What volume serves to prevent collapse of the alveoli during exhalation?

The volume that serves to prevent the collapse of the alveoli during exhalation is known as residual volume. This volume reflects the amount of air that remains in the lungs after a maximal exhalation. It is crucial for maintaining the patency of the alveoli; without this residual air, the alveoli could collapse, leading to compromised gas exchange and various respiratory issues. Residual volume ensures that oxygen exchange can continue even between breaths.

While other options related concepts, they do not primarily serve the role of preventing alveolar collapse. Dead space refers to areas in the lungs where air does not participate in gas exchange, vital capacity is the total amount of air that can be forcefully exhaled after a maximum inhalation, and functional residual capacity encompasses both the residual volume and the expiratory reserve volume—yet it does not solely guarantee the prevention of alveoli collapse. Thus, the residual volume specifically highlights the protective function required to keep the alveoli open and functioning properly.