Histology of Gastrointestinal Tract
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Questions and Answers

What is the type of epithelium found in the mucosa of the esophagus?

  • Pseudostratified columnar epithelium
  • Stratified squamous non-keratinized epithelium (correct)
  • Stratified columnar epithelium
  • Simple cuboidal epithelium

    • What type of fibers are found in the upper one-third of the muscularis externa of the esophagus?

  • Skeletal muscle fibers (correct)
  • Cardiac muscle fibers
  • Smooth muscle fibers
  • Mixed muscle fibers

    • What is the name of the plexus found in the submucosa of the esophagus?

  • Myenteric plexus
  • Plexus of Henle
  • Plexus of Auerbach
  • Plexus of Meissner (correct)

    • What is the type of epithelium found in the mucosa of the stomach?

    <p>Simple columnar epithelium</p> Signup and view all the answers

    What are the three histological regions of the stomach?

    <p>Cardiac, fundic, and pyloric regions</p> Signup and view all the answers

    What is the type of epithelium found in the serosa of the stomach?

    <p>Simple squamous epithelium</p> Signup and view all the answers

    What is the primary function of the small intestine?

    <p>Absorption of nutrients</p> Signup and view all the answers

    What percentage of nutrient absorption occurs in the small intestine?

    <p>90%</p> Signup and view all the answers

    Which segment of the small intestine is responsible for most chemical digestion and nutrient absorption?

    <p>Jejunum</p> Signup and view all the answers

    What is the name of the deep transverse folds in the intestinal lining?

    <p>Plicae circularis</p> Signup and view all the answers

    What is the function of goblet cells in the small intestine?

    <p>Production of mucins</p> Signup and view all the answers

    What is the name of the central lymph capillary in each villus?

    <p>Lacteal</p> Signup and view all the answers

    What is the primary function of enteroendocrine cells in the small intestine?

    <p>Production of intestinal hormones</p> Signup and view all the answers

    What is the name of the areas of lymphoid tissue in the submucosa?

    <p>Peyer's patches</p> Signup and view all the answers

    What is the function of villi in the small intestine?

    <p>To absorb large particles into the body</p> Signup and view all the answers

    What is the main function of the large intestine?

    <p>To reabsorb water and compact intestinal contents</p> Signup and view all the answers

    What is the name of the first portion of the large intestine?

    <p>Cecum</p> Signup and view all the answers

    What is the name of the muscle bands that run along the outer surfaces of the colon?

    <p>Taeniae coli</p> Signup and view all the answers

    What is the purpose of the haustra in the colon?

    <p>To permit expansion and elongation of the colon</p> Signup and view all the answers

    What is the main difference between the small intestine and the large intestine?

    <p>The large intestine has a larger diameter and thinner wall than the small intestine</p> Signup and view all the answers

    What is the function of the muscularis externa in the small intestine?

    <p>To facilitate absorption and lymph movement</p> Signup and view all the answers

    What is the name of the glands found in the submucosa of the duodenum?

    <p>Brunner's glands</p> Signup and view all the answers

    What type of cells are mostly found in the proximal portions of gastric glands?

    <p>Parietal cells</p> Signup and view all the answers

    Which of the following cells secrete pepsinogen?

    <p>Chief cells</p> Signup and view all the answers

    What is the function of enteroendocrine cells in the gastric gland?

    <p>Secrete serotonin, histamine and gastrin</p> Signup and view all the answers

    What is the main component of the muscularis externa in the pyloric region of the stomach?

    <p>Inner circular and outer longitudinal layer</p> Signup and view all the answers

    What is the main function of the gastric glands in the fundus and body of the stomach?

    <p>To secrete gastric juice, mucus, and gastrin</p> Signup and view all the answers

    Which of the following layers of the stomach contains blood vessels, lymphatics, and Meissner's plexus?

    <p>Submucosa</p> Signup and view all the answers

    What is the enzyme converted from pepsinogen in the gastric lumen?

    <p>Pepsin</p> Signup and view all the answers

    What is the main characteristic of the pyloric glands in the lamina propria of the pyloric region?

    <p>They extend half the thickness of the mucosa</p> Signup and view all the answers

    What is characteristic of the mucosa of the large intestine?

    <p>Abundance of goblet cells</p> Signup and view all the answers

    What is the function of the mucosa in the large intestine?

    <p>Provides lubrication for fecal material</p> Signup and view all the answers

    What is characteristic of the Crypts of Lieberkuhn in the large intestine?

    <p>They are dominated by goblet cells</p> Signup and view all the answers

    What is characteristic of the muscularis externa in the large intestine?

    <p>It forms taenia coli</p> Signup and view all the answers

    What is characteristic of the vermiform appendix?

    <p>It has a large accumulation of lymphoid tissue</p> Signup and view all the answers

    What is characteristic of the rectum?

    <p>It has a continuous coat of longitudinal muscle</p> Signup and view all the answers

    What is characteristic of the anal canal?

    <p>It has a stratified squamous non-keratinized epithelium</p> Signup and view all the answers

    What is characteristic of the mucosa in the anal canal?

    <p>It has characteristic longitudinal folds</p> Signup and view all the answers

    Study Notes

    Basic Histological Layers of the Digestive System

    • The digestive system consists of four main layers: Mucosa, Submucosa, Muscularis, and Serosa
    • Mucosa: composed of Epithelium, Lamina Propria, and Muscularis Mucosae
    • Submucosa: contains Submucosal plexus (“Plexus of Meissner”)
    • Muscularis: contains Myenteric plexus
    • Serosa: outermost layer, composed of a thin layer of connective tissue and epithelium

    Esophagus

    • Mucosa: Stratified squamous non-keratinized epithelium
    • Submucosa: contains Meissner's plexus and oesophageal glands
    • Muscularis externa: composed of skeletal fibers (upper one-third), mixed fibers (middle one-third), and smooth fibers (lower one-third)
    • Adventitia: loose connective tissue

    Stomach

    • Divided into three histological regions: Cardiac, Fundic, and Pyloric
    • Mucosa: simple columnar epithelium with gastric pits
    • Gastric glands:
      • Found in fundus and body of stomach
      • Secrete gastric juice, mucus, and gastrin
      • Each gastric pit communicates with several gastric glands
      • Two types of secretory cells: parietal cells and chief cells
    • Cells of fundic region:
      • Mucous neck cells
      • Parietal (oxyntic) cells
      • Chief (peptic/zymogen) cells
      • Enteroendocrine cells
      • Undifferentiated cells
    • Parietal cells:
      • Secrete intrinsic factor and hydrochloric acid (HCl)
      • Mostly found in proximal portions of glands
    • Chief cells:
      • Secrete pepsinogen (inactive proenzyme)
      • Most abundant near base of gastric gland
      • Pepsinogen is converted by HCl in the gastric lumen to pepsin (active proteolytic enzyme)

    Small Intestine

    • Divided into three segments: Duodenum, Jejunum, and Ileum
    • Mucosa:
      • Characterized by Plicae circularis (valves of Kerkring)
      • Villi and Microvilli
      • Goblet cells (few)
      • Crypts of Lieberkuhn (intestinal glands)
      • Glands are lined by columnar cells, goblet cells, Paneth cells, and enteroendocrine cells
    • Plays key role in digestion and absorption of nutrients
    • 90% of nutrient absorption occurs in the small intestine
    • Segments of the S.I.:
      • Duodenum: 25 cm long, receives chyme from stomach, digestive secretions from pancreas and liver
      • Jejunum: 2.5 meter long, middle segment, location of most chemical digestion and nutrient absorption
      • Ileum: 3.5 meter long, final segment, joins large intestine at ileocecal valve

    Intestinal Folds and Projections

    • Structural modifications of the small intestine wall increase surface area
    • Plicae: largest, deep transverse (circular) folds in intestinal lining, permanent features
    • Intestinal Villi: series of fingerlike projections of mucosa, covered with simple columnar epithelium, which have many plasma membrane projections called microvilli
    • All serve to increase surface area for absorption (altogether by 600x)

    Large Intestine

    • Also called large bowel
    • Horseshoe-shaped, about 1.5 meters long and 7.5 cm wide
    • Extends from end of ileum to anus
    • Lies inferior to stomach and liver
    • Functions:
      • Reabsorption of water (the last 15-20%)
      • Compaction of intestinal contents into feces
      • Absorption of important vitamins produced by bacteria
      • Storage of fecal material prior to defecation
    • Parts of the Large Intestine:
      • Cecum: pouchlike first portion, has wormlike appendix projecting from it
      • Colon: largest portion
      • Rectum: last 15 cm of digestive tract
      • Anal canal
    • Mucosa:
      • Absence of Plicae circulares and villi
      • Presence of Microvilli
      • Presence of Crypts of Lieberkuhn
      • Presence of Goblet cells in large number

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    Description

    This quiz covers the basic histological layers of the digestive system, including the esophagus, mucosa, submucosa, muscularis, and serosa.

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