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 determine the correct answer, we analyze each option:

• Option A: Respiratory muscles (like diaphragm, intercostal muscles) strengthen and do not shrink with increased exercise. So A is incorrect.
• Option B: With regular exercise, lung capacity and the ability of lungs to expand (due to stronger respiratory muscles and improved lung function) can effectively increase in functional size (though structural size change is minimal, the functional expansion of lung volume during respiration increases). This is a valid physiological adaptation.
• Option C: The trachea is a rigid - like structure (supported by cartilage rings) and does not widen in response to exercise. So C is incorrect.
• Option D: During exercise, airways (bronchi, bronchioles) dilate (widen) to allow more air flow, they do not narrow. So D is incorrect.

Answer:

B. The lungs expand in size.