Question

Inspiration occurs when the ________ is less than the ________.

A)tidal volume; vital capacity
B)intrapulmonary pressure; atmospheric pressure
C)intrapleural pressure; transpulmonary pressure
D)thoracic cavity volume; lung volume

Answer 1

Inspiration takes place when the intrapulmonary pressure decreases below atmospheric pressure, allowing air to flow into the lungs.

Step-by-step explanation:

Inspiration occurs when the intrapulmonary pressure is less than the atmospheric pressure. During inspiration, the diaphragm and intercostal muscles contract, increasing the volume of the thoracic cavity. As volume increases, air pressure inside decreases, leading to a pressure gradient that causes air to flow into the lungs until pressures equalize.

Therefore, the correct answer to the student's question is B) intrapulmonary pressure; atmospheric pressure. The intrapleural pressure is typically lower than the intrapulmonary pressure, but it is not the direct cause for inspiration. It plays a role by helping to create a negative pressure that facilitates lung expansion.