What is the primary duty of the ventral respiratory group (VRG)?

The primary duty of the ventral respiratory group (VRG) is controlling expiration. The VRG is located in the medulla oblongata of the brainstem and plays a crucial role in the rhythmic nature of breathing. While it is involved in both inspiration and expiration, it is particularly important for the active phase of expiration. During exercise or situations that require increased ventilation, the VRG becomes especially active, facilitating the forceful expulsion of air by sending signals to respiratory muscles.

In contrast, the functions related to heart rate regulation and fluid balance are managed by other systems and body regions, specifically the autonomic nervous system and the renal system, respectively. The VRG does not play a direct role in those processes, which underscores why the focus is on its significance in respiratory function, particularly expiration.