Download Revision - Control of Food Intake and GI Hormones

CONTROL OF FOOD INTAKE AND GI HORMONES
15/05/08
PHYSIOLOGICAL FACTORS AFFECTING APPETITE
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Blood glucose levels are sensed by the hypothalamus; low glucose stimulates hunger
Fat ingestion stimulates release of CCK which slows gastric emptying and reduces hunger
Calcitonin released by the thyroid reduces hunger
Leptin released by adipocytes reduces hunger
Somatostatin stimulates hunger
Serotonin, dopamine and GABA all reduce hunger
GASTROINTESTINAL HORMONES
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Gastrin
o Released from G-cells in the stomach antrum and duodenum
o Acts on parietal and ECL cells in the stomach body
o Stimulates gastric acid secretion and histamine release (further promoting acid secretion)
o Release triggered by peptides and amino acids in the stomach
CCK
o Released from I-cells in the proximal small intestine
o Acts on acinar cells of the exocrine pancreas and the gall bladder
o Stimulates pancreatic and biliary secretions
o Release triggered by lipids, peptides and amino acids in the small intestine
Secretin
o Released from S-cells in the duodenum
o Acts on duct cells of the exocrine pancreas and parietal cells in the stomach body
o Inhibits gastrin / gastric acid secretion and stimulates fluid pancreatic secretions
o Release triggered by acid in the duodenum
Somatostatin
o Released from D-cells in the stomach and duodenum (and α-islet cells of the pancreas)
o Acts on parietal, G-cells and ECL cells in the stomach
o Inhibits gastrin / histamine / gastric acid secretion
o Release triggered by low pH in the stomach antrum
Peptide YY
o Released from endocrine cells in the ileum and colon
o Inhibits pancreatic secretions
o Release triggered by lipids in the ileum
VIP
o Released from neurones of the ENS
o Acts on acinar cells of the exocrine pancreas
o Stimulates pancreatic secretions