The cephalic reflexes of digestion are those AUTONOMIC and ENDOCRINE rcflexes involved in the metabolism of food that are triggered by sensory contact with food rather than by postingestional mechanisms. They are such things as salivation and INSULIN secretion which prepare the body to receive, digest and absorb food. There are three defining traits: (1) the AFFERENT limb of the REFLEX originates in receptor mechanisms of the head and OROPHARYNX, (2) a relay in the CNS is involved, (3) the EFFERENT limb of the rcflex involves autonomic and endocrine processes controlling secretion, absorption and the motility of the gastrointestinal tract.
This is a process familiar to us all: for example, the sight and smell of food (1—the afferent limb) is information processed via the CNS (2—the CNS relay) that can trigger release of saliva from the salivary glands in the mouth (3—the efferent limb). It was proposed by Terry Powley that VENTROMEDIAL HYPOTHALAMIC SYNDROME was caused by an exaggeration of the cephalic reflexes of digestion.
