3. Decreasing pulmonary pressure –> Aneurysm of pulmonary vessels.
Show Answer
Correct Answer � A
Explanation
Ans. A.
1. Collapsed capillaries do not conduct blood.
2. Increased pulmonary pressure –> Fall in pulmonary vascular resistance
3. Greater pulmonary pressure –> distention of pulmonary vessels.
Detailed explanation:
1. Not all capillaries in the pulmonary circulation are normally open; collapsed capillaries do not conduct blood. 2. An increase in pulmonary artery pressure results in the recruitment of capillaries, in which collapsed vessels are opened when pulmonary artery pressure increases, resulting in a fall in pulmonary vascular resistance. 3. Higher pressure also results in the distention of pulmonary vessels, which also reduces resistance owing to the increased radius of the vessels.