Answer:
The correct answer is option B- pressure within the alveoli.
Explanation:
Intrapulmonary pressure is the pressure within the lungs especially in the alveoli of the lungs so is also known as "intra-alveolar pressure".
This pressure helps in the breathing process as :
1. During inspiration - The thoracic cavity volume increases due to which the intra-pulmonary pressure becomes less than the atmospheric pressure which causes the lungs to inhale about 500 ml of air.
2. During expiration- the thoracic volume decreases which cause the intra-pulmonary pressure larger than atmospheric pressure which causes the lungs to exhale the air.
Thus, option B- pressure within the alveoli is the correct answer.
