Question

as exercise levels increase, which of the following physiological changes occurs in the respiratory system?
a. the respiratory muscles shrink.
b. the lungs expand in size.
c. the trachea widens.
d. the airways narrow.

please select the best answer from the choices provided.

○ a
○ b
○ c
○ d

Explanation:

To solve this, we analyze each option:

• Option A: Respiratory muscles (like diaphragm, intercostal muscles) strengthen with exercise, they don't shrink. So A is incorrect.
• Option B: During exercise, the demand for oxygen increases. The lungs expand more (due to increased respiratory rate and depth) to take in more air. This is a key physiological change.
• Option C: The trachea is a rigid structure and does not widen with exercise. So C is incorrect.
• Option D: Airways (like bronchi, bronchioles) actually dilate (widen) during exercise to allow more air flow, they don't narrow. So D is incorrect.

Answer:

B. The lungs expand in size.