PHSI 208 Lecture Notes - Lecture 50: Pylorus, Antrum, Chyme
Document Summary
Primary function: move nutrients, water and electrolytes from the external environment into the body"s internal environment. Central to regulation and integration of metabolic processes throughout the body. 10% of health care costs related to gi system. Extend from mouth large intestine (~15 ft length in live person) Gi tract: a long tube w/ muscular walls lined by transporting and secretory epithelial. Digestion = mechanical and chemical breakdown of food primarily occurs in the gut. Joined by secretions from accessory glandular organs: salivary glands, liver, gallbladder, pancreas. *technically, the gi tract is continuation of external environment (bacteria) Digestion begins in the mouth w/ mastication and the addition of saliva. Three pairs of salivary glands w/ multiple functions: moisten and lubricate food, amylase partially digests polysaccharides, dissolve some food molecules (taste, lysozyme kills bacteria. Esophagus = passageway from mouth to stomach (no digestion occurs here) Wall: top 1/3 is skeletal muscle, bottom 2/3 smooth muscle.
