26.20 : 呼吸的神经控制

Groups of neurons in the brainstem called the respiratory centers mediate the regulation of respiration.

The two primary centers are the medullary respiratory center in the medulla oblongata and the pontine respiratory center in the pons.

The medullary respiratory center has two components: the dorsal respiratory group, or DRG, and the ventral respiratory group, or VRG.

During normal breathing, the DRG sends impulses via the phrenic and intercostal nerves to the diaphragm and external intercostal muscles, causing them to contract and induce inhalation.

After about two seconds, the DRG becomes inactive, allowing these muscles to relax, causing exhalation.

The VRG, through its pre-Bötzinger complex, generates the breathing rhythm by regulating the rate at which the DRG neurons fire action potentials.

The remaining VRG neurons regulate forceful breathing by controlling the accessory breathing muscles.

The pontine respiratory group transmits impulses to the VRG to fine-tune the breathing rhythms during vocalization, sleep, and exercise.