TAILIEUCHUNG - Encyclopedia Of Animal Science - G

Từ điển khoa học động vật vần G | GI Tract Anatomical and Functional Comparisons Edwin T. Moran Jr. Auburn University Auburn Alabama . INTRODUCTION The gastrointestinal GI tract provides nutrients to support the body and all its activities. Essentially six functions exist with the effectiveness of each one being reliant on its predecessor. From beginning to end these are food seeking oral evaluation gastric preparation for digestion small intestinal recovery of nutrients large intestinal action on indigesta and waste evacuation. GASTROINTESTINAL SYSTEM DIFFERENCES Gastrointestinal systems differ largely with respect to the presence of a meaningful symbiotic microbial population and its location. Simple-stomached animals Figs. 1A and B do not have an extensive microbial population to greatly alter nutrient recovery whereas ruminants Fig. 1C and nonruminant herbivores Fig. 1D support symbiotic populations prior to and after formal digestion by the small intestine respectively. All GI systems accomplish the same sequence of events but are anatomically and functionally modified to accommodate predominating food and microbial populations. SENSORY EVALUATION Sensory evaluation predominates in the oral cavity once food is prehended. Evaluation by mammals represents a complex of texture taste and aroma that generally arises during mastication. 2 Teeth and a mobile tongue aid prehension by mammals followed by mastication in a warm mouth lubricated by blends of viscous and serous types of saliva that optimize sensory detection. Ruminants masticate extensively and make considerable demand on serous saliva particularly from the parotid gland. Fowl have an oral cavity that differs markedly from mammals. Their eyes provide acute depth perception to accurately retrieve particulates but food size is limited by the absence of teeth a rigid beak and fixed oral dimension. Beak manipulations using an inflexible tongue coat the oral mass with viscous saliva to lubricate swallowing. Fowl appear to depend on .

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