Microvilli and Digestive System Functions
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Questions and Answers

What type of muscle is found in the muscularis layer of the stomach?

  • Smooth muscle (correct)
  • Skeletal muscle
  • Striated muscle
  • Cardiac muscle

    • Which region of the stomach has an abundance of mucus glands?

  • Glandular region
  • Cardia region (correct)
  • Fundus region
  • Pylorus region

    • What is the function of chief cells in the stomach?

  • Secretion of mucus
  • Secretion of HCl
  • Secretion of gastrin
  • Secretion of pepsinogen (correct)

    • What is the name of the folds in the mucosal layer of the glandular stomach?

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

    Which type of teeth continue to grow after eruption?

    <p>Hypsodont teeth</p> Signup and view all the answers

    What is the function of parietal cells in the stomach?

    <p>Secretion of HCl</p> Signup and view all the answers

    Which layer of the esophagus contains mucous glands?

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

    What is the name of the structure that increases the surface area of the stomach?

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

    What type of epithelium is found in the mucosa of the oral cavity?

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

    What is the main function of the parotid gland?

    <p>To produce serous secretions</p> Signup and view all the answers

    What is the function of the cementum in teeth?

    <p>To cover the entire external surface of the tooth below the gumline</p> Signup and view all the answers

    What is the function of the odonotoblasts in teeth?

    <p>To form the dentin of the tooth</p> Signup and view all the answers

    What is the characteristic of brachydont teeth?

    <p>They are short and cease to grow after eruption</p> Signup and view all the answers

    What is the function of the periodontal ligament in teeth?

    <p>To hold the tooth in place in the socket</p> Signup and view all the answers

    What is the function of the fibroblasts in the periodontal ligament?

    <p>To form the periodontal ligament</p> Signup and view all the answers

    What is the function of the mucosa in the oral cavity?

    <p>To provide a protective layer for the oral cavity</p> Signup and view all the answers

    What is the primary function of the Brunner's glands in the submucosa of the duodenum?

    <p>Producing alkaline mucus to protect from acidic chyme</p> Signup and view all the answers

    What type of epithelium is found in the anus?

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

    What is the primary function of the hepatocytes in the liver?

    <p>All of the above</p> Signup and view all the answers

    What type of epithelium is found in the ileum?

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

    What is the function of the Kupffer cells in the liver?

    <p>To remove aged blood cells and pathogens from the blood</p> Signup and view all the answers

    What is the function of the Ito cells in the liver?

    <p>To metabolize vitamin A and produce collagen</p> Signup and view all the answers

    What is the main function of the large intestine?

    <p>Water absorption and electrolyte balance</p> Signup and view all the answers

    What is the function of the omasum in the digestive system?

    <p>Squeezing and liquifying ingesta to move it to the abomasum</p> Signup and view all the answers

    What is the primary function of M cells in the digestive system?

    <p>Sampling antigens from the lumen environment</p> Signup and view all the answers

    What is the function of the submucosal gland in the digestive system?

    <p>Secretion of mucus to facilitate movement of particles</p> Signup and view all the answers

    What is the function of the myenteric plexus in the digestive system?

    <p>Controlling GI tract motility</p> Signup and view all the answers

    What is the function of the hepatic acinus in the digestive system?

    <p>Supplying oxygenated blood to hepatocytes</p> Signup and view all the answers

    What is the characteristic of the mucosa of the reticulum?

    <p>Non-glandular keratinized stratified squamous mucosa</p> Signup and view all the answers

    What is the primary function of the perisinusoidal space?

    <p>To facilitate exchange between blood and hepatocytes</p> Signup and view all the answers

    What is the location of the central vein in the liver?

    <p>At the center of hepatic lobules</p> Signup and view all the answers

    What type of epithelium lines the bile ducts?

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

    Which of the following is NOT a function of the gallbladder?

    <p>Producing bile</p> Signup and view all the answers

    What is the type of epithelium found in the rumen of the ruminant stomach?

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

    What is the function of the pancreatic polypeptide?

    <p>To regulate pancreatic secretions</p> Signup and view all the answers

    Which of the following enzymes is NOT produced by the exocrine pancreas?

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

    What is the characteristic of the connective tissue in the pancreas?

    <p>Thin connective tissue capsule with trabeculae and VANs</p> Signup and view all the answers

    What is the function of the lacteal in the digestive system?

    <p>Blind-ended lymphatic vessels in the intestinal villi</p> Signup and view all the answers

    What is the characteristic of the mucosa of the reticulum?

    <p>Non-glandular and keratinized</p> Signup and view all the answers

    What is the location of the anal sacs in the digestive system?

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

    What is the main function of the rugae in the glandular stomach?

    <p>To increase the surface area of the stomach</p> Signup and view all the answers

    Which type of teeth do ruminants have?

    <p>Hypsodont teeth</p> Signup and view all the answers

    What is the function of the muscularis layer in the stomach?

    <p>To mix and churn food</p> Signup and view all the answers

    Which layer of the esophagus contains mucous glands?

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

    What is the function of the chief cells in the stomach?

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

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

    <p>To denote entrances to the tubular-shaped gastric glands</p> Signup and view all the answers

    What is the function of the adventitia layer in the esophagus?

    <p>To connect the esophagus to surrounding tissues</p> Signup and view all the answers

    What is the primary function of the Brunner's glands in the duodenum?

    <p>Produce alkaline mucus to protect from acidic chyme</p> Signup and view all the answers

    What type of epithelium is found in the rectum?

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

    What type of epithelium lines the bile ducts in the liver?

    <p>Cuboidal epithelium</p> Signup and view all the answers

    What is the function of the ileum in the small intestine?

    <p>House Peyer's patches of the lymphatic system</p> Signup and view all the answers

    What type of epithelium is found in the anus?

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

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

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

    What is the function of the rumenal papillae?

    <p>To absorb volatile fatty acids</p> Signup and view all the answers

    What is the percentage of the pancreas that is endocrine?

    <p>5%</p> Signup and view all the answers

    What is the function of the central vein in the liver?

    <p>To receive blood mixed in the liver sinusoids and return it to circulation</p> Signup and view all the answers

    What is the characteristic of the connective tissue in the pancreas?

    <p>Thin and delicate</p> Signup and view all the answers

    What is the function of the pancreatic polypeptide?

    <p>To regulate pancreatic secretions</p> Signup and view all the answers

    What tissues are endoderm derived?

    <p>Epithelium, parenchymatous organs (e.g.liver and pancreas) and associated glands.</p> Signup and view all the answers

    What type of lining epithelium is noted from the lips to the nonglandular stomach?

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

    What type of lining epithelium lines the glandular stomach and intestine?

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

    Which of the following are components that form the oral cavity?

    <p>Lips, cheeks, tongue, pharynx palate</p> Signup and view all the answers

    Match the following epithelium to its appropriate cavity/organ.

    <p>Oral cavity = Stratified squamous epithelium Tongue = Stratified squamous epithelium, keratinized on dorsal side Esophagus = Non-keratinized or keratinized stratified squamous epithelium Glandular stomach = Simple columnar</p> Signup and view all the answers

    Which of the following are the four tissues that make up the periodontium?

    <p>Gingivae, periodontal ligament, cementum , alveolar bone</p> Signup and view all the answers

    Which gland is predominantly mucous, but is still a mixed gland?

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

    Study Notes

    Microvilli and Cellular Functions

    • Microvilli are microscopic cellular membrane protrusions that increase surface area for diffusion and minimize volume increase
    • Involved in various functions, including absorption, secretion, cellular adhesion, and mechanotransduction

    Digestive System Components

    • Oral Cavity:
      • Mucosa: stratified squamous epithelium (keratinized or non-keratinized)
      • Submucosa
      • Salivary glands and tonsils
    • Salivary Glands:
      • Major glands: parotid (serous), sublingual (mostly mucous), mandibular
      • Stromal components: connective tissues, VANs, and lymph
      • Parenchymal components: secretory units (adenomere), ducts
      • Minor glands: lingual, palatal, labial, buccal, zygomatic (carnivores), molar (cats)
      • Types of secretions: mixed, serous, mucous
    • Tongue:
      • Mucosa: stratified squamous epithelium (keratinized on dorsal side)
      • Dorsal aspect has gustatory and mechanical papillae
      • Muscularis: skeletal muscle in 3 directions (longitudinal, transverse, and vertical)
    • Teeth:
      • Layers:
        • Enamel: covers entire external surface above gumline
        • Cementum: covers entire external surface below gumline
        • Dentin: beneath enamel and cementum
        • Pulp: loose connective tissue and VANs
        • Periodontal ligament
      • Types of teeth:
        • Brachydont: short and cease to grow after eruption
        • Hypsodont: tall and continue to grow after eruption
    • Esophagus:
      • Epithelium: non-keratinized stratified squamous
      • Lamina propria
      • Muscularis mucosa
      • Submucosa: contains mucous glands
      • Muscularis: skeletal or smooth muscle (depending on species)
      • Adventitia
    • Stomach:
      • Gastric pit: indentations in stomach with entrances to tubular-shaped gastric glands
      • Rugae: folds in mucosal layer to increase surface area
      • Glandular stomach:
        • Mucosa: simple columnar with gastric pits
        • Muscularis: inner oblique, middle circular, outer longitudinal
        • Serosa
        • Regions:
          • Cardia region: entrance into stomach with many mucus glands
          • Fundus: proper gastric glands
          • Pylorus region: exit to duodenum with mucus glands and endocrine G cells
    • Small Intestine:
      • Layers:
        • Epithelium: simple columnar (enterocytes and goblets)
        • Lamina propria: creates villi and microvilli
        • Muscularis
      • Function: nutrient absorption and mucus secretion
      • Areas:
        • Duodenum: Brunner's glands in submucosa produce alkaline mucus
        • Jejunum
        • Ileum: Peyer's patches (lymphatic system)
    • Large Intestine:
      • Function: water absorption
      • Simple columnar epithelium
      • NO villi (intestinal crypts present)
    • Rectum:
      • Simple columnar epithelium
      • Functions: stores feces, secretes mucus
    • Anus:
      • Stratified squamous epithelium
    • Liver:
      • Components:
        • Hepatocytes: polygonal epithelial cells (detox, bile synthesis, gluconogenesis, energy storage)
        • Intrahepatic biliary tree: canals and ducts lined by cuboidal epithelium
        • Kupffer cells: phagocytes of liver (remove aged blood cells, pathogens, and toxins)
        • Sinusoid: capillaries with discontinuous basement membrane and epithelium
        • Perisinusoidal space (space of Disse): site of exchange between blood and hepatocytes
        • Central vein: found at center of hepatic lobules, receives blood mixed in liver sinusoids
    • Gallbladder:
      • Concentrating/modifying reservoir for bile that dumps into duodenum via major and minor papillae
      • Horse has NO gall bladder
      • Mucosa:
        • Bile ducts lined by short columnar epithelium
        • Gall bladder lined by tall columnar epithelium
      • Smooth muscle
      • Serosa
    • Pancreas:
      • Stroma:
        • Thin connective tissue capsule, trabeculae with VANs and lymph vessels (pacinian corpuscles)
      • Parenchyma:
        • Exocrine: 95% of parenchyma (serous acinar glands producing zymogen granules)
        • Endocrine: 5% of parenchyma (islet of Langerhans, secretes insulin, glucagon, somatostatin, pancreatic polypeptide)

    Ruminant Stomach

    • Mucosa of ruminant stomach:
      • Non-glandular keratinized stratified squamous containing papillae
      • Largest compartment: absorption of volatile fatty acids, mixing, regurge, eructation, movement of ingesta
    • Rumen:
      • Non-glandular keratinized stratified squamous
      • Function: absorption of volatile fatty acids, mixing, regurge, eructation, movement of ingesta
    • Reticulum:
      • Non-glandular keratinized stratified squamous, honeycombed shape mucosa
      • Function: absorption of volatile fatty acids, mixing, regurge, eructation, movement of ingesta
    • Omasum:
      • Non-glandular keratinized stratified squamous
      • Function: squeezes ingesta, liquifies and moves it to the abomasum
    • Abomasum:
      • Glandular stomach

    Definitions

    • M cell: specialized epithelium that samples antigens from the lumen environment
    • Intestinal crypt: site of stem cell regeneration
    • Absorption: movement of nutrients, water, and electrolytes from lumen into blood
    • Goblet cell: type of intestinal mucosal epithelial cell
    • Lacteal: blind-ended lymphatic vessels in intestinal villi
    • Submucosal gland: secretes mucus to facilitate movement of particles along tubes
    • Myenteric plexus: major nerve supply to GI tract, controls GI tract motility

    Anorectal Junction and Associated Structures

    • Anorectal junction: site where rectum joins anus
    • Circumanal glands: present in subcutis around anus in dogs
    • Anal sacs: reservoir for anal gland material, keratinized stratified squamous epithelium
    • Anal glands: apocrine secretion in dogs, sebaceous and apocrine in cats

    Ruminant Stomach

    • Function:
      • Absorption of volatile fatty acids
      • Mixing
      • Regurge
      • Eructation
      • Movement of ingesta

    Reticulum

    • Mucosa:
      • Non-glandular keratinized stratified squamous
      • Honeycombed shape
    • Function:
      • Absorption of volatile fatty acids
      • Mixing
      • Regurge
      • Eructation
      • Movement of ingesta

    Omasum

    • Mucosa:
      • Non-glandular keratinized stratified squamous
    • Function:
      • Squeezes ingesta
      • Liquifies and moves it to the abomasum

    Abomasum

    • Mucosa:
      • Glandular stomach
    • Function:
      • Not specified

    Definitions

    • M cell:
      • Specialized epithelium that samples antigens from the lumen environment
    • Absorption:
      • Movement of nutrients, water, and electrolytes from the lumen of the small intestine into the cell, then into the blood
    • Goblet cell:
      • Type of intestinal mucosal epithelial cell
    • Lacteal:
      • Blind-ended lymphatic vessels in the intestinal villi
    • Submucosal gland:
      • Secrete mucus to facilitate the movement of particles along the body's various tubes
    • Myenteric plexus:
      • Major nerve supply to the gastrointestinal tract and controls GI tract motility

    Anorectal Junction

    • Anorectal junction:
      • Line
    • Sphincters:
      • Not specified
    • Circumanal glands:
      • Present in the subcutis around the anus in dogs
    • Anal sacs:
      • Reservoir for anal gland material
      • Keratinized, stratified squamous epithelium
      • Located between the smooth muscle of the internal anal sphincter and the skeletal muscle of the external anal sphincter

    Hepatic Lobule

    • Hepatic acinus:
      • Supplies oxygenated blood to hepatocytes
    • Epithelium:
      • Simple columnar (enterocytes and goblets)
    • Lamina propria:
      • Creates the villi and microvilli
    • Intestinal crypts:
      • At the base of villi (similar to gastric pits)
    • Mucularis:
      • Not specified
    • Function:
      • Nutrient absorption and mucus secretion
    • Areas:
      • Duodenum:
        • Brunner's glands in the submucosa produce alkaline mucus to protect from acidic chyme from the stomach
      • Jejunum:
        • Not specified
      • Ileum:
        • Peyer's patches (lymphatic system)

    Large Intestine

    • Function:
      • Water absorption
    • Epithelium:
      • Simple columnar
    • NO villi:
      • Intestinal crypts present

    Rectum

    • Epithelium:
      • Simple columnar
    • Function:
      • Stores feces and secretes mucus

    Anus

    • Epithelium:
      • Stratified squamous

    Liver

    • Components:
      • Hepatocytes:
        • Polygonal epithelial cells
        • Function:
          • Detox
          • Bile synthesis
          • Gluconogenesis
          • Energy storage
      • Intrahepatic biliary tree:
        • Canals and ducts lined by cuboidal epithelium
        • Bile ducts in the portal triad
        • Oval cells: pluripotent stem cells
      • Kupffer cells:
        • Phagocytes of the liver
        • Located within the blood sinusoids
        • Remove aged blood cells (hemosiderin), pathogens, and some toxins
      • Sinusoid:
        • Capillaries of the liver with discontinuous basement membrane and epithelium
        • Pit cells: resident granular leukocytes
        • Ito cells: Vit.A metabolism, collagen production; contain large rounded lipid vacuoles

    Esophagus

    • Epithelium:
      • Non-keratinized stratified squamous
    • Lamina propria:
      • Not specified
    • Muscularis mucosa:
      • Not specified
    • Submucosa:
      • Contains mucous glands
    • Muscularis:
      • Skeletal or smooth muscle depending on the species
    • Adventitia:
      • Not specified

    Stomach

    • Epithelium:
      • Gastric pit: indentations in the stomach that denote entrances to the tubular-shaped gastric glands
    • Rugae:
      • Folds in the mucosal layer of the glandular stomach to increase surface area
    • Glandular stomach:
      • Mucosa: simple columnar with gastric pits
      • Muscularis:
        • Inner oblique
        • Middle circular
        • Outer longitudinal
      • Serosa:
        • Not specified
      • Regions:
        • Cardia region:
          • Entrance into the stomach
          • Lots of mucus glands
        • Fundus:
          • Magic happens here
          • Proper gastric glands
          • Chief cell:
            • Secrete pepsinogen - stains basophillic
          • Parietal cell:
            • Secrete HCl - stains eosinophillic
          • Endocrine G cell:
            • Produces gastrin - requires special staining
        • Pylorus region:
          • Exit to the duodenum
          • Mucus glands and endocrine G cells

    Gallbladder

    • Function:
      • Concentrating/modifying reservoir for bile that dumps into the duodenum via major and minor papillae
    • Horse:
      • Has no gallbladder
    • Mucosa:
      • Bile ducts lined by short columnar epithelium
      • Gallbladder lined by tall columnar epithelium
    • Smooth muscle:
      • Not specified
    • Serosa:
      • Not specified

    Pancreas

    • Stroma:
      • Thin connective tissue capsule
      • Trabeculae with VANs and lymph vessels (pacinian corpuscles)
    • Parenchyma:
      • Exocrine:
        • 95% of the parenchyma
        • Serous acinar glands producing zymogen granules (eosinophilic)
        • Secrete:
          • Trypsinogen
          • Chymotrypsinogen
          • Lipase
          • Amylase
      • Endocrine:
        • 5% of the parenchyma
        • Islet of Langerhans
        • Secrete:
          • Insulin
          • Glucagon
          • Somatostatin
          • Pancreatic polypeptide

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    This quiz covers the structure and functions of microvilli, and components of the digestive system including the oral cavity and salivary glands.

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