Which of the following factors primarily determines lung compliance?

• A. Number of alveoli
• B. Rate of breathing
• C. Elasticity of lung tissue
• D. Partial pressure of oxygen

Answer: (C)

Verified step by step guidance

1. Understand the concept of lung compliance: Lung compliance refers to the ability of the lungs to stretch and expand during breathing. It is influenced by the physical properties of the lung tissue and surrounding structures.
2. Identify the primary factor affecting lung compliance: Elasticity of lung tissue is the key determinant of lung compliance. Elastic fibers in the lung tissue allow the lungs to recoil after stretching, which is essential for normal breathing.
3. Eliminate incorrect options: The number of alveoli does not directly affect lung compliance, as compliance is more about the stretchability of the lung tissue rather than the quantity of alveoli. Similarly, the rate of breathing is a functional aspect of respiration, not a structural determinant of compliance. Partial pressure of oxygen relates to gas exchange, not the mechanical property of lung compliance.
4. Relate elasticity to lung compliance: Reduced elasticity (e.g., in conditions like emphysema) leads to increased compliance, making the lungs overly stretchy but less effective at recoiling. Conversely, increased elasticity (e.g., in fibrosis) decreases compliance, making the lungs stiffer and harder to expand.
5. Summarize the importance of elasticity: Elasticity of lung tissue is the primary factor that determines lung compliance because it governs the ability of the lungs to stretch during inhalation and recoil during exhalation, ensuring efficient ventilation.