Exam 4 Review - Anatomy Exam 4 Digestive System Major...

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Anatomy Exam 4 Digestive System Major functions of the Gi tract: secretion (hormones, digestive enzymes) and motility (muscle activity). Functions of the Digestive System 1. ingestion: conscious placement of food material into the mouth 2. mechanical processing: grinding and chewing with teeth (mastication) and squashing and compacting with tongue 3. digestion: chemical breakdown of food via various digestive enzymes 4. secretion (moving things into a lumen or space – stuff is still in body) : release of water, acids, mucus, enzymes, buffers and salts by the digestive tract epithelium and accessory organs 5. absorption (mainly in small and large intestine): movement of organic substrates, electrolytes, vitamins and water across the digestive tract epithelium 6. excretion (removing things from the body): removal of waste products from body fluids (defecation) 7. protection: of underlying tissues from acids, enzymes and bacteria The Digestive Organs and the Peritoneum - digestive organs are within the peritoneal cavity; cavity is bound by serous membranes (parietal and visceral peritoneum); peritonitis - mesenteries are peritoneal folds; vasculature, nerves, stabilization - retroperitoneal organs develop outside of the peritoneal cavity Gi tract is line with a thick muscle made of 4 layers (visceral to parietal) – Mucusa: epithelial lining  very regenerative (simple columnar with goblet cells (unicellular exocrine gland that releases mucus) : lamina propria  loose connective tissue that contain a lot of glands for absorption : muscularis mucosae regulate conformation of organization submuscusa (dense connective tissue): submucusal plexus (Meissner’s plexus)  nerve network responsible for secretory and motility purpose, found between submucosa and muscularis externa
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muscularis externa has an inner layer of muscle (allow you to change the diameter) and outer longitudinal layer (allow you to make it flatter to make it wider)  doing both at the same time allow for movement myenteric plexus (auerbach’s plexus)  motility of muscularis externa (GI tract)/ found between the inner circular and outer longitudinal layer of muscle serosa  loose connective tissue with a visceral perotenium (loose connective with NO visceral perotenium is not a serosa) most of your esophagus is adventia, so is your duodenum and rectum anal junction  loose connective tissue with no visceral perotenium Most abundant tissue in the GI tract – simple columnar epithelium No goblet cells in the stomach. ** Degluttition – the act of swallowing - pharynx is skeletal muscle - upper 1/3 esophagus is skeletal but bottom 2/3 is all smooth muscle esophagus is controlled by enteric NS via reflexes but is modulated by autonomic NS - Enteric system is controlling food after it leaves the upper 1/3 of the esophagus.
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