GUT PHYSIOLOGY Secretion 2 Dr Jack Grider Rm

GUT PHYSIOLOGY Secretion 2 Dr. Jack Grider Rm 12 -004 Sanger Hall 828 -1853 jgrider@vcu. edu 2009

Secretion: Gastroduodenal Junction

Secretions at the Gastroduodenal Junction PANCREATIC: -Serous component: Water and bicarbonate ion -Protein component: pancreatic enzymes BILIARY -Serous component: Water and bicarbonate -Protein & other: bile and related secretions INTESTINAL: -Serous: Water and electrolyte

Secretion: Pancreas Endocrine portion insulin, somatostain, glucagon, pancreatic polypeptide Exocrine portion water, electrolyte, enzymes

Secretion: Exocrine Pancreas

Secretion: Exocrine Pancreas: serous

Secretion: Exocrine Pancreas: Protein • Storage in membrane bound zymogen granules • Storage as pro-enzymes • Trypsin inhibitor • Acidification of granule • Initial activation by enterokinase

Secretion: Exocrine Pancreas Enterocyte Gut Lumen Pancreas

Secretion: Exocrine Pancreas • Proteases (75%) – endo & exo – trypsin • Amylase • Lipases – Phospholipase cholesterol ester hydrolyase • Other enzymes – nucleases, elastases, etc • Other proteins – procolipase, trypsin inhibitor

Secretion: Control Mechanisms Neural Hormonal major multiple hormones Interactions

Secretion-Exocrine Pancreas: Neural Control

Secretion: Hormonal control Secretin: water and Bicarbonate ion CCK: enzyme component -multiple stimulants of CCK -interactions with neural control PP & PYY: inhibitory control.

Secretion: Exocrine Pancreas Regulation by secretin

Secretion: Exocrine Pancreas Regulation by CCK 6

Secretion: Exocrine Pancreas Regulation by CCK 7

Secretion: Exocrine Pancreas PP & PYY

Secretion: Exocrine Pancreas

Secretion: Exocrine Pancreas

Secretion: Intestinal Goblet cells: cells mucus Duodenal Glands: water & bicarbonate ion Enterocyte -villus migration (6 days) -secretory cells in crytps -water and chloride ion -cystic fibrosis transmembrane regulator (CFTR channel) and Cl. C 2 channel CFTR Channel CFTR Nutrient Absorption Nutrient (Carriers) Basolateral Sodium Basolateral Pump carriers Na pump

Secretion: Intestinal Cl. C 2 Cholera Tx

Secretion: Intestinal Enteric neurons from the submucosal plexus project all the way to the tip of the villus and innervate mucosal cells. Both sensory and motor neurons innervate the villus and crypt cells

Secretion: Intestinal Enteric neurons from myenteric and submucosal plexus, and extrinsic neurons from the sympathetic and parasympathetic nervous system regulate secretomotor neurons (VIP & Ach) and secretory reflexes. SSt, Opioid and SNS inputs are inhibitory; cholinergic are excitatory.

Secretion