Question

When ventilation and perfusion in lung tissue are ""matched,"" __________.

a) the rate of blood flow to the alveoli is equal to the rate of air flow to the alveoli
b) the partial pressures of oxygen and carbon dioxide in the capillaries leaving the alveoli are the same as the partial pressures of these gases in alveolar air
c) airways leading to the lung and capillaries perfusing the lung tissue are normal (unobstructed)
d) Answers a and c are correct.
e) All of the above are correct.

Answer 1

The correct answer is (b), indicating that when ventilation and perfusion are matched, the partial pressures of oxygen and carbon dioxide in the capillaries and alveoli are the same, ensuring efficient gas exchange.

Step-by-step explanation:

When ventilation and perfusion in lung tissue are matched, the best answer is (b) the partial pressures of oxygen and carbon dioxide in the capillaries leaving the alveoli are the same as the partial pressures of these gases in alveolar air. This condition ensures efficient gas exchange as oxygen diffuses into the blood and carbon dioxide is expelled from the blood into the alveolar air, driven by the difference in partial pressures.

The rates of airflow and blood flow being equal, and the airways and blood vessels being unobstructed, are important to maintaining matched ventilation and perfusion. However, these factors alone do not guarantee that the partial pressures will be equal, which is necessary for efficient gas exchange.