Question

The amount of air that moves in or out of the lungs with each respiratory cycle is:

• A. Inspiratory reserve volume
• B. Expiratory reserve volume
• C. Tidal volume
• D. Residual volume

Hint:

Tidal volume (TV) is the air exchanged during each normal breath, approximately 500 mL in an average adult.

Answer 1

The Correct Option is C

Step 1: Understanding lung volumes. Lung volumes are physiological measurements that describe different aspects of respiration: 
- Tidal volume (TV): The amount of air that moves in and out of the lungs with each normal breath (~500 mL in an average adult). 
- Inspiratory reserve volume (IRV): The additional air that can be inhaled after a normal inspiration. 
- Expiratory reserve volume (ERV): The additional air that can be exhaled after a normal expiration. 
- Residual volume (RV): The air remaining in the lungs after maximum expiration. 

Step 2: Why tidal volume is the correct answer. Since the question asks for the air exchanged during each normal respiratory cycle, this directly corresponds to the tidal volume (TV), which represents the regular breathing volume. 

Step 3: Why other options are incorrect. 
- (A) Inspiratory reserve volume: Represents extra air inhaled beyond normal breathing, not the standard breath volume. 
- (B) Expiratory reserve volume: Represents extra air exhaled beyond normal breathing, not the standard breath volume. 
- (D) Residual volume: Represents air remaining in the lungs after full expiration, not the air exchanged in a normal breath.