GI Physiology Quiz
33 Questions
2 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which sphincter is responsible for allowing chyme to exit the stomach into the duodenum?

  • Circular sphincter
  • Pyloric sphincter (correct)
  • Lower esophageal sphincter
  • Oblique sphincter

    • Which layer of stomach muscles is responsible for the outermost longitudinal arrangement?

  • Sphincters
  • Oblique
  • Inner (correct)
  • Circular

    • Which substances can be absorbed in the stomach?

  • Vitamins
  • Alcohol (correct)
  • Proteins
  • Carbohydrates

    • What effect does secretin have on the stomach's peristalsis contractions?

    <p>Inhibits contractions</p> Signup and view all the answers

    What stimulates relaxation of the fundus in the stomach during swallowing?

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

    What is the role of cholecystokinin in fat digestion?

    <p>Decreases gastric emptying when fats are present</p> Signup and view all the answers

    Which hormone facilitates the absorption of vitamin B12 in the intestine?

    <p>Intrinsic factor</p> Signup and view all the answers

    What is the role of gastric hydrochloric acid?

    <p>Acts as a bactericide against swallowed organisms</p> Signup and view all the answers

    Which of the following is a function of mucus in the stomach?

    <p>Protects the mucosal barrier</p> Signup and view all the answers

    What causes the inactivation of pepsin in the duodenum?

    <p>Alkaline environment</p> Signup and view all the answers

    What does acetylcholine stimulate in the stomach?

    <p>Enzyme secretion</p> Signup and view all the answers

    What is the primary function of secretin and cholecystokinin in the digestive system?

    <p>Stimulate pancreatic secretions and inhibit gastric secretions</p> Signup and view all the answers

    Which segment of the small intestine absorbs carbs and proteins through active transport into villus capillaries?

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

    What is the primary function of the sphincter of Oddi in the digestive system?

    <p>Regulate bile flow into the small intestine</p> Signup and view all the answers

    Which artery provides the primary blood flow to the small intestine?

    <p>Superior mesenteric artery</p> Signup and view all the answers

    What role do villi play in the small intestine?

    <p>Increase surface area for absorption</p> Signup and view all the answers

    Which layer of the peritoneum lies over the organs in the abdominal and pelvic cavity?

    <p>Visceral peritoneum</p> Signup and view all the answers

    What gives bile its greenish black color and produces the yellow tinge of jaundice?

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

    Which component of bilirubin is lipid soluble and can cross the cell membrane?

    <p>Unconjugated bilirubin</p> Signup and view all the answers

    What is the primary method of bilirubin excretion in the body?

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

    What is the function of trypsin inhibitor in the exocrine pancreas?

    <p>Prevents self-digestion of the pancreas</p> Signup and view all the answers

    Which enzyme in the exocrine pancreas is responsible for digesting carbohydrates?

    <p>Pancreatic a-amylase</p> Signup and view all the answers

    Where does deconjugation of conjugated bilirubin occur in the body?

    <p>Large intestine</p> Signup and view all the answers

    What is the main function of the large intestine?

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

    Which of the following statements about the liver lobules is TRUE?

    <p>Hepatocytes store lipids including vitamin C</p> Signup and view all the answers

    What is the main role of bile salts in digestion?

    <p>Emulsify and absorb fats</p> Signup and view all the answers

    Which reflex inhibits intestinal motility when one segment is over-distended?

    <p>Intestinointestinal reflex</p> Signup and view all the answers

    What are the accessory organs involved in digestion besides the liver and pancreas?

    <p>Gallbladder and exocrine pancreas</p> Signup and view all the answers

    Which cells in the liver remove foreign substances from the blood?

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

    The O'Beirne sphincter controls the movement of wastes from which part of the colon?

    <p>Sigmoid colon</p> Signup and view all the answers

    What is the function of stellate cells in the liver?

    <p>Regulate sinusoidal blood flow and may proliferate into myofibroblasts</p> Signup and view all the answers

    What triggers increased intestinal motility during or immediately after eating?

    <p>Entrance of chyme into the ileum from the stomach</p> Signup and view all the answers

    What is the primary function of the internal anal sphincter?

    <p>Controls movement of wastes from sigmoid colon into rectum</p> Signup and view all the answers

    Study Notes

    Gastric Secretion and Motility

    • Gastric secretion is inhibited by decelerated gastric secretion, secretin, and cholecystokinin.
    • Inhibitory vagal reflexes decrease gastric motility when chyme enters the duodenum.
    • Vagus nerve stimulates gastric secretion and motility.

    Small Intestine

    • The small intestine has three segments: duodenum, jejunum, and ileum.
    • Duodenum:
      • Begins at the pylorus and ends at the Treitz ligament.
      • Receives chyme from the stomach through the pyloric valve.
      • Absorbs vitamins, minerals, fats, and sugars.
      • Presence of chyme stimulates the liver and gallbladder to deliver bile and the pancreas to deliver digestive enzymes and alkaline secretions.
    • Bile and enzymes flow through an opening guarded by the sphincter of Oddi.
    • Bile:
      • Produced by the liver and necessary for fat digestion and absorption.
      • Alkalinity helps neutralize chyme, creating a pH that enables pancreatic enzymes to digest proteins, carbohydrates, and sugars.
    • Jejunum:
      • Absorbs carbohydrates and proteins across the intestinal mucosa by active transport into the villus capillaries.
    • Ileum:
      • Ileocecal valve controls the flow of digested material from the ileum into the large intestine and prevents reflux into the small intestine.
      • Absorbs bile salts, vitamin B12, and chloride.

    Peritoneum and Muscle Layers

    • Peritoneum:
      • Serous membrane surrounding the organs of the abdominal and pelvic cavity.
      • Visceral peritoneum lies over the organs.
      • Parietal peritoneum lines the wall of the abdominal cavity.
      • Inflammation of the peritoneum (peritonitis) occurs with perforation of the intestine or after surgery.
    • Peritoneal cavity:
      • Space between the two layers of the peritoneum.
    • Muscle layers:
      • Outer: longitudinal.
      • Inner: circular.
      • Mucosal folds (plica) within the small intestine slow the passage of food, providing more time for digestion and absorption.

    Digestion and Absorption

    • Carbohydrates:
      • Complex carbohydrates (polysaccharides and oligosaccharides) must be hydrolyzed to their simplest form.
    • Bile:
      • Gives bile a greenish-black color and produces the yellow tinge of jaundice.
      • Unconjugated bilirubin is lipid-soluble and can cross the cell membrane, present in the circulation, bound to plasma protein.
      • Conjugated bilirubin is water-soluble and can be excreted.
    • Urobilinogen:
      • In the ileum and colon, conjugated bilirubin is deconjugated by bacteria and then converted.
      • Gives feces its brown color.

    Exocrine Pancreas

    • Enzymes functions:
      • Trypsinogen, chymotrypsinogen, and procarboxypeptidase: inactivate proteases and are activated by enterokinase.
      • Trypsin inhibitor: prevents the pancreas from eating itself.
      • Pancreatic α-amylase: digests carbohydrates.
      • Pancreatic lipase: digests fats.
      • Pancreatic protease: digests proteins.

    Gastric Emptying

    • Gastric emptying is the movement of gastric contents into the duodenum.
    • Increase gastric emptying: larger volumes of food.
    • Delay gastric emptying: solids, fats, and non-isotonic solutions.

    Fat Digestion

    • Fat digestion stimulates cholecystokinin, which inhibits food intake, gastric motility, and decreases gastric emptying so that fats do not exceed the rate of bile and enzyme secretion.

    Gastric Secretion and Hormones

    • Gastric secretion:
      • Mucus: protective barrier.
      • Acid: hydrochloric acid.
      • Enzymes: pepsinogen.
      • Hormones: gastrin.
      • Intrinsic factor: intestinal absorption of vitamin B12.
      • Gastroferrin: facilitates small intestinal absorption of iron.
    • Gastric hydrochloric acid:
      • Dissolves food fibers.
      • Acts as a bactericide against swallowed organisms.
      • Converts pepsinogen to pepsin.
    • Pepsin:
      • Enzyme that breaks down protein-forming polypeptides in the stomach.
      • Strongest stimulation: acetylcholine.
      • Inactivation: alkaline environment of duodenum.

    Mucus and Ulceration

    • Mucus:
      • Prostaglandins and nitric oxide: protect the mucosal barrier.
      • Aspirin or other non-steroidal anti-inflammatory drugs, Helicobacter pylori, ethanol, regurgitated bile, or ischemia from breaks: cause inflammation and ulceration.

    Stomach and Blood Supply

    • Stomach:
      • Muscle layers: longitudinal, circular, and oblique.
      • Sphincters: lower esophageal sphincter and pyloric sphincter.
      • Blood supply: via branch of celiac artery; drainage via splenic vein and tributaries.
      • Few substances are absorbed in the stomach, such as alcohol, aspirin, and other non-steroidal anti-inflammatory agents.

    Large Intestine

    • Large intestine:
      • Massages fecal mass; absorbs water and electrolytes.
      • Cecum: pouch that receives chyme from the ileum.
      • Appendix: attached to the cecum.
      • Colon: ascending, transverse, descending, and sigmoid.
      • Rectum and anus.
      • Ileocecal valve: admits chyme from the ileum to the cecum.
      • O'Beirne sphincter: controls the movement of wastes from the sigmoid colon into the rectum.
      • Internal anal sphincter: smooth muscle.
      • External anal sphincter: striated skeletal muscle.

    Intestinal Motility

    • Intestinal motility:
      • Peristaltic movements created by the longitudinal muscles propel the chyme along the intestinal tract.
      • Contractions of the circular muscles, called segmentation, mix the chyme and promote digestion.
      • Ileogastric reflex inhibits gastric motility when the ileum is distended.
      • The intestinointestinal reflex inhibits intestinal motility when one intestinal segment is overdistended.
      • Gastroileal reflex increases intestinal motility when gastric motility increases.

    Liver Functions

    • Liver:
      • Produces bile, with salts necessary for fat digestion and absorption.
      • Bile is stored in the gallbladder in between meals.
      • Exocrine pancreas produces enzymes needed for complete digestion of carbohydrates, proteins, and fats.
      • Also produces an alkaline fluid that neutralizes chyme and produces duodenal pH necessary for enzymatic function.
    • Liver lobules:
      • Consist of plates of hepatocytes, which are the functional cells of the liver.
      • Hepatocytes synthesize 700-1200mL of bile per day and secrete it into the bile canaliculi.
      • Bile canaliculi are small channels between the hepatocytes.
      • Can drain bile into the common bile duct and then into the duodenum through an opening called the sphincter of Oddi.
    • Lipocytes:
      • Store lipids, including vitamin A.
    • Kupffer cells:
      • Part of the mononuclear phagocyte system.
      • Phagocytic cells and are central to innate immunity.
    • Stellate cells:
      • Contain retinoids (vitamin A).
      • Are contractile in liver injury.
      • Regulate sinusoidal blood flow.
      • May proliferate into myofibroblasts, participate in liver fibrosis, and remove foreign substances from the blood and trap bacteria.
    • Pit cells:
      • Natural killer cells.
      • Important in tumor defense.

    Liver Functions (continued)

    • Bile secretion:
      • Alkaline, bitter-tasting, yellowish-green fluid that contains bile salts, cholesterol, bilirubin, electrolytes, and water.
      • Bile salts:
        • Conjugated bile acids that are required for the intestinal emulsification and absorption of fats.
        • Formed by hepatocytes and secreted into the bile canaliculi.
        • Primary bile acids are synthesized from cholesterol by the hepatocytes and are required for intestinal emulsification and absorption of fats.
        • Primary acids are then conjugated to form bile salts.
        • Secondary bile acids are the product of bile salts deconjugation by bacteria in the intestinal lumen.
    • Enterohepatic circulation:
      • Recycling of bile salts.
      • Also called choleresis.
      • Choleretic agent: substance that stimulates the liver to secrete bile.
        • Strong stimulus: high concentration of bile salts.
        • Other choleretic agents: secretin, cholecystokinin, vagal stimulation.
    • Vascular and hematologic functions:
      • Stores blood.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    GI Physiology PDF

    Description

    This quiz covers the layers of stomach muscles (longitudinal, circular, oblique), the role of sphincters (lower esophageal, pyloric), blood supply, substances absorption, and gastric motility. Test your knowledge on stomach anatomy!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser