Zoology-Respiratory Organs

NEET Zoology Respiratory Organs MCQ Question

Type: MCQ-fact-Hard-Class 11

What causes the increase in intra-pulmonary pressure during expiration?

A

Decrease in thoracic volume

B

Increase in diaphragm contraction

C

Expansion of alveolar sacs

D

Increase in atmospheric pressure

Correct Answer

Option A

Detailed Explanation

During expiration, relaxation of the diaphragm and inter-costal muscles leads to a decrease in thoracic volume, which subsequently reduces pulmonary volume. This reduction in volume causes an increase in intra-pulmonary pressure, forcing air out of the lungs.

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