Chapter 25 | GIT Function & Regulation
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Questions and Answers

What accompanies the secretion of protons in the gastrointestinal system?

  • Release of sodium ions
  • Release of potassium ions
  • Release of chloride ions
  • Release of bicarbonate ions (correct)

    • What disrupts the barrier that prevents autodigestion of the mucosa by gastric secretions?

  • Infection with Helicobacter pylori (correct)
  • Increased mucus production
  • Reduction in acid secretion
  • Elevated bicarbonate secretion

    • Which of the following drugs can lead to gastric and duodenal ulceration?

  • Antidepressants
  • Antihistamines
  • Antibiotics
  • Aspirin (correct)

    • What is a primary cause of ulceration in the Zollinger-Ellison syndrome?

    <p>Hypersecretion of acid</p> Signup and view all the answers

    Where are most gastrinomas found in patients with Zollinger-Ellison syndrome?

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

    What is commonly used to combat pain and treat arthritis, but can contribute to ulceration?

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

    What is the purpose of releasing trypsin as an inactive precursor?

    <p>To prevent digestion of the pancreas</p> Signup and view all the answers

    Why does the pancreas secrete a trypsin inhibitor?

    <p>To prevent the activation of trypsin</p> Signup and view all the answers

    What is the primary control mechanism for the secretion of pancreatic juice?

    <p>Hormonal control</p> Signup and view all the answers

    Why are bile acids important in the digestion and absorption of fats?

    <p>To facilitate fat digestion and absorption</p> Signup and view all the answers

    What is the function of bile in the body?

    <p>To dispose of cholesterol</p> Signup and view all the answers

    What gives bile its golden yellow color?

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

    What is the role of Substance P in the gastrointestinal tract?

    <p>Increasing the motility of the small intestine</p> Signup and view all the answers

    Where are the two major nerve fiber networks intrinsic to the gastrointestinal tract located?

    <p>Between the outer longitudinal and middle circular muscle layers</p> Signup and view all the answers

    How many sensory neurons, interneurons, and motor neurons are found in the human gastrointestinal system?

    <p>More than in the spinal cord</p> Signup and view all the answers

    What is the principal physiological action of gastrin?

    <p>Stimulation of gastric acid and pepsin secretion</p> Signup and view all the answers

    What is the enteric nervous system sometimes referred to, and why?

    <p>The little brain for its size</p> Signup and view all the answers

    How is gastrin secretion affected by the presence of protein digestion products in the stomach?

    <p>Stimulates gastrin secretion</p> Signup and view all the answers

    How does Substance P affect growth hormone secretion?

    <p>Indirectly affects it through receptors in the pituitary</p> Signup and view all the answers

    Which cells in the gastric mucosa produce gastrin?

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

    What are the functions of the myenteric plexus (Auerbach plexus) within the gastrointestinal tract?

    <p>Controls muscle movements between certain layers</p> Signup and view all the answers

    How does acid in the antrum affect gastrin secretion?

    <p>Inhibits gastrin secretion</p> Signup and view all the answers

    What are hormones or paracrines in the gastrointestinal system primarily secreted by?

    <p>Nerve cells and gland cells</p> Signup and view all the answers

    How do gastrointestinal hormones like gastrin primarily act in the body?

    <p>Paracrine and endocrine fashion</p> Signup and view all the answers

    Which plexus is primarily involved in the control of intestinal secretion?

    <p>Submucous plexus</p> Signup and view all the answers

    Which neurotransmitter is NOT mentioned as part of the gastrointestinal system?

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

    The gastrointestinal system evolved to permit controlled nutrient uptake in __________ organisms.

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

    Which component of bile is essential in the chemical alteration of meal components for absorption?

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

    What is the primary function of the myenteric plexus?

    <p>Motor control of smooth muscle layers</p> Signup and view all the answers

    Which gas is mentioned as part of the neurotransmitters in the gastrointestinal system?

    <p>Nitric oxide</p> Signup and view all the answers

    What is the main action of gastrin in the gastrointestinal system?

    <p>Stimulating pancreatic enzyme secretion</p> Signup and view all the answers

    Which stimuli inhibit gastrin secretion in the gastrointestinal system?

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

    Where are endocrine cells secreting cholecystokinin (CCK) found?

    <p>In the upper small intestine</p> Signup and view all the answers

    What is the primary function of CCK in the gastrointestinal system?

    <p>Promoting bile flow</p> Signup and view all the answers

    Which neurotransmitter is involved in increasing gastrin secretion through vagal discharge?

    <p>Cholecystokinin releasing peptide (GRP)</p> Signup and view all the answers

    What is the effect of luminal peptides and amino acids on gastrin secretion?

    <p>Increase gastrin secretion</p> Signup and view all the answers

    What is the primary function of bile acids in the digestive process?

    <p>Facilitate the absorption of vitamins</p> Signup and view all the answers

    Which of the following is NOT a modality for gastrointestinal regulation mentioned in the text?

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

    How does endocrine regulation differ from paracrine regulation in gastrointestinal function?

    <p>Endocrine signals target distant organs, while paracrine signals act locally</p> Signup and view all the answers

    Which component of the gastrointestinal system has extensive neural connections to both the central nervous system and an autonomous nervous system?

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

    What is the main function of the enteric nervous system within the gastrointestinal tract?

    <p>Coordinate sensory and secretomotor neurons</p> Signup and view all the answers

    How do gastrointestinal hormones differ from paracrines in their mode of action?

    <p>Hormones act via the bloodstream, while paracrines act locally</p> Signup and view all the answers

    What is the main function of Substance P in the gastrointestinal tract?

    <p>Increasing motility of the small intestine</p> Signup and view all the answers

    Which nervous system is sometimes referred to as the 'little brain' due to its autonomous function in regulating gastrointestinal activities?

    <p>Enteric Nervous System</p> Signup and view all the answers

    How many major networks of nerve fibers are intrinsic to the gastrointestinal tract?

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

    What is the collective term for the approximately 100 million neurons found in the gastrointestinal system?

    <p>Enteric Nervous System</p> Signup and view all the answers

    What stimulates parietal and chief cells in the stomach?

    <p>Acetylcholine released from enteric nerve endings</p> Signup and view all the answers

    During which phase is gastric secretion predominantly activated by vagal input?

    <p>Cephalic phase</p> Signup and view all the answers

    What serves as a feedback inhibitory signal to shut off gastric secretion?

    <p>Release of somatostatin</p> Signup and view all the answers

    What is the key mechanism that terminates gastric secretion after a meal moves from the stomach to the small intestine?

    <p>Presence of meal constituents</p> Signup and view all the answers

    What is the primary function of mitochondria in gastric parietal cells?

    <p>Supplying energy for the proton pump</p> Signup and view all the answers

    What plays a crucial role in buffering gastric acidity and terminating gastric secretion post-meal?

    <p>Presence of meal constituents</p> Signup and view all the answers

    What is the primary function of gastrin in the gastrointestinal system?

    <p>Stimulating growth of the stomach mucosa</p> Signup and view all the answers

    How is gastrin secretion affected by the presence of amino acids in the stomach?

    <p>It activates G cells to secrete more gastrin</p> Signup and view all the answers

    What is the effect of acid in the antrum on gastrin secretion?

    <p>Inhibits gastrin secretion</p> Signup and view all the answers

    Which factors affect the secretion of gastrointestinal hormones like gastrin?

    <p>Rate of discharge of the vagus nerves</p> Signup and view all the answers

    What is the role of somatostatin in relation to gastrin?

    <p>Inhibits gastric acid and pepsin secretion</p> Signup and view all the answers

    How do hormones and paracrines function within the gastrointestinal system?

    <p>By acting in a paracrine manner and sometimes entering circulation</p> Signup and view all the answers

    What is the primary function of the myenteric plexus within the gastrointestinal tract?

    <p>Primarily involved in motor control</p> Signup and view all the answers

    Which neurotransmitter is NOT mentioned as part of the gastrointestinal system?

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

    What is the main role of the submucous plexus in the gastrointestinal system?

    <p>Innervates glandular epithelium and controls intestinal secretion</p> Signup and view all the answers

    What activity describes the function of digestive secretions in the gastrointestinal system?

    <p>Breaking down macromolecules for absorption</p> Signup and view all the answers

    Which neurotransmitter contributes to gastrointestinal regulation by affecting smooth muscle contractions?

    <p>Nitric oxide (NO)</p> Signup and view all the answers

    How are some peptides released by the gastrointestinal system different from others?

    <p>Serving as hormones</p> Signup and view all the answers

    What is the evolutionary advantage of the gastrointestinal system being functionally continuous with the outside environment?

    <p>Enhanced nutrient absorption</p> Signup and view all the answers

    Which component is NOT found in digestive secretions that chemically alter meal components?

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

    How do paracrine factors differ from hormones in their role within the gastrointestinal system?

    <p>Act on nearby cells</p> Signup and view all the answers

    Which gas molecule serves as a neurotransmitter involved in gastrointestinal regulation?

    <p>Nitric oxide (NO)</p> Signup and view all the answers

    What is the primary purpose of digestive secretions in relation to meal components?

    <p>Chemically alter components for absorption</p> Signup and view all the answers

    How do neurotransmitters like serotonin differ from ATP in their influence on gastrointestinal activities?

    <p>Control muscle contraction differently</p> Signup and view all the answers

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