Certified Rehabilitation Registered Nurse (CRRN) Practice Exam

What is defined as the volume of air exhaled after the deepest possible inspiration?

1. Tidal volume

2. Vital capacity

3. Residual volume

4. Inspiratory reserve volume

The correct answer is: Vital capacity

The definition sought in the question pertains to the total volume of air that can be exhaled after taking the deepest possible breath in. This volume is known as vital capacity. Vital capacity is an important measurement in respiratory physiology as it reflects the maximum amount of air that can be controlled, influencing aspects of respiratory health and fitness. In contrast, tidal volume refers to the volume of air inhaled or exhaled in a normal breath during regular, relaxed breathing, making it significantly less than the amount involved in vital capacity. Residual volume, on the other hand, is the amount of air that remains in the lungs after a maximal exhalation, preventing lung collapse but not measured by the ability to exhale after a deep breath. Inspiratory reserve volume is the volume of air that can be inhaled after a normal inhalation, further differentiating it from the vital capacity measure, which encompasses both the air inhaled during deep inspiration and the volume exhaled. Thus, vital capacity accurately captures the essence of the question by encompassing the total air expelled after a full inhalation, distinguishing it firmly from the other pulmonary volumes.