Digestive System II with px

Digestive System II with px - Digestive System II:...

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Digestive System II: Esophagus and Gastrointestinal Tract (Chapter 17, pages 518 – 575) A. General histology of the digestive tract (cross-section): figure 17.1, page 519
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1. Mucosa a. Epithelial lining (mucous membrane): lies on basal lamina; endodermal origin b. Lamina Propria: loose areolar CT; rich in blood and lymph capillaries; lymphatic tissue may be present; lymphocytes and wandering cells c. Muscularis mucosa: smooth muscles; usually arranged in inner circular and outer longitudinal; layer begins at the esophagus 2. Submucosa: course areolar to dense irregular CT with prominent elastic fibers; contains plexuses of larger blood vessels and nerves (Meissner’s nerve plexus) 3. Muscularis externa: at least 2 layers of smooth muscles; layers arranged in inner circular and outer longitudinal; Auerbach’s nerve plexus; muscle in oral cavity and upper esophagus is skeletal muscle 4. Serosa (adventitia): outermost layer of dense, irregular CT or elastic areolar CT; adventitia-blends with surrounding tissue; serosa lined by mesothelium B. Esophagus: Figure 17.2, page 522. Approx. 25 cm; muscular tube with a stellate lumen; transports foodstuffs from the mouth to the stomach 1. Mucosa a. Stratified squamous epithelium, nonkeratinized
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Lamina propria: areolar with lymphocytes; mucous secreting cardiac glands located in the upper and lower ends c. Muscularis mucosa: thick; inner layer incomplete; outer longitudinal 2. Submucosa: coarse collagenous and elastic fibers; esophageal glands proper (mucous). Figure 17.4, page 523 3. Muscularis externa: a Inner circular and outer longitudinal b. Upper third skeletal muscle; middle third contains smooth muscle bundles which are mixed with skeletal fibers and the proportion decreases gradually until only smooth muscle is present in the lower third c. Pharyngeoesophageal and esophagogastric sphincters. Middle esophagus: muscularis externa 4. Adventitia a blends with surrounding structures; esophagus below diaphragm is covered by serosa C. Stomach: figure 17.5, page 524 1. Gross anatomy: lesser and greater curvatures; gastroesophageal and pyloric sphincter; 4 major anatomical regions: fundus, cardia, body, pyloris 2. Gastric rugae: mucosa and submucosa thrown into folds
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Digestive System II with px - Digestive System II:...

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