Structure, Characteristics and Regulation of the Stomach Chapter 17 Pages

General Characterisics J-shaped “Pouch” Upper-left abdominal area Extra Layer of Muscle Mixing Rugae Regions: Cardia Fundus Body Pylorus Pyloric Sphincter Hypertrophic Pyloric Stenosis

Gastric Secretions Gastric Pits/Glands  Produce Gastric Juice Chyme – mixture of food & gastric juice Cells and What they Produce Mucous  Mucus Protection Ulcers Parietal  HCl Activates pepsinogen Chief  digestive enzymes Pepsin – most important; Proteins Produced as pepsinogen (inactive) Gastric Lipase – Fats Intrinsic Factor – absorption of B12

Regulation Controlled by nervous system & hormones Parasympathetic – increase activity Vagus Causes the release of Gastrin Hormones Gastrin – increases Gastric glands Somatostatin – decreases Parietal cells Cholecystokinin – decreases activity Small intestines Intestinal Somatostatin – decrease activity Phases Cephalic Before Gastric During Alkaline Tide Intestinal after

Mixing & Emptying Very Little Absorption H2O, Alcohol Rate of emptying depends on Food Type Carbs (quickest)  Proteins  Fats (slowest) Enterogastric Reflex Slows movement of chyme to small intestines Vomiting Reflex Quick and Backwards Nausea