PSIO 532 Study Guide - Final Guide: Chyme, Protein Kinase, Amylase
Graduate Physiology – GI Tract
This image shows the stimulants for release of CCK from I cells and secretin release from S cells.
Of note, the I cells and S cells “taste” the specific stimulants in the lumen of the gut to
activate release of the hormones. The released CCK can mediate pancreatic secretion by either
activating vagal sensory afferents that results in stimulation of pancreatic acinar cell secretion
though a vago-vagal reflex involving the CNS or through the circulation (i.e. hormonal action).
Secretin also acts through neural (not shown) and hormonal pathways on the pancreas
stimulating secretion from both ductal cells and acinar cells.
Pancreatic acinar cell is the functional unit of the exocrine pancreas. It synthesizes, stores, and
secretes digestive enzymes.
CCK acts on the pancreas but it is MADE in the intestines (I cells - duodenum); partially digested
food components cause the release of CCK from the I-cells.
For S-cells: acid, FFA, releasing peptides cause the secretion of secretin (neutralizes the acid by
secreting bicarbonate fluid)
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Document Summary
This image shows the stimulants for release of cck from i cells and secretin release from s cells. Of note, the i cells and s cells taste the specific stimulants in the lumen of the gut to activate release of the hormones. The released cck can mediate pancreatic secretion by either activating vagal sensory afferents that results in stimulation of pancreatic acinar cell secretion though a vago-vagal reflex involving the cns or through the circulation (i. e. hormonal action). Secretin also acts through neural (not shown) and hormonal pathways on the pancreas stimulating secretion from both ductal cells and acinar cells. Pancreatic acinar cell is the functional unit of the exocrine pancreas. Cck acts on the pancreas but it is made in the intestines (i cells - duodenum); partially digested food components cause the release of cck from the i-cells. For s-cells: acid, ffa, releasing peptides cause the secretion of secretin (neutralizes the acid by secreting bicarbonate fluid)
