Physiology 3120 Lecture Notes - Enteric Nervous System, Gastrin, Pylorus
Document Summary
Occurs after food has entered the stomach and sits there. Least important phase; contributes very little to the increase in acid secretion that results from ingestion of a meal. Other important components of gastric exocrine secretion: pepsin. Secreted from oxyntic glandular mucosa, but not from the oxyntic cell; secreted by chief cell, which secretes an inactive precursor called pepsinogen. Secretes inactive form because you don"t want pepsin breaking down the mucosal. Within the lumen, pepsinogen activated to pepsin by cleavage; acid catalyzes this proteins itself (i. e. auto-digestion) conversion. Chief cell under cholinergic control: ach released due to food anticipation or presence, ach thus stimulates the secretion of both hcl (from oxyntic cells) and pepsinogen (from chief cells) Within mucosa, there are chemoreceptors that detects h+ concentrations and release ach to activate the chief cells. Just a washout product of the oxyntic cell (i. e. anytime oxyntic cell secretes, if secreted as well)