Digestive System Histology PDF

Digestive Function Chemical digestion—a series of hydrolysis reactions that breaks dietary macromolecules into their monomers (residues) – Carried out by digestive enzymes produced by salivary glands, stomach, pancreas, and small intestine – Results...

Digestive Function Chemical digestion—a series of hydrolysis reactions that breaks dietary macromolecules into their monomers (residues) – Carried out by digestive enzymes produced by salivary glands, stomach, pancreas, and small intestine – Results Polysaccharides into monosaccharides Proteins into amino acids Fats into monoglycerides and fatty acids Nucleic acids into nucleotides Some nutrients are present in a usable form in ingested food and can be directly absorbed – Vitamins, amino acids, minerals, cholesterol, and water ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy Digestive system has two subdivisions: digestive tract and accessory organs Digestive tract (alimentary canal) – 30 ft long muscular tube extending from mouth to anus – Mouth, pharynx, esophagus, stomach, small intestine, and large intestine – Gastrointestinal (GI) tract is the stomach and intestines Accessory organs – Teeth, tongue, salivary glands, liver, gallbladder, and pancreas ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  The Digestive System Copyright © McGraw-Hill Education. Permission required for reproduction or display. ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 2 Digestive tract is open to environment at both ends Most material in it has not entered the body tissues – Considered to be external to the body until it is absorbed by the epithelial cells of the alimentary canal On a strict sense, defecated food residue was never in the body ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 3 Most of digestive tract follows a basic structural plan with the digestive tract wall consisting of layers: – Mucosa Epithelium Lamina propria Muscularis mucosae – Submucosa – Muscularis externa Inner circular layer Outer longitudinal layer – Serosa Areolar tissue Mesothelium ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 4 Mucosa (mucous membrane)—lines the lumen and consists of: – Inner epithelium Simple columnar in most of digestive tract Stratified squamous from mouth through esophagus, and in lower anal canal – Lamina propria: loose connective tissue layer – Muscularis mucosa: thin layer of smooth muscle Tenses mucosa creating grooves and ridges that enhance surface area and contact with food Improves efficiency of digestion and nutrient absorption – Mucosa-associated lymphatic tissue (MALT): the mucosa exhibits an abundance of lymphocytes and lymphatic nodules ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 5 Submucosa—thicker layer of loose connective tissue – Contains blood vessels, lymphatic vessels, a nerve plexus, and in some places mucus- secreting glands that dump lubricating mucus into the lumen – MALT extends into the submucosa in some parts of the GI tract ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 6 Muscularis externa—consists of usually two layers of muscle near the outer surface – Inner circular layer In some places, this layer thickens to form valves (sphincters) that regulate the passage of material through the tract – Outer longitudinal layer – Responsible for the motility that propels food and residue through the tract ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 7 Serosa—composed of a thin layer of areolar tissue topped by simple squamous mesothelium – Begins in the lower 3 to 4 cm of the esophagus – Ends just before the rectum – Adventitia: fibrous connective tissue layer that binds and blends the pharynx, most of the esophagus, and the rectum into adjacent connective tissue of other organs ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 8 Enteric nervous system—nervous network in esophagus, stomach, and intestines that regulates digestive tract motility, secretion, and blood flow – Thought to have over 100 million neurons – Can function independently of central nervous system But CNS usually exerts influence on its action – Often considered part of autonomic nervous system ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  General Anatomy 9 Enteric nervous system is composed of two networks of neurons – Submucosal plexus: in submucosa Controls glandular secretions of mucosa Controls movements of muscularis mucosae – Myenteric plexus: parasympathetic ganglia and nerve fibers between the two layers of the muscularis externa Controls peristalsis and other contractions of muscularis externa ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Mesentery 25-12 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Relationship to the Peritoneum 1 Mesenteries—connective tissue sheets that suspend stomach and intestines from abdominal wall – Looseness allows stomach and intestines to undergo strenuous contractions with freedom of movement in the abdominal cavity – Hold abdominal viscera in proper relationship to each other – Prevent intestines from becoming twisted and tangled by changes in body position and by its own contractions – Provide passage of blood vessels and nerves that supply digestive tract ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Visceral Parietal Peritone Peritoneu peritoneum peritoneu al m m cavity Lesser Mesentery Greater omentu of small omentu m intestine Peritoneum m Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Alimentary Canal Wall Mucosa Submucosa Muscularis externa Serosa Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Tissue Layers of the Digestive Tract Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 25.2 ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Mesentery 25-17 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Visceral Parietal Peritone Peritoneu peritoneum peritoneu al m m cavity Lesser Mesentery Greater omentu of small omentu m intestine Peritoneum m Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Lesser and Greater Omentum 25-19 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Greater and Lesser Curvatures of the Stomach Lesser Greater 25-20 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Serous Membranes 1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 25.3a ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Serous Membranes 2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 25.3b ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Cheeks and Lips Orbicularis oris Buccinator 25-23 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  The Tongue 4 Copyright © McGraw-Hill Education. Permission required for reproduction or display. (a) Superior (b) Frontal section, view anterior view Figure 25.5 ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-3 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-4 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-5 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Tongue 25-28 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Palate and Palatine Tonsil Hard palate Soft palate Uvula Palatine tonsil 25-29 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Salivary Glands Parotid Sublingual Submandibular Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  The Extrinsic Salivary Glands Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 25.9 ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Histology of Salivary Glands 1 Compound tubuloacinar glands – Branched ducts ending in acini Mucous cells secrete mucus Serous cells secrete thin fluid rich in enzymes and electrolytes Mixed acinus has both mucous and serous cells ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Histology of Salivary Glands 2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Figure 25.10 b: © McGraw-Hill Education/Dennis Strete, photographer ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Pharynx Nasopharynx Oropharynx Laryngopharynx Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Surface Projection of Esophagus Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Esophagus Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-12 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-13 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Esophagus Mucosa LM: Low Magnification Adventitia Photos © McGraw-Hill Education Epithelium Muscularis Submucosa Muscularis externa mucosae ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Stomach Esophagus Cardia Fundus Body Pyloric Pyloric Pyloric antrum canal orifice Duodenum Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Stomach Wall Musculature Lower Pyloric Stomach esophageal sphincter musculature sphincter Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Stomach Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Gross Anatomy of the Stomach 3 Copyright © McGraw-Hill Education. Permission required for reproduction or display. ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Gross Anatomy of the Stomach 4 Copyright © McGraw-Hill Education. Permission required for reproduction or display. ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Mucosa of the Stomach Wall 1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. (a) Stomach wall ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-15 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-17 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Stomach LM:Photos High Magnification © McGraw-Hill Education Chief cells Parietal cells ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Stomach Gastric pits SEM: Low Magnification Surface epithelium Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Mucosa of the Stomach Wall 2 Copyright © McGraw-Hill Education. Permission required for reproduction or display. (d) Gastric pits d: © Steve Gschmeissner/Science Source Figure 25.13d ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-18 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Figure 15-19 Copyright © McGraw-Hill Companies ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Gross Anatomy of the Small Intestine 1 ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Small Intestine SEM: Low Magnification Villi of duodenum ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Intestinal Microvilli Microvilli TEM: High Magnification Absorptive cell of ileum ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Copyright © McGraw-Hill Education. Permission required for Intestinal Villi reproduction or display. 2 a: © Meckes/Ottawa/Science Source; b: © McGraw-Hill Education/Dennis ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Photos © McGraw-Hill Education Jejenum LM: Medium Magnification Brush border Intestinal Paneth cells glands Villi Epithelium Goblet cells Lacteal ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Jejenum LM: High Magnification Intestinal gland Paneth cells Secretory granules of paneth cells ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Mucosa Submucosa Ileum LM: Low Magnification Photos © McGraw-Hill Education Villi Plica circulares Peyer patches Intestinal glands Lacteals ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Goblet cells Ileum LM: High Magnification Epithelium of ileum Surface absorptive cell Brush border Villus Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Ileum TEM: Medium Magnification Brush border Surface absorptive cell Goblet cell Nucleus of goblet cell ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Peyer Patches of Ileum LM: Medium Magnification Intestinal mucosa of Lymphoid nodule of ileum ileum Submucosa of ileum Muscularis externa of ileum Peyer patches of ileum Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Large Intestine Gross Anatomy Copyright © McGraw-Hill Education. Permission required for reproduction or display. (a) Gross anatomy ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Large Intestine Photos © McGraw-Hill Education Ascending Rt. colic Transverse colon flexure colon Lt. colic Descending Sigmoid colon flexure colon ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Colon X-ray Photos © McGraw-Hill Education Cecum Ascending colon Transverse colon Sigmoid colon Rectum Descending colon ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Rectum and Anus External Rectum Anal canal anal sphincter Internal anal Anal columns Transverse rectal fold sphincter 25-66 Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Haustra Taeniae coli Photos © McGraw-Hill Education Omental (epiploic) appendages ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  The Large Intestine – Anal Canal Copyright © McGraw-Hill Education. Permission required for reproduction or display. (b) Anal canal Figure 25.32b ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Large Intestine Histology Photos © McGraw-Hill Education Intestinal Goblet glands cells ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  Colon LM: Low Magnification Mucosa of colon Opening of intestinal glands Intestinal glands of colon Submucosa Muscularis mucosae of colon Photos © McGraw-Hill Education ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior Mucosa of colon Colon Intestinal glands LM: Medium Magnification Photos © McGraw-Hill Education Opening of Muscularis intestinal gland mucosae Submucosa Muscularis externa Goblet cells ©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior