BIO26 CHAPTER 14 - Chapter 14 Digestive system. 1. The...

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Chapter 14 Digestive system. 1. The digestive system includes the mouth, pharynx, stomach, small intestine, and large intestine, as well as the accessory digestive organs, the teeth and salivary glands in the head and the liver, gallbladder, and pancreas in the abdominal cavity. a. Digestive/gastrointestinal tract – the esophagus, stomach, small intestine, and large intestine. b. Motility; the movement of food through the esophagus to the stomach. c. Secretion; digestive are exocrine secretions, because they enter the lumen of the GI tract. The stomach and intestine also secret several hormones that regulate digestive functions. d. Digestion; the breakdown of food molecules into their smaller subunits. Eg. Proteins into amino acids; starch and disaccarhcardies mono saccardies. Etc etc happens in the small intestine e. The absorption; transport of the subunit molecules from the lument of the small intestine into the blood or lumph. f. Excretion. Wastes that are not absorbed can be temporarily store in the large intestine until they’re excreted as feces. 2. Esophagus: transport food to the stomach from the pharynx a. Swallowed food is pushed through the esophagus by a wavelike contraction called the peristalsis. b. Near the end of the esophagus, there is a part called the lower esophageal sphincter, that closes after the food exits to prevent them from coming back up. i. *esophagus joins the stomach at the cardiac region 3. Stomach. a. The food from the esophagus is mixed with gastric juice, to form a pasty material called chime, which then passes into the fundus, and body of the stomach to the pyloric antrum, and then pyloric sphincter to leave the stomach and enter the first phase of the small intestine. b. The stomach has three layers of smooth muscles ( longitudinal, circular, and oblique smooth muscles, and that the inner lining of the stomach has large folded ridges, the gastric rugae.
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4. GI tract(also known as the digestive tract), including the stomach, consists of four major tissue layer, the mucosa, submucosa, muscularis externa, and adventitia. a. The mucosa is the innermost layer, facing the lumen. Just to the outside of the mucosa is the submucosa, which is the major connective tissue layer. This is followed by the muscularis externa, consisting of two or three layers of smooth muscles. A thin consecutive tissue layer, the adventitia covers the GI tract. 5.
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This note was uploaded on 09/13/2011 for the course BIO 26 taught by Professor Fortes during the Spring '11 term at UCSD.

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BIO26 CHAPTER 14 - Chapter 14 Digestive system. 1. The...

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