Question

In forceful expiration, which of the following neurons gets fired?

• A. VRG
• B. DRG
• C. Pneumotaxic centre
• D. Chemoreceptors

Answer 1

The Correct Option is A

In forceful expiration, the neurons that get fired are located in the Ventral Respiratory Group (VRG).

The human respiratory system is regulated by the respiratory centers in the brainstem, which include the VRG, Dorsal Respiratory Group (DRG), and other brain regions such as the pneumotaxic center. Different components of the respiratory centers are involved in various modes of breathing:

• Ventral Respiratory Group (VRG): This group contains neurons that are primarily responsible for activating the muscles involved in forceful expiration. During forceful expiration, which is required during activities such as heavy exercise or coughing, the VRG neurons are stimulated to induce contraction of accessory muscles, leading to a more forceful expulsion of air from the lungs.
• Dorsal Respiratory Group (DRG): Generally involved in regulating normal, rhythmic breathing patterns, primarily during inspiration.
• Pneumotaxic Centre: Modulates the activity of the respiratory centers to adjust the rate and pattern of breathing.
• Chemoreceptors: Detect changes in blood pH, carbon dioxide, and oxygen levels, informing the respiratory centers to adjust breathing rate accordingly, but they do not control forceful expiration directly.

Among the options given, the VRG is directly responsible for controlling the motor neurons that lead to muscle contractions involved in forceful expiration.