Gastric Motility Lecture 29 . In addition to the longitudinal and circular components of the muscularis externa , there is present an oblique layer overlying the submucosa. Receptive relaxation occurs only in the Fundus and the upper Corpus . Though some passive stretch may occur, receptive relaxation is, at least in part, due to a centrally mediated reflex, initiated by swallowing, and resulting in inhibition of tonic contraction in the stomach wall , and consequent increase in intragastric volume .
Receptive relaxation is a largely vagally mediated reflex.
Receptive relaxation is one of the deglutition reflexes . These result from a series of local reflexes integrated within the ENS, involving interaction of longitudinal and circular muscle, modulated by ANS and gut hormones. Mechanism Regulating Motility -Motor activity in the distal stomach and in the intestinal tract is dictated by electrical phenomena arising in the smooth muscle itself. In the distal stomach , smooth muscle cells show a RMP of about 60 mV, outside positive. The frequency, number, and amplitude of response potentials in an ERA burst, will determine the strength and duration of contractions.