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The Digestive System - The Oral Cavity and Salivary Glands...

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The Digestive System Introduction The digestive system ingests , digests and absorbs nutrients extracted from food; it is also responsible for the elimination of indigestible waste products. The digestive system is composed of the gastrointestinal tract and several digestive accessory organs. The chemical digestive processes break down the macromolecules into their monomers . Polysaccharides are broken down into monosaccharides; proteins are broken down into amino acids; fats are broken down into monoglycerides and fatty acids; and nucleic acids are broken down into nucleotides. These monomers are then absorbed into the blood and used by the body for a variety of functions. Anatomy and Physiology of the Digestive System Histology The GI tract is a long, muscular tube running from the oral cavity to the anus. The standard histology of these structures includes, from the inside out: an internal mucosal layer, the submucosa, the muscularis, and the outermost serosal layer.
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Unformatted text preview: The Oral Cavity and Salivary Glands The oral cavity is the site of ingestion . In the oral cavity, food is masticated . The addition of salivary amylase begins the breakdown of starches . The tongue manipulates ingested food resulting in increased mechanical disruption. The tongue is also the primary organ of taste; papillae on the surface of the tongue contain taste buds that respond to tastants in the food. Saliva is released from several structures within the oral cavity. Numerous small intrinsic salivary glands release saliva at a constant rate to keep the oral cavity moist. Three larger extrinsic glands ( see Figure 1 ) secrete saliva when stimulated by the presence of food in the oral cavity. Saliva can also be secreted in response to the thought or smell of food. Saliva performs several important functions within the oral cavity. Figure 1...
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