Pneumotaxic center:It is situated in upper Pons.It is formed by nucleus parabrachialis.Function: it controls medullary respiratory centers, particularly the inspiratory center through apneustic center. Expiratory center:It is situated in medulla oblongata anterior and lateral to the inspiratory centerIt is also called ventral group of respiratory neuronsIt is formed by neurons of nucleus ambiguous and nucleus retro ambiguous Function: this center is inactive during quiet breathing and inspiratory center is the active center, but during forced breathing or when the inspiratory center is inhibited it becomes active. Inspiratory center:Inspiratory center is situated in upper part of medulla oblongataThis center is also called dorsal group of respiratory neuronsIt is formed by nucleus of tractus solitariusFunction: it is concerned with inspiration. There are two centers in each group:Medullary Centers:Inspiratory centerExpiratory center Pontine Centers:Pneumotaxic centerApneustic center
Respiration is regulated by two mechanisms:Nervous or neural mechanismChemical mechanismNervous Mechanism: It involves respiratory centers, afferent and efferent nerves.Respiratory centers: The centres in the medulla oblongata and pons that collects sensory information about the level of oxygen and carbon dioxide in the blood and determines the signals to be sent to the respiratory muscles.Stimulation of these respiratory muscles provide respiratory movements which leads to alveolar ventilation.Respiratory centers are situated in the reticular formation of the brainstem and depending upon the situation in brainstem, the respiratory centers are classified into two groups:Medullary centersPontine centers