D313 Lab 13 The Respiratory System

Student Name

Western Governors University 

D313 Anatomy and Physiology II with Lab

Prof. Name

Date

Pre-Lab Questions

1. What are two main functions of the nasal cavity mucosa?

The mucosal lining of the nasal cavity performs essential protective and conditioning functions for the respiratory system. One primary function is filtration, whereby airborne contaminants such as dust particles, pollen, and microorganisms are trapped by mucus and nasal hairs before reaching the lower respiratory tract. This mechanism significantly reduces the risk of infection and irritation.

A second major function is air conditioning, which involves warming and humidifying inhaled air. By adjusting air temperature and moisture levels, the nasal mucosa protects delicate lung tissues from desiccation and thermal shock. Together, these functions help maintain optimal conditions for gas exchange within the lungs and support overall respiratory health.

2. Why does the trachea have cartilaginous rings?

The trachea is reinforced with C-shaped cartilaginous rings that provide both structural integrity and flexibility. These rings prevent the trachea from collapsing during breathing, ensuring a continuous and unobstructed airway for air movement into and out of the lungs.

The incomplete posterior portion of each cartilage ring faces the esophagus, allowing it to expand during swallowing. This anatomical adaptation permits food to pass smoothly into the digestive tract without compromising airflow, highlighting the coordinated relationship between the respiratory and digestive systems.

3. What is the pathway of oxygen from the nares to body tissues?

Oxygen enters the body through the nares (nostrils) and travels into the nasal cavity, where it is filtered, warmed, and humidified. From there, it passes sequentially through the pharynx, larynx, and trachea, eventually reaching the bronchi and progressively smaller bronchioles.

The pathway terminates at the alveoli, microscopic air sacs surrounded by capillaries. Here, oxygen diffuses across the thin alveolar membrane into the bloodstream, binds to hemoglobin in red blood cells, and is transported via systemic circulation to body tissues, where it supports cellular respiration and energy production.

4. How is asthma characterized?

Asthma is a chronic inflammatory respiratory disorder characterized by episodic airway narrowing due to bronchoconstriction, mucosal edema, and excessive mucus production. These changes result in symptoms such as wheezing, chest tightness, coughing, and difficulty breathing.

Asthma symptoms are often triggered by allergens, physical exertion, cold air, or emotional stress. Management typically involves long-term anti-inflammatory medications, such as inhaled corticosteroids, combined with short-acting bronchodilators to relieve acute symptoms and maintain airway patency.

Experiment 1: Microscopic Anatomy of the Respiratory System

Table 1

Observations of Respiratory Structures

Post-Lab Questions (Experiment 1)

1. Label the arrows in the microscopic slide images

• A: Goblet cells

• B: Basement membrane

• C: Connective tissue of the lamina propria

• D: Cilia

• E: Bronchiole

• F: Bronchi

• G: Alveoli

• H: Capillaries

2. What alveolar features facilitate gas exchange?

Alveoli are structurally optimized for gas exchange through several key features. Their walls are composed primarily of Type I pneumocytes, which form an extremely thin barrier to minimize diffusion distance. A dense capillary network surrounds each alveolus, maximizing contact between air and blood.

Additionally, the alveoli provide a vast surface area and maintain a moist internal environment to facilitate diffusion. Type II pneumocytes secrete pulmonary surfactant, which reduces surface tension and prevents alveolar collapse during exhalation.

3. Why is mucus present in the trachea?

Mucus in the trachea functions as a defensive barrier, trapping inhaled particles, pathogens, and pollutants before they can reach the lungs. It also maintains hydration of the airway lining and contains immune components, such as antibodies and antimicrobial substances, that help neutralize harmful microorganisms.

4. What is the function of cilia in the trachea?

Cilia are microscopic, hair-like projections on epithelial cells that beat in a coordinated upward motion. This movement propels mucus and trapped debris toward the pharynx, where it can be swallowed or expelled. This process, known as the mucociliary escalator, is critical for maintaining airway cleanliness and preventing respiratory infections.

Experiment 2: Virtual Model of the Respiratory System

(Insert screenshot of the epiglottis — provided by user)

Post-Lab Questions

Experiment 3: Understanding Lung Mechanics

Table 2

Lung Mechanics Observations

Post-Lab Questions

What happens to the balloon and why?
The balloon inflates as air pressure increases inside it, representing lung expansion during inhalation caused by negative thoracic pressure.

What if the bottle’s seal leaks?
A leak prevents the formation of negative pressure, so the balloon cannot inflate properly, mimicking conditions seen in a pneumothorax.

What causes a collapsed lung?
A collapsed lung occurs when air enters the pleural cavity, disrupting the pressure gradient required to keep the lung inflated.

Is a collapsed lung functional? Why or why not?
No. A collapsed lung cannot expand sufficiently to support gas exchange, leading to impaired oxygen delivery to tissues.

Experiment 4: Spirometry Data Analysis

Patient Spirometry Data Summary

Post-Lab Questions

Is Patient A managing asthma effectively?
Yes. Normal spirometry ratios indicate effective asthma control.

Is Patient B suffering from asthma?
Yes. Results suggest mild airflow limitation consistent with asthma.

Should Patient C undergo lung surgery?
Yes. Significantly reduced lung volumes warrant further surgical evaluation.

What is the likely cause of Patient D’s symptoms?
Airway obstruction possibly due to chronic respiratory disease.

Is Patient E asthmatic?
No. Spirometry values fall within normal limits.

What are some limitations of spirometry in diagnosing respiratory diseases?
Spirometry depends on patient effort and technique and cannot always differentiate among respiratory disorders. Additional diagnostic tools are often required.

Experiment 5: Fetal Pig Dissection

Post-Lab Questions

Describe the interior lining of the trachea.
The trachea is lined with ciliated pseudostratified epithelium containing goblet cells that secrete mucus. Beneath this lining lies a vascular submucosa that supports nourishment and immune defense.

Are there many blood vessels between the lungs and heart? Why?
Yes. Extensive pulmonary vasculature ensures efficient transport of oxygenated and deoxygenated blood, supporting rapid gas exchange.

What is the function of the diaphragm during breathing?
The diaphragm drives ventilation by altering thoracic volume. Its contraction enables inhalation, while relaxation facilitates exhalation.

References

American Thoracic Society. (2023). Spirometry.

Marieb, E. N., & Hoehn, K. (2018). Human anatomy & physiology (11th ed.). Pearson.

National Heart, Lung, and Blood Institute. (2020). Asthma.

Tortora, G. J., & Derrickson, B. H. (2017). Principles of anatomy and physiology (15th ed.). Wiley.

D313 Lab 13: The Respiratory System.