Questions: What happens to air pressure in the lungs during inhalation? The volume of the chest cavity increases, which decreases the air pressure in the lungs.

The answer is the first one: The volume of the chest cavity increases, which decreases the air pressure in the lungs.

Explanation for each option:

1. The volume of the chest cavity increases, which decreases the air pressure in the lungs.

   • This is correct. During inhalation, the diaphragm contracts and moves downward while the intercostal muscles contract to expand the rib cage. This increases the volume of the chest cavity, leading to a decrease in air pressure inside the lungs compared to the outside atmosphere, causing air to flow into the lungs.

2. The volume of the chest cavity stays the same during inhalation, which has no effect on the air pressure in the lungs.

   • This is incorrect. The volume of the chest cavity does not stay the same during inhalation; it increases, which affects the air pressure.

3. Inhalation has no effect on air pressure in the lungs.

   • This is incorrect. Inhalation directly affects air pressure in the lungs by decreasing it, allowing air to flow in.

4. The volume of the chest cavity decreases, which increases the air pressure in the lungs.

   • This is incorrect. The volume of the chest cavity actually increases during inhalation, not decreases.

5. The air pressure in the lungs remains the same during inhalation.

   • This is incorrect. The air pressure in the lungs decreases during inhalation, allowing air to enter the lungs.

In summary, during inhalation, the volume of the chest cavity increases, leading to a decrease in air pressure in the lungs, which facilitates the inflow of air.