Digestive Tract: Oral Cavity
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Questions and Answers

What type of epithelium lines the oral cavity?

  • Keratinized stratified columnar epithelium
  • Simple cuboidal epithelium
  • Nonkeratinized stratified squamous epithelium (correct)
  • Pseudostratified epithelium

    • What is the function of amelogenin in the development of teeth?

  • Serves as a template for enamel crystal formation
  • Regulates the activity of odontoblasts
  • Guides the growth of dentinal tubules
  • Guides the calcification of enamel rods (correct)

    • What is the main component of the tooth root and neck?

  • Pulp
  • Enamel
  • Dentin (correct)
  • Cementum

    • What type of papillae lacks epithelial taste buds?

    <p>Filiform papillae</p> Signup and view all the answers

    What is the main function of the periodontal ligament?

    <p>Anchors the tooth to the jaw socket</p> Signup and view all the answers

    What is the structure that contains the vascularized and innervated pulp?

    <p>Pulp cavity</p> Signup and view all the answers

    What is the function of odontoblasts?

    <p>Secretes dentin</p> Signup and view all the answers

    What type of epithelium covers the hard palate and gingiva?

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

    What type of epithelium lines the esophagus at its superior end?

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

    What type of muscle fibers are present in the muscularis of the esophagus at its superior end?

    <p>Only striated muscle</p> Signup and view all the answers

    What layer of the digestive tract consists of loose connective tissue and smooth muscle fibers?

    <p>Lamina propria</p> Signup and view all the answers

    What type of epithelium is present in the esophagus at the esophagogastric junction?

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

    What is the outermost layer of the esophagus?

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

    What is the primary function of the mucus secreted by surface mucous cells in the stomach?

    <p>To protect the stomach lining from acid and enzymes</p> Signup and view all the answers

    Which cell type is responsible for producing intrinsic factor for vitamin B12 uptake?

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

    What is the function of chief cells in the gastric glands?

    <p>To secrete pepsinogen</p> Signup and view all the answers

    What is the location of chief cells in the gastric glands?

    <p>In the lower half of the gastric glands</p> Signup and view all the answers

    What is the function of enteroendocrine cells in the stomach?

    <p>To release peptide hormones</p> Signup and view all the answers

    What type of cells are present in the mucosa of the stomach cardiac and pyloric regions?

    <p>Columnar mucous cells</p> Signup and view all the answers

    What is the function of the gastric pits in the stomach?

    <p>To lead into branching gastric glands</p> Signup and view all the answers

    What is the location of pluripotent stem cells in the gastric glands?

    <p>In the neck regions of the gastric glands</p> Signup and view all the answers

    What is the function of mucous neck cells?

    <p>To secrete less alkaline mucus</p> Signup and view all the answers

    What is the main difference between the mucosa of the stomach fundus and body and the mucosa of the stomach cardiac and pyloric regions?

    <p>The type of glands present</p> Signup and view all the answers

    What is the function of stem cells in the intestinal glands?

    <p>To produce columnar epithelial cells for nutrient absorption</p> Signup and view all the answers

    What is the function of the autonomic submucosal plexus?

    <p>To regulate smooth muscle in the lamina propria and muscularis mucosae</p> Signup and view all the answers

    What is the function of enterocytes in the small intestine?

    <p>To absorb nutrients through transcytosis</p> Signup and view all the answers

    What is the role of the lacteals in the small intestine?

    <p>To release chylomicrons into the lymphatic system</p> Signup and view all the answers

    What is the function of the autonomic myenteric plexus?

    <p>To regulate strong peristalsis</p> Signup and view all the answers

    What is the structure of the mucosa in the small intestine?

    <p>Simple columnar epithelium with simple tubular glands</p> Signup and view all the answers

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

    <p>To produce defensins for immune function</p> Signup and view all the answers

    What is the location of Peyer patches in the small intestine?

    <p>In the ileum</p> Signup and view all the answers

    What is the function of the teniae coli in the large intestine?

    <p>To aid in peristaltic movement of feces</p> Signup and view all the answers

    What type of epithelium lines the anus?

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

    What is the function of the muscularis in the anal canal?

    <p>To form the internal and external anal sphincters</p> Signup and view all the answers

    What is the name of the glands found in the mucosa of the large intestine?

    <p>Intestinal glands</p> Signup and view all the answers

    What is the main component of the large intestine?

    <p>Colon, rectum, and anus</p> Signup and view all the answers

    What is the main function of the lubricant goblet cells in the large intestine?

    <p>Uptake of water and electrolytes</p> Signup and view all the answers

    What is the structure that controls the movement of feces to the rectum in the large intestine?

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

    What is the type of epithelium that lines the rectum?

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

    What is the function of the muscularis in the anal canal?

    <p>Regulation of the anal sphincter</p> Signup and view all the answers

    What is the name of the glands found in the mucosa of the large intestine?

    <p>Intestinal glands</p> Signup and view all the answers

    Study Notes

    Oral Cavity Structure

    • Lined primarily by mucosa with nonkeratinized stratified squamous epithelium
    • Hard palate and gingiva have keratinized stratified squamous epithelium

    Lingual Papillae

    • Four types of papillae on the dorsal surface of the tongue: filiform, foliate, fungiform, and large vallate papillae
    • Filiform papillae have keratinized epithelium, while others have nonkeratinized epithelium
    • All lingual papillae, except filiform, have epithelial taste buds on their sides

    Taste Buds

    • Contain chemosensory gustatory cells with synapses to basal sensory innervation
    • Support cells and an apical taste pore are present in taste buds

    Tooth Structure

    • Each tooth has enamel covering its crown and neck
    • Enamel is made up of parallel enamel rods, guided by the protein amelogenin
    • Enamel rods are secreted by columnar epithelial cells called ameloblasts in the enamel organ of the embryonic tooth bud

    Dentin and Pulp Cavity

    • Dentin makes up the roots and extends into the neck of the tooth
    • The pulp cavity is vascularized and innervated, with a central cavity within the dentin
    • Predentin is secreted as elongated d entinal tubules from tall odontoblasts that line the pulp cavity
    • Apical odontoblast processes extend between the tubules

    Periodontium

    • Consists of a thin layer of bonelike cementum surrounding dentin of the roots
    • The periodontal ligament binds the cementum to alveolar bone on the jaw socket

    Layers of the Digestive Tract

    • The digestive tract from the esophagus to the rectum has four major layers: mucosa, submucosa, muscularis, and adventitia or mesothelium-covered serosa.

    Mucosa Layer

    • The mucosa layer varies regionally along the tract, consisting of a lining epithelium on a lamina propria of loose connective tissue and smooth muscle fibers extending from the muscularis mucosae layer.

    Esophagus

    • The esophagus has nonkeratinized stratified squamous epithelium in its mucosa layer.
    • The muscularis layer of the esophagus is striated at its superior end and smooth at its inferior end, with mixed fiber types in the middle.
    • Most of the outer layer of the esophagus is adventitia, which merges with other tissues of the mediastinum.
    • At the esophagogastric junction, the stratified squamous epithelium changes abruptly to simple columnar epithelium that invaginates into the lamina propria as many branched tubular glands.

    Stomach Regions

    • The stomach has four major regions: superior cardia, inferior pylorus, fundus, and body.
    • The fundus and body are histologically similar, as are the superior cardia and inferior pylorus.

    Mucosa of the Stomach Fundus and Body

    • The mucosa is penetrated by numerous gastric pits.
    • Gastric pits are lined with surface mucous cells and lead into branching gastric glands.
    • Surface mucous cells secrete a thick layer of viscous mucus with bicarbonate ions, protecting the cells and underlying lamina propria.

    Gastric Glands

    • Gastric glands are lined by epithelium with four major cell types and pluripotent stem cells.
    • The four major cell types are:
      • Mucous neck cells, which produce less alkaline mucus and are immature precursors of surface mucous cells.
      • Parietal cells, which produce HCl and intrinsic factor for vitamin B12 uptake.
      • Chief (zymogenic) cells, which secrete pepsinogen activated by low pH in the lumen to form pepsin.
      • Enteroendocrine cells, which release peptide hormones to regulate neighboring tissues during food digestion.

    Mucosa of the Stomach Cardiac and Pyloric Regions

    • The mucosa has branching cardial and pyloric glands.
    • These glands consist almost entirely of columnar mucous cells, lacking parietal and chief cells.

    Small Intestine Structure

    • The small intestine has three regions: duodenum, jejunum, and ileum.
    • The duodenum has large mucous glands in the submucosa called duodenal glands.
    • The ileum has large mucosal and submucosal Peyer patches.

    Mucosa Composition

    • The mucosa has millions of projecting villi.
    • Villi are covered with simple columnar epithelium over cores of lamina propria.
    • Intervening simple tubular intestinal glands (or crypts) are found in the mucosa.

    Cellular Composition

    • Stem cells in the glands produce columnar epithelial cells of villi.
    • Main cell types produced by stem cells: goblet cells, enterocytes for nutrient absorption, and Paneth cells (defensin-producing cells).
    • Paneth cells are located deep in the glands.

    Nutrient Absorption

    • Sugars and amino acids produced by carbohydrate and polypeptide digestion in the glycocalyx undergo transcytosis through enterocytes for uptake by capillaries.
    • Lipid digestion products associate with bile salts, are taken up by enterocytes, and are converted to triglycerides and lipoproteins.
    • Chylomicrons are released from enterocytes for uptake by lacteals in the core of each villus.

    Muscle Function

    • Smooth muscle in the lamina propria and muscularis mucosae helps move villi and propel lymph through lacteals.
    • Smooth muscle in the muscularis (inner circular and outer longitudinal layers) produces strong peristalsis under the control of the autonomic myenteric (Auerbach) plexus.

    Large Intestine Structure

    • The large intestine has three main regions: cecum, colon, and rectum.
    • The colon has four distinct portions: ascending, transverse, descending, and sigmoid.

    Large Intestine Function

    • Millions of short simple tubular intestinal glands line the mucosa, producing lubricant and absorptive cells.
    • These glands facilitate the uptake of water and electrolytes.

    Muscularis Function

    • The outer longitudinal layer of the muscularis is divided into three bands of smooth muscle called teniae coli.
    • Teniae coli aid in the peristaltic movement of feces towards the rectum.

    Anal Canal Structure

    • The anal canal marks a sudden shift from simple columnar epithelium lining the rectum to stratified squamous epithelium of the skin at the anus.

    Anal Sphincter Control

    • The circular layer of the rectum's muscularis forms the internal anal sphincter.
    • The external anal sphincter, composed of striated muscle, provides additional control.

    Large Intestine Structure

    • The large intestine has three main regions: cecum, colon, and rectum.
    • The colon has four distinct portions: ascending, transverse, descending, and sigmoid.

    Large Intestine Function

    • Millions of short simple tubular intestinal glands line the mucosa, producing lubricant and absorptive cells.
    • These glands facilitate the uptake of water and electrolytes.

    Muscularis Function

    • The outer longitudinal layer of the muscularis is divided into three bands of smooth muscle called teniae coli.
    • Teniae coli aid in the peristaltic movement of feces towards the rectum.

    Anal Canal Structure

    • The anal canal marks a sudden shift from simple columnar epithelium lining the rectum to stratified squamous epithelium of the skin at the anus.

    Anal Sphincter Control

    • The circular layer of the rectum's muscularis forms the internal anal sphincter.
    • The external anal sphincter, composed of striated muscle, provides additional control.

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    Description

    This quiz covers the anatomy and features of the oral cavity in the digestive tract, including the types of epithelium and lingual papillae on the tongue.

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