Respiration is involuntarily regulated by a hierarchy of brainstem nuclei: pontine centers (the pneumotaxic center, comprising the parabrachial nucleus, and the apneustic center) modulate the timing of the respiratory cycle, while medullary centers (the dorsal respiratory group, centered on the nucleus tractus solitarius, and the ventral respiratory group) generate and execute the rhythm. Intrinsic rhythmogenesis arises from pacemaker neurons of the pre-Bötzinger complex, whose leaky cation channels produce spontaneous depolarization and set eupneic breathing at roughly 12–16 breaths per minute; efferent signals descend to somatic motor neurons in the ventral gray horn, exiting via the phrenic (C3–C5) and intercostal (T1–T11) nerves to drive the diaphragm and external intercostals. Afferent input from central chemoreceptors (sensing CSF pH as a proxy for arterial CO2) and peripheral chemoreceptors, stretch, proprioceptive, irritant, and juxtacapillary receptors modulates these centers, making this a core topic of neural control within respiratory and autonomic physiology.
Respiration is involuntarily regulated by a hierarchy of brainstem nuclei: pontine centers (the pneumotaxic center, comprising the parabrachial nucleus, and the apneustic center) modulate the timing …