Nervous Control of Breathing - Physiology of Quiet Breathing

Nervous Control of Breathing

Physiology of Quiet Breathing

• Quiet Inspiration

  • Begins when Ventral Respiratory Group (VRG) initiates inspiratory signals.
  • These signals are transmitted through nerve pathways, specifically affecting:
  • External intercostal muscles
  • Diaphragm

• Mechanism of Action

  • The inspiratory signals maximize contraction of the external intercostal muscles and the diaphragm, leading to an increase in thoracic volume.

• Quiet Expiration

  • Occurs passively when the Ventral Respiratory Group (VRG) is inhibited.
  • Resulting in a cessation of inspiratory signals, allowing for the relaxation of respiratory muscles and a decrease in thoracic cavity volume that enables air to be expelled from the lungs.

• Significance of Signals

  • Thus, quiet inspiration and expiration are a result of a regulatory cycle where the VRG alternately activates during inhalation and inhibits during exhalation, leading to rhythmic breathing patterns.