Breathing - a sensorimotor act that integrates nervous influences arising from nearly every level of the brain and upper spinal cord.
Respiration functions:
Metabolism - maintaining tissue oxygenation and normal acid-base balance; regulated mainly by reflex neural mechanisms located in the posterior-dorsal region of the pons and in the medulla;
Behavioral control of breathing - integration with swallowing, and verbal and emotional communication.
Respiratory rhythm is an intrinsic property of the brainstem.
This rhythm is regulated in the intact brain via:
vagus nerve - conveys pulmonary stretch afferents to inhibit lung over inflation ;
glossopharyngeal nerve - from carotid sinus brings afferents that carry information about blood oxygen and carbon dioxide content; can ↑ respiratory rate and depth;
serotoninergic neurons in the ventral medulla may also serve as chemoreceptors;
The respiratory center is composed of several groups of neurons located bilaterally in the medulla oblongata and pons. It is divided into three major collections of neurons:
A dorsal respiratory group - located in the dorsal portion of the medulla; which mainly causes inspiration;
A ventral respiratory group - located in the ventrolateral part of the medulla; which mainly causes expiration;
The pneumotaxic center; located dorsally in the superior portion of the pons; which mainly controls rate and depth of breathing.