Outline 12.doc

Outline 12 - GASTROINTESTINAL TRACT - STRUCTURE AND DISEASES I. Introduction Gastrointestinal tract (GIT): eight sections: mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus four accessory organs: salivary glands, liver, gall bladder, pancreas II. Structure: fig. 22.1 III. Special features of GIT A. Mucosal lining B. Mechanical processes mouth smooth muscle contraction ? peristalsis, churning of stomach; haustral contractions moistening in stomach, small intestine C. Chemical processes mouth - carbohydrates stomach- proteins small intestine - carbohydrates, proteins, and fats D. Absorption Small amount in mouth Most in small intestine. E. Immune system ? GALT ? lymph tissue ? tonsils, adenoids, other lymphatic tissue, Peyer?s Patches IV. GIT Flora A. Mouth ? hundreds of species of bacteria, Candida & a few protists; biofilm or microbes coat teeth Esophagus, stomach, and small intestine have sparse populations Large intestine ? many bacteria, fungus, protists; E. coli in colon helps in synthesis of Vit. K V. GIT Diseases A. Dental caries: surface of enamel ? treated with filling; deep into dentin and nerve pulp = toothache Streptococcus mutans and Streptococcus sobrinus ? acid causes enamel to degrade Nursing bottle caries ? in baby?s primary teeth B. Gastroenteritis ? general term for ?inflammation of the stomach and small and large intestines?; ?stomach flu? (misnomer) Etiology: viruses, bacteria, or protists; food or water contaminated with toxins from bacteria or other sources, or from medications. 1.Viral; 50-70% Most caliciviruses, i.e. Norwalk viruses; s & s: watery diarrhea and emesis, headache, fever, abdominal cramps; last 1-10 days, usually not serious, unless immuno-compromised or unable to take in enough fluids