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Gas exchange at the respiratory membrane...

Gas exchange at the respiratory membrane is efficient because
I. the difference in partial pressure are substantial .
II. the gases are lipid-soluble.
III. blood flow is very rapid.
IV. the distance is minimized by having only one cell layer.
V. the total surface area is large .

A

II and III

B

I , IV ,and V

C

I, II and V

D

I , III, IV and V

Text Solution

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The correct Answer is:
To determine the efficiency of gas exchange at the respiratory membrane, we need to evaluate each of the given statements: 1. **Statement I: The difference in partial pressures are substantial.** - This statement is true. The efficiency of gas exchange is largely dependent on the difference in partial pressures of oxygen and carbon dioxide between the alveoli and the blood. A greater difference in partial pressure enhances the rate of diffusion, allowing for more effective gas exchange. 2. **Statement II: The gases are lipid-soluble.** - This statement is also true. Oxygen and carbon dioxide are both lipid-soluble gases, which allows them to easily diffuse across the lipid bilayer of the alveolar and capillary membranes. This property facilitates efficient gas exchange. 3. **Statement III: Blood flow is very rapid.** - This statement is somewhat misleading. While blood flow is important for maintaining a gradient for gas exchange, it is not the primary reason for the efficiency of gas exchange at the respiratory membrane. Therefore, this statement is not necessarily true in the context of the question. 4. **Statement IV: The distance is minimized by having only one cell layer.** - This statement is true. The respiratory membrane is extremely thin, consisting of only one cell layer from the alveolar epithelium and one from the capillary endothelium, which minimizes the distance that gases must diffuse. This thin barrier is crucial for efficient gas exchange. 5. **Statement V: The total surface area is large.** - This statement is true. The lungs have a large surface area due to the numerous alveoli present, which increases the area available for gas exchange. A larger surface area allows for more gas molecules to diffuse simultaneously, enhancing efficiency. **Conclusion:** Based on the evaluation: - Statements I, II, IV, and V are true. - Statement III is not a primary factor for efficiency. Thus, the total number of true statements is **4** (I, II, IV, and V). ### Summary of True Statements: - I: True - II: True - III: False - IV: True - V: True ### Final Answer: **4 statements are true.** ---
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