How signals are delivered p.291 IV. Integration & Control of G.I. Function How signals are delivered
Regulation of Gastric Activity p.619 of text Regulation of Gastric Activity
Phases of Gastric Secretion Cephalic Phase of Gastric Secretion (initiated by brain) Gastric Phase of Gastric Secretion (initiated by gastric events) vagus nerve vagus nerve FOOD HCl HCl Distension Peptides circulation circulation G G gastrin gastrin
HOW IT WORKS AT THE RECEPTOR LEVEL Combined neurocrine, endocrine and paracrine events in the activation of gastric HCl secretion Acetylcholine neural input neurocrine ACh receptor PARIETAL cell histamine receptor H/K P ECL cell transduction-activation events HCl secretion histamine-secreting cell H/K P gastrin receptor paracrine release of histamine Gastrin hormonal input endocrine ECL cell = enterochromaffin-like cell G cell = gastrin-secreting cell circulation G cell
Turning the G-cell On and Off p.292 Turning the G-cell On and Off vagus nerve ACh ACh Circulating cholinergic neuron GRP Gastrin gastric mucosa neuron - + ACh GRP D G (Somatostatin) (Gastrin) cell SS cell + + H+ digested protein Gastric Lumen Gastric Lumen
Turning the G-cell On and Off p.292 Turning the G-cell On and Off vagus nerve ACh ACh Circulating cholinergic neuron GRP Gastrin gastric mucosa neuron GRP + ACh D - G (Somatostatin) (Gastrin) cell SS cell + + H+ digested protein Gastric Lumen SS = somatostatin
Integration of Gastric Secretion p.623 of text Integration of Gastric Secretion
G.I. HORMONES p.293/94 Gastrin (17 AA) Cholecystokinin (CCK (33 AA)) Structure of Secretin (27 AA) (comparison with other GI hormones)
Intestinal Phase of Gastric Function D. Duodenal Integration & Control p.624 of text Intestinal Phase of Gastric Function D. Duodenal Integration & Control
Duodenal Response to Acidity Regulation by Secretin + - gall bladder liver HCl motility NaCl + H2O HCO3 NaHCO3 Secretin HCl + NaHCO3 NaCl + CO2 + H2O
- Duodenal Response to Food + Regulation by CCK (Cholecystokinin) CCK gall bladder Bile FOOD + - liver fats & peptides bile & enzymes fat & protein digestion HCl