx, also known as the voice box. The larynx is a cartilaginous structure located between the pharynx and the trachea.

5. Dissect the larynx: Carefully remove the larynx from the surrounding tissue using scissors or a scalpel. Make a longitudinal incision along the back side of the larynx to expose its internal structures. Observe the vocal cords, which are responsible for producing sound, and the arytenoid cartilages, which help control the tension and position of the vocal cords.

6. Identify the trachea and esophagus: The trachea is a rigid, tube-like structure with cartilaginous rings. It is located anterior (in front of) the esophagus, which is a softer, muscular tube.

7. Follow the trachea: Carefully separate the trachea from the surrounding tissue and follow it down into the thoracic cavity. The trachea will bifurcate (split) into two primary bronchi, which enter the lungs.

8. Expose the thoracic cavity: Make a midline incision through the skin and muscle of the thorax, starting from the base of the neck and extending to the diaphragm. Be cautious not to puncture the lungs or heart. Gently open the ribcage using scissors, exposing the thoracic cavity.

9. Identify the lungs: The lungs are spongy, lobed organs located on either side of the heart. Fetal pigs have four lobes in the right lung and three lobes in the left lung. Observe the bronchi entering the lungs and the branching bronchioles within the lung tissue.

10. Remove the lungs: Carefully cut the bronchi and blood vessels connecting the lungs to the heart and trachea. Gently lift the lungs out of the thoracic cavity and place them on the dissection tray for further examination.

11. Examine the diaphragm: The diaphragm is a muscular sheet that separates the thoracic and abdominal cavities. It plays a crucial role in respiration by contracting and relaxing to facilitate inhalation and exhalation. Observe its position and attachment to the ribcage and spine.

12. Dissect the lungs: Examine the internal structures of the lungs, by carefully scraping away the external tissues of one lobe exposing the bronchial tree internally. Observe the bronchioles, alveolar ducts, and alveoli, which are responsible for gas exchange.

a. After debriding an undissected lung from fluid and other particulate, try to inflate the lung with a pipet and make it float.

13. Compare the respiratory system to humans: Throughout the dissection, take note of the similarities and differences between the fetal pig's respiratory system and that of humans. For example, humans have three lobes in the right lung and two lobes in the left lung, whereas fetal pigs have four lobes in the right lung and three lobes in the left lung.

14. Clean up: Once you have completed the dissection and examination of the respiratory system, properly dispose of the specimen according to your institution's guidelines. Clean and sterilize your dissection tools, tray, and work area. Remove your protective gear and wash your hands thoroughly.

In the space below diagram the passage of air form the nose to the alveoli.

Spirometry - Personal Lung Volumes and Total Lung Capacity

In the second part of our lab, we will be performing spirometry to collect data on your personal lung volumes. This non-invasive test will help you understand the different lung volumes and capacities, as well as how they relate to your respiratory health.

Procedure

1.       Prepare the spirometer: Ensure that the spirometer is clean and calibrated according to the manufacturer's instructions. Attach a disposable mouthpiece to the spirometer to maintain hygiene.

2.       Position the participant: Have the participant sit upright in a chair with their feet flat on the ground. This position allows for optimal lung function during the test.

3.       Measure lung capacities: Explain the procedure to the participant, emphasizing the importance of breathing normally during the tidal breaths and then taking a deep breath in and forcefully exhaling during the hard inhalation and exhalation.

a.   Ask the participant to place the mouthpiece in their mouth and breathe normally. Instruct them to inhale and exhale three times (normal quite breathing), ensuring they maintain a tight seal around the mouthpiece. Record the tidal volume for each breath.

b.   After the third tidal breath, instruct the participant to take a deep breath in, filling their lungs completely. Then, have them forcefully exhale as much air as possible into the spirometer. Record the inspiratory reserve volume (IRV) and expiratory reserve volume (ERV).

4.       Calculate the total lung capacity (TLC): To estimate the total lung capacity, you'll need to add the tidal volume (TV), IRV, ERV, and residual volume (RV). The residual volume is the amount of air remaining in the lungs after a forceful exhalation and cannot be measured directly with a spirometer. You can estimate the RV at 1500 ml.

a.   Vital Lung Capacity (VC) = TV + IRV + ERV

b.   Total Lung Capacity = VC + RV

5.       Analyze the results: Compare the participant's total lung capacity to reference values for their age, sex, and height to determine if their lung function is within the normal range.

6.       Clean up: After completing the test, properly dispose of the disposable mouthpiece and clean the spirometer according to the manufacturer's guidelines.

7.       Record your results and share the data with the class.  Complete the table.

Review Questions

1.       What is the function of the respiratory system in humans?
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

2.       How do the structures of the respiratory system enable the process of breathing?
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3.       How does smoking affect the respiratory system?
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

4.       What is the difference between the upper and lower respiratory tracts?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

5.       How can individuals protect their respiratory health?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

6.       What are the potential consequences of untreated asthma?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

7.       What is the difference between inhaling and exhaling?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

8.       How do the respiratory and cardiovascular systems work together?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

9.       How does the respiratory system respond to changes in altitude?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

10.    How can respiratory disorders such as chronic obstructive pulmonary disease (COPD) be managed?
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________