For a Human to Inhale, the Rib Muscles and Diaphragm

Question

For a human to inhale, the rib muscles and diaphragm must
A)contract, decreasing pressure inside the lungs.
B)relax, increasing pressure inside the lungs.
C)contract, increasing pressure inside the lungs.
D)relax, decreasing pressure inside the lungs.

Accepted Answer

When the rib muscles and diaphragm contract, the volume inside the lungs increases, which leads to a decrease in pressure. This creates a pressure gradient that allows air to flow into the lungs, which is inhalation. Therefore, A is the correct choice as it describes the process of inhaling.