Comment on secretion in the small intestine.
Distension, chyme, vagal activity, and hormones stimulate the cells of crypts to secrete 1-2 litres of fluid per day.
- Distension: Leads to activation of mechanoreceptors
- Acidity of chyme: leads to activation of S-cells - these release the hormone secretin
- Breakdown products in chyme: Leads to activation of I-cells - These release the hormone cholecystokinin.
Intestinal fluid secretion helps neutralise chyme, this is aided by liver and pancreatic secretions