What is the normal expiratory reserve volume (ERV) for an adult?

• A. 500 mL
• B. 750 mL
• C. 1000 mL
• D. 1250 mL

Answer: (C)

Expiratory reserve volume (ERV) refers to the amount of air that can be forcibly exhaled after the expiration of a normal tidal volume. For a healthy adult, the normal value for this volume typically ranges between 1000 mL to 1200 mL. The option identifying a value of 1000 mL aligns well within this standard range, making it a representative estimate of what one would expect in an adult's pulmonary function.

Understanding the significance of ERV is important in the context of lung function. It reflects the ability of the lungs to expel air beyond the normal exhalation, which can be crucial in assessing overall respiratory health. Variations outside the normal range could indicate conditions affecting lung capacity or compliance, such as restrictive lung diseases, which could limit the ability to expel air fully.

Therefore, the value of 1000 mL accurately represents the normal expiratory reserve volume for an adult, providing insight into lung function and health.