Medical Sciences 3999A/B/Y Lecture Notes - Lecture 24: Muscularis Mucosae, Lamina Propria, Gastric Pits
20 Feb 2020
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Document Summary
Except for oral cavity, digestive tube has uniform histological organization. Differentiated into four major organs: esophagus 2) stomach 3) small intestine 4) large intestine. Each organ is made up of 4 concentric layers (following the pharynx): Lining epithelium: invaginates to form glands, extending to: Submucosa - submucosal glands, blood vessels and nerves, collagen. Ducts - secretions transported (i. e. from liver and pancreas) through duodenum to lumen. Lamina propria: vascularized loose ct with aggregations of lymphocytes. Scattered immunocompetent cells (i. e. lymphocytes, plasma cells and macrophages) Smooth muscle: thin layer of muscularis mucosae ii. iii. Dense irregular ct with large blood vessels, lymphatics. Muscularis externa: smooth muscle cells spirally oriented; divided into 2 sublayers: i. ii. Internal sublayer: closer to lumen - oriented in circular direction. Also contains myenteric (auerbach"s) nerve plexus between 2 sublayers. Ct also present between 2 sublayers: contains blood and lymph vessels. Thin layer of loose ct with blood and lymph vessels, and adipose.
