D313 Lab 13 The Respiratory System
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Western Governors University
D313 Anatomy and Physiology II with Lab
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Lab 13: The Respiratory System
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Pre-Lab Questions
1. What are two main functions of the nasal cavity mucosa?
The mucosa within the nasal cavity plays a critical role in protecting the respiratory system. Primarily, it filters the air by capturing dust, allergens, and microorganisms, thus preventing harmful particles from entering the lower airways. Secondly, it humidifies and warms the incoming air, which helps prevent dryness and irritation of the respiratory tract. These combined actions maintain a stable internal environment conducive to efficient gas exchange within the alveoli.
2. Why does the trachea have cartilaginous rings?
The trachea is supported by C-shaped cartilaginous rings that provide both flexibility and strength. These rings maintain the airway’s openness by preventing collapse during inhalation and exhalation. Moreover, the open portion of each ring, positioned posteriorly near the esophagus, allows flexibility during swallowing—facilitating the passage of food without compressing the trachea.
3. What is the pathway of oxygen from the nares to body tissues?
The pathway of oxygen begins at the nares (nostrils), moves through the nasal cavity, and continues into the pharynx, larynx, and trachea. From there, oxygen passes into the bronchi, bronchioles, and finally the alveoli, where gas exchange occurs. Once oxygen enters the alveoli, it diffuses into the pulmonary capillaries, binds with hemoglobin in red blood cells, and is transported through the bloodstream to various body tissues for cellular respiration.
4. How is asthma characterized?
Asthma is a chronic inflammatory condition of the airways marked by bronchoconstriction, swelling, and mucus hypersecretion. This leads to symptoms like wheezing, coughing, and shortness of breath. The disease is typically managed through inhaled corticosteroids to reduce inflammation and bronchodilators to relieve acute symptoms. Environmental triggers such as allergens, cold air, and stress can exacerbate the condition.
Experiment 1: Microscopic Anatomy of the Respiratory System
Table 1: Observations of Respiratory Structures
| Structure | Description |
|---|---|
| Trachea | A flexible, U-shaped tube lined with pseudostratified ciliated columnar epithelium containing goblet cells that secrete mucus to trap foreign particles. |
| Lung | A spongy, elastic organ with a grayish appearance, responsible for facilitating gas exchange between air and blood. |
Post-Lab Questions
1. Label the arrows in the microscopic slide images
A: Goblet cells
B: Basement membrane
C: Connective tissue of lamina propria
D: Cilia
E: Bronchiole
F: Bronchi
G: Alveoli
H: Capillaries
2. What alveolar features facilitate gas exchange?
Alveoli are designed to optimize gas exchange through thin epithelial walls (Type I pneumocytes), an extensive capillary network, and a large surface area. Additionally, the moist environment within the alveoli promotes efficient diffusion of oxygen into the blood and carbon dioxide out of it. Type II cells secrete surfactant to reduce surface tension and prevent alveolar collapse.
3. Why is mucus present in the trachea?
Mucus serves as a protective barrier that traps dust, microbes, and other particulates, preventing them from reaching the lungs. It also maintains airway moisture and supports immune defenses by containing antibodies and antimicrobial proteins that neutralize pathogens.
4. What is the function of cilia in the trachea?
Cilia on the tracheal epithelial cells beat rhythmically upward to propel mucus and trapped debris toward the pharynx. This process, known as the mucociliary escalator, is essential for keeping the airways clean and reducing infection risk.
Experiment 2: Virtual Model of the Respiratory System
(Insert screenshot of the epiglottis — user to provide)
Post-Lab Questions
| Question | Answer |
|---|---|
| How does diaphragm contraction affect thoracic cavity pressure and lung volume? | When the diaphragm contracts, thoracic volume increases, decreasing internal pressure, thus drawing air into the lungs (inhalation). Upon relaxation, pressure rises and air is expelled (exhalation). |
| Where does deoxygenated blood become oxygenated? | Oxygenation occurs in the alveoli of the lungs where gas exchange takes place between alveolar air and capillary blood. |
| Is the trachea located superior or inferior to the diaphragm? | The trachea is positioned superior (above) to the diaphragm. |
| Which structure is more medial: the right lung or the tracheal bifurcation? | The tracheal bifurcation is more medial. |
| What is the most inferior organ of the respiratory system? | The diaphragm is the most inferior structure associated with respiration. |
Experiment 3: Understanding Lung Mechanics
Table 2: Lung Mechanics Observations
| Observation | Description |
|---|---|
| Squeezed Bottle (Step 3) | The internal balloon expands as air is drawn in, simulating the inhalation process. |
| Released Bottle (Step 4) | The balloon contracts as air exits, replicating exhalation. |
Post-Lab Questions
- What happens to the balloon and why?
The balloon inflates due to air pressure entering through the straw, representing lung expansion during inhalation. - What if the bottle’s seal leaks?
A leak prevents the creation of negative pressure, meaning the balloon will not inflate properly—simulating the loss of pressure seen in a pneumothorax. - What causes a collapsed lung?
A collapsed lung (pneumothorax) occurs when air escapes into the pleural cavity, eliminating the pressure difference that keeps the lungs expanded. - Is a collapsed lung functional? Why or why not?
No. Once collapsed, the lung cannot expand or facilitate gas exchange, leading to oxygen deprivation in body tissues.
Experiment 4: Spirometry Data Analysis
Patient Spirometry Data Summary
| Patient | FVC (L) | FEV1 (L) | FEV1/FVC (%) | Interpretation |
|---|---|---|---|---|
| A | 4.93 | 4.10 | 83.3 | Asthma well managed |
| B | 2.16 | 1.93 | 89.7 | Mild asthma symptoms |
| C | 2.74 | 2.08 | 76.1 | Reduced lung capacity, possible surgery candidate |
| D | 2.53 | 2.00 | 78.95 | Potential airway obstruction |
| E | 2.29 | 2.03 | 88.6 | Normal respiratory function |
Post-Lab Questions
- Is Patient A managing asthma effectively?
Yes. Patient A’s results show normal FEV1/FVC ratios, indicating good asthma control. - Is Patient B suffering from asthma?
Yes. The results suggest airway resistance consistent with mild asthma. - Should Patient C undergo lung surgery?
Yes. The data shows significantly impaired lung function, warranting surgical evaluation. - What is the likely cause of Patient D’s symptoms?
Likely airway obstruction from chronic respiratory conditions such as COPD or asthma. - Is Patient E asthmatic?
No. Spirometry data indicates normal respiratory performance. - What are some limitations of spirometry in diagnosing respiratory diseases?
Spirometry outcomes depend heavily on patient effort, technique, and environmental factors. It cannot always distinguish between different pulmonary disorders and may yield false positives or negatives. Imaging and additional tests are often needed for accurate diagnosis.
Experiment 5: Fetal Pig Dissection
Post-Lab Questions
- Describe the interior lining of the trachea.
The tracheal lining consists of ciliated pseudostratified epithelium with mucus-secreting goblet cells. The cilia move mucus upward toward the pharynx to clear debris. Beneath the epithelium lies a vascular submucosa that nourishes the tissue. - Are there many blood vessels between the lungs and heart? Why?
Yes. Numerous pulmonary arteries and veins connect the lungs and heart, ensuring rapid gas exchange—oxygenating blood and removing carbon dioxide efficiently. - What is the function of the diaphragm during breathing?
The diaphragm is the primary muscle of respiration. Its contraction enlarges the thoracic cavity, allowing air to enter (inhalation), while relaxation reduces cavity volume, pushing air out (exhalation).
References
American Thoracic Society. (2023). Spirometry. https://www.thoracic.org/patients/patient-resources/resources/spirometry.pdf
Marieb, E. N., & Hoehn, K. (2018). Human Anatomy & Physiology (11th ed.). Pearson.
National Heart, Lung, and Blood Institute. (2020). Asthma. https://www.nhlbi.nih.gov/health-topics/asthma
D313 Lab 13 The Respiratory System
Tortora, G. J., & Derrickson, B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.
D313 Lab 13: The Respiratory System.