Gastrointestinal System Overview
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Questions and Answers

What is the length of the GI tract in its normal contractile state?

  • 4.5 m long (correct)
  • 3 m long
  • 6 m long
  • 9 m long

    • Which of the following is NOT an accessory digestive organ?

  • Exocrine pancreas
  • Salivary glands
  • Kidney (correct)
  • Appendix

    • What is the function of motility in the GIT?

  • Absorption of nutrients
  • Regulation of gut endocrine system
  • Secretion of digestive enzymes
  • Movement of food throughout the GIT (correct)

    • Which part of the large intestine is responsible for storing and eliminating waste?

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

    What is the term for the abnormal out-pouching of the LI?

    <p>Diverticular disease</p> Signup and view all the answers

    What is the term for the sensation of difficulty swallowing?

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

    Which part of the small intestine is the shortest?

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

    What is the term for the passage of blood through the digestive tract?

    <p>GI bleeding</p> Signup and view all the answers

    What type of receptors in the digestive tract wall detect the stretch or tension in the gut wall?

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

    Which of the following cells in the stomach produces pepsinogen?

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

    What is the primary function of the parasympathetic nerve in salivary secretion?

    <p>Produces a prompt and abundant flow of watery saliva</p> Signup and view all the answers

    Which of the following is NOT a function of the gut endocrine system?

    <p>Digests carbohydrates</p> Signup and view all the answers

    What is the primary substrate for salivary amylase?

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

    Which of the following hormones is NOT produced by the gut endocrine system?

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

    What is the primary function of the osmoreceptors in the digestive tract wall?

    <p>Detecting osmotic composition of the luminal fluid</p> Signup and view all the answers

    What is the primary function of lingual lipase?

    <p>Hydrolyzing complex lipids into fatty acids and glycerol</p> Signup and view all the answers

    What is the main function of bile salts in the small intestine?

    <p>To emulsify large fat globules for attack by pancreatic lipase</p> Signup and view all the answers

    What is the primary function of the mucosa layer in the GIT wall?

    <p>To absorb digestive nutrients and secrete digestive juices</p> Signup and view all the answers

    What is the main component of the lamina propria?

    <p>Connective tissue</p> Signup and view all the answers

    What is the function of the muscularis mucosa layer?

    <p>To provide mechanical support to the mucosa</p> Signup and view all the answers

    What is the main function of the submucosa layer?

    <p>To facilitate distensibility and elasticity of the GIT</p> Signup and view all the answers

    What is the main component of the muscularis externa layer?

    <p>Smooth muscle cells</p> Signup and view all the answers

    What is the function of the myenteric plexus?

    <p>To produce smooth muscle contractions</p> Signup and view all the answers

    What is the location of the pacemaker cells known as the interstitial cells of Cajal?

    <p>Between the two muscle layers of the muscularis externa</p> Signup and view all the answers

    What is the sequence of events by which gastrin causes stimulation of acid secretion?

    <p>Position 1, 2, 3, 4</p> Signup and view all the answers

    Would histamine released by gastrin cause responses in other organs such as skin and airways smooth muscle?

    <p>No, it would not cause responses in other organs</p> Signup and view all the answers

    Which of the following would be more efficient at blocking excessive gastric acid secretion?

    <p>Proton Pump Inhibitors (PPIs)</p> Signup and view all the answers

    What events occur in the cell during stimulation of the vagus nerve?

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

    How does caffeine affect gastric acid secretion?

    <p>It increases gastric acid secretion</p> Signup and view all the answers

    What is the role of histamine in gastric acid secretion?

    <p>It stimulates the release of acid from parietal cells</p> Signup and view all the answers

    What is the effect of gastrin on gastric acid secretion?

    <p>It stimulates the release of acid from parietal cells</p> Signup and view all the answers

    Which of the following is a stimulus for gastric acid secretion?

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

    What is the primary function of the serosa in the digestive system?

    <p>To secrete watery, slippery fluid to prevent friction</p> Signup and view all the answers

    What is the term for the spontaneous, rhythmic cycles of depolarization and repolarization in the autonomic smooth muscle system?

    <p>Basic electrical rhythm (BER)</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system in the digestive system?

    <p>To coordinate activity among different regions of the digestive system</p> Signup and view all the answers

    What is the origin of the parasympathetic innervation in the digestive system?

    <p>Medulla and sacral spinal cord</p> Signup and view all the answers

    What is the consequence of damage to the parasympathetic innervation in the digestive system?

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

    What is the role of the interstitial cells of Cajal in the autonomic smooth muscle system?

    <p>To generate slow-wave potentials</p> Signup and view all the answers

    What is the result of an increase in cytosolic Ca2+ concentration in the autonomic smooth muscle system?

    <p>Greater cross-bridge activity</p> Signup and view all the answers

    What is the term for the self-induced electrical activity in the autonomic smooth muscle system?

    <p>Basic electrical rhythm (BER)</p> Signup and view all the answers

    What is the primary function of the serosa in the digestive system?

    <p>To secrete watery, slippery fluid to prevent friction between the digestive organs and surrounding viscera</p> Signup and view all the answers

    What is the term for the spontaneous, rhythmic cycles of depolarization and repolarization in the autonomic smooth muscle system?

    <p>Basic electrical rhythm</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system in the digestive system?

    <p>To coordinate activity among different regions of the digestive system</p> Signup and view all the answers

    Where do the parasympathetic nerves that control the digestive system arise from?

    <p>Medulla and sacral spinal cord</p> Signup and view all the answers

    What is the result of an increase in cytosolic Ca2+ concentration in the autonomic smooth muscle system?

    <p>Greater cross-bridge activity and stronger contraction</p> Signup and view all the answers

    What is the role of the interstitial cells of Cajal in the autonomic smooth muscle system?

    <p>To generate slow-wave potentials that propagate via gap junctions</p> Signup and view all the answers

    What is the sequence of events by which gastrin causes stimulation of acid secretion?

    <p>Gastrin stimulates the release of histamine, which binds to receptors on parietal cells, leading to the release of acid.</p> Signup and view all the answers

    What is the consequence of damage to the parasympathetic innervation in the digestive system?

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

    What is the term for the self-induced electrical activity in the autonomic smooth muscle system?

    <p>Basic electrical rhythm</p> Signup and view all the answers

    Would histamine released by gastrin cause responses in other organs such as skin and airways smooth muscle?

    <p>Yes, histamine has a systemic effect.</p> Signup and view all the answers

    Which of the following would be more efficient at blocking excessive gastric acid secretion?

    <p>Proton Pump Inhibitors (PPIs)</p> Signup and view all the answers

    What events occur in the cell during stimulation of the vagus nerve?

    <p>Release of gastrin and stimulation of acid secretion</p> Signup and view all the answers

    How does caffeine affect gastric acid secretion?

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

    What is the role of histamine in gastric acid secretion?

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

    What is the effect of gastrin on gastric acid secretion?

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

    Which of the following is a stimulus for gastric acid secretion?

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

    What is the primary function of ECL cells in the stomach?

    <p>Stimulate parietal cells and chief cells</p> Signup and view all the answers

    What is the primary function of the enteric nervous system in the GI tract?

    <p>To control the digestion and absorption of nutrients</p> Signup and view all the answers

    What is the primary function of bile salts in the small intestine?

    <p>Emulsifying large fat globules for attack by pancreatic lipase</p> Signup and view all the answers

    Which of the following is a common symptom of gastrointestinal problems?

    <p>Abdominal pain</p> Signup and view all the answers

    What type of receptors in the digestive tract wall detect the chemical composition of luminal fluid?

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

    Which layer of the GIT wall contains the gut-associated lymphoid tissue (GALT)?

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

    What is the primary function of the myenteric plexus?

    <p>Coordinating the mixing and propulsion of food through the GIT</p> Signup and view all the answers

    What is the primary function of lingual lipase?

    <p>Hydrolysis of complex lipids into fatty acids and glycerol</p> Signup and view all the answers

    What is the main function of the salivary glands in the digestive system?

    <p>To produce saliva that lubricates food and breaks down carbohydrates</p> Signup and view all the answers

    Which layer of the GIT wall provides distensibility and elasticity?

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

    Which organ is responsible for producing bile that breaks down fats into fatty acids and glycerol?

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

    What is the primary function of the gut endocrine system?

    <p>Stimulation of digestive enzyme secretion</p> Signup and view all the answers

    What is the function of the interstitial cells of Cajal in the autonomic smooth muscle system?

    <p>Generating the spontaneous, rhythmic cycles of depolarization and repolarization</p> Signup and view all the answers

    What type of saliva is produced by the sympathetic nervous system?

    <p>Thick saliva rich in mucus</p> Signup and view all the answers

    What is the term for the abnormal out-pouching of the large intestine?

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

    What is the primary function of salivary amylase?

    <p>Breakdown of starch into maltose and α-limit dextrins</p> Signup and view all the answers

    Which part of the nervous system regulates the autonomic functions of the GI tract?

    <p>Autonomic nervous system</p> Signup and view all the answers

    What is the primary component of the muscularis externa?

    <p>Smooth muscle cells</p> Signup and view all the answers

    What is the main function of the stomach in the digestive system?

    <p>To mix food with digestive enzymes and acids</p> Signup and view all the answers

    What is the function of the mucosa layer in the GIT wall?

    <p>Protecting the GIT wall from the luminal contents</p> Signup and view all the answers

    What type of receptors in the digestive tract wall detect the osmotic composition of the luminal fluid?

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

    What is the primary function of the parasympathetic nervous system in salivary secretion?

    <p>Production of a prompt and abundant flow of watery saliva</p> Signup and view all the answers

    What is the primary function of the serosa in the digestive system?

    <p>Protecting the outer surface of the GIT from the surrounding tissues</p> Signup and view all the answers

    Which of the following is NOT a function of the gut endocrine system?

    <p>Regulating blood pressure</p> Signup and view all the answers

    What is the primary function of the gut endocrine system?

    <p>To regulate digestion and absorption of nutrients</p> Signup and view all the answers

    What is the term for the abnormal out-pouching of the large intestine?

    <p>Diverticular disease</p> Signup and view all the answers

    Which of the following is a systemic disorder with GI origin?

    <p>Vitamin malabsorption</p> Signup and view all the answers

    What is the primary function of the enteric nervous system?

    <p>To control the smooth muscle contraction in the gut wall</p> Signup and view all the answers

    What is the term for the sensation of difficulty swallowing?

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

    Which part of the digestive system is responsible for the mechanical breakdown of food?

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

    What is the term for the passage of food through the digestive system?

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

    What is the primary function of the autonomic nervous system in the digestive system?

    <p>To control the smooth muscle contraction in the gut wall</p> Signup and view all the answers

    What is the function of amylase in the digestive system?

    <p>Hydrolyses polysaccharides to disaccharides and α-limit dextrins</p> Signup and view all the answers

    Which enzyme is responsible for hydrolyzing protein to peptide fragments in the stomach?

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

    Where does the enzyme trypsinogen act?

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

    What is the function of disaccharidases in the small intestine?

    <p>Hydrolyses disaccharides to monosaccharides</p> Signup and view all the answers

    What is the site of action of the enzyme pepsin?

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

    What is the function of the exocrine pancreas in the digestive system?

    <p>Secretes digestive enzymes into the small intestine</p> Signup and view all the answers

    What is the site of action of the enzymes trypsin, chymotrypsin, and carboxypeptidase?

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

    Which enzymes are responsible for breaking down polysaccharides to disaccharides and α-limit dextrins?

    <p>Amylase and disaccharidases</p> Signup and view all the answers

    What is the primary function of the pharynx and oesophagus?

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

    What is the condition characterized by a lack of neuronal input into swallowing and peristalsis function?

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

    What is the function of the gastroesophageal sphincter?

    <p>To prevent reflux of gastric contents</p> Signup and view all the answers

    What is the main function of the myenteric plexus?

    <p>Control of motor activity and peristalsis</p> Signup and view all the answers

    What is the primary function of mucus in the oesophagus?

    <p>To protect the oesophagus from damage</p> Signup and view all the answers

    What type of nervous system integrates the functions of the GIT?

    <p>Autonomic nervous system (ANS)</p> Signup and view all the answers

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

    <p>To act as a mixing chamber and holding reservoir</p> Signup and view all the answers

    What is the location of the submucosal plexus?

    <p>Submucosal layer</p> Signup and view all the answers

    What enzyme is responsible for hydrolyzing polysaccharides to disaccharides and α-limit dextrins in the mouth and stomach?

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

    What is the function of the enteric nervous system?

    <p>Control of digestive functions</p> Signup and view all the answers

    What is the transit time of food through the oesophagus?

    <p>6-10 seconds</p> Signup and view all the answers

    What is the result of stimulation of the myenteric plexus?

    <p>Increased tone of the gut wall</p> Signup and view all the answers

    What is the consequence of achalasia?

    <p>Difficulty in swallowing</p> Signup and view all the answers

    What is the function of the parasympathetic nerves in the GIT?

    <p>Stimulation of gut motility and secretion</p> Signup and view all the answers

    What is the role of the vagal nuclei in the regulation of GIT functions?

    <p>Integration of parasympathetic and sympathetic inputs</p> Signup and view all the answers

    What is the main function of the autonomic nervous system in the digestive system?

    <p>Integration of digestive functions</p> Signup and view all the answers

    What percentage of peptic ulcers are caused by Helicobacter pylori?

    <p>More than 80%</p> Signup and view all the answers

    What is the function of urease produced by Helicobacter pylori?

    <p>Breaks down urea into ammonia and CO2</p> Signup and view all the answers

    What is the effect of Helicobacter pylori on the gastric mucosal barrier?

    <p>Weakens the barrier by disrupting tight junctions</p> Signup and view all the answers

    What is the function of histamine in gastric acid secretion?

    <p>Potentiates the acid-promoting actions of Ach and gastrin</p> Signup and view all the answers

    What is the function of proton pump inhibitors in treating peptic ulcers?

    <p>Block the pump that transports H+ into the stomach lumen</p> Signup and view all the answers

    What is the effect of alcohol and NSAIDs on the gastric mucosal barrier?

    <p>Weaken the barrier</p> Signup and view all the answers

    What is the function of H-2 histamine receptor blockers in treating peptic ulcers?

    <p>Block the action of histamine on acid secretion</p> Signup and view all the answers

    What is the role of antibiotics in treating peptic ulcers caused by Helicobacter pylori?

    <p>Kill Helicobacter pylori</p> Signup and view all the answers

    What is the primary function of bile salts in the small intestine?

    <p>Emulsify large fat globules for attack by pancreatic lipase</p> Signup and view all the answers

    What is the main component of the mucosa layer in the GIT wall?

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

    What is the primary function of the muscularis externa layer?

    <p>Contraction produces the propulsive and mixing movement</p> Signup and view all the answers

    What is the role of the submucosal plexus nerve network?

    <p>Regulation of smooth muscle contraction</p> Signup and view all the answers

    What is the location of the pacemaker cells known as the interstitial cells of Cajal?

    <p>Muscularis externa layer</p> Signup and view all the answers

    What is the primary function of the myenteric plexus?

    <p>Regulation of smooth muscle contraction</p> Signup and view all the answers

    What is the primary function of the lamina propria?

    <p>Providing distensibility and elasticity</p> Signup and view all the answers

    What is the primary function of the serosa layer?

    <p>Protection and support of the GIT</p> Signup and view all the answers

    What is the site of action of trypsinogen?

    <p>Small intestine lumen</p> Signup and view all the answers

    What is the function of aminopeptidases?

    <p>Hydrolyse peptide fragments into amino acids and small peptides</p> Signup and view all the answers

    What is the site of action of lipase?

    <p>Small intestine lumen</p> Signup and view all the answers

    What is the result of trypsinogen activation?

    <p>Trypsinogen is converted to trypsin</p> Signup and view all the answers

    What is the site of action of procarboxypeptidase?

    <p>Small intestine lumen</p> Signup and view all the answers

    What is the function of chymotrypsinogen?

    <p>Attack different peptide fragments</p> Signup and view all the answers

    What is the site of production of lipase?

    <p>Exocrine pancreas</p> Signup and view all the answers

    What is the result of lipase action?

    <p>Triglycerides are converted to monoglycerides and fatty acids</p> Signup and view all the answers

    What is the primary function of segmentation in the small intestine?

    <p>To mix and absorb digested nutrients</p> Signup and view all the answers

    Which of the following statements is TRUE about the innervation of the external anal sphincter?

    <p>It is innervated by skeletal muscle fibers</p> Signup and view all the answers

    What is the primary function of the circular muscle in the small intestine?

    <p>To regulate the contraction and relaxation of adjacent smooth muscle</p> Signup and view all the answers

    What is the term for the sequential contraction and relaxation of adjacent smooth muscle in the gut?

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

    What is the primary function of the pancreatic amylase?

    <p>To break down carbohydrates into monosaccharides</p> Signup and view all the answers

    What is the term for the sensation of difficulty swallowing?

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

    What is the primary function of the gastrin released by G cells in the pyloric gland area?

    <p>To stimulate the release of gastric acid</p> Signup and view all the answers

    What is the term for the reabsorption of digestive secretions back into the blood?

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

    What is the primary function of the serosa in the digestive system?

    <p>To prevent friction between the digestive organs and surrounding viscera</p> Signup and view all the answers

    Which of the following is responsible for generating slow-wave potentials that propagate via gap junctions?

    <p>Interstitial cells of Cajal</p> Signup and view all the answers

    What is the result of an increase in cytosolic Ca2+ concentration in the autonomic smooth muscle system?

    <p>Stronger contraction</p> Signup and view all the answers

    What is the term for the spontaneous, rhythmic cycles of depolarization and repolarization in the autonomic smooth muscle system?

    <p>Basic electrical rhythm (BER)</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system in the digestive system?

    <p>To coordinate activity among different regions of the digestive system</p> Signup and view all the answers

    What is the origin of the parasympathetic innervation in the digestive system?

    <p>Medulla and sacral spinal cord</p> Signup and view all the answers

    What is the consequence of damage to the parasympathetic innervation in the digestive system?

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

    What is the role of the interstitial cells of Cajal in the autonomic smooth muscle system?

    <p>To generate slow-wave potentials</p> Signup and view all the answers

    What is the primary regulator of salivary secretion?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    During swallowing, what prevents food from entering the trachea?

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

    What is the primary function of amylase in saliva?

    <p>Break down carbohydrates</p> Signup and view all the answers

    What is the result of damage to the central nervous system control of swallowing?

    <p>Impaired swallowing reflex</p> Signup and view all the answers

    What is the function of lysozyme in saliva?

    <p>Kill bacteria</p> Signup and view all the answers

    What is the primary function of the pharyngeal stage of swallowing?

    <p>To stimulate the deglutition center in the brain stem</p> Signup and view all the answers

    What is the purpose of the epiglottis during swallowing?

    <p>To separate the trachea from the esophagus</p> Signup and view all the answers

    What is the primary function of mucus in saliva?

    <p>To lubricate food for easy swallowing</p> Signup and view all the answers

    What is the primary neurotransmitter released by the parasympathetic nervous system in the gastrointestinal tract?

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

    In which layers of the gastrointestinal tract wall are the intrinsic (enteric) nerves located?

    <p>Submucosa and between circular and longitudinal muscle layers</p> Signup and view all the answers

    What is the effect of the sympathetic nervous system on the digestive tract?

    <p>Decreases smooth muscle motility and inhibits secretion of digestive enzymes</p> Signup and view all the answers

    What type of neurotransmitter is released by the sympathetic nervous system in the gastrointestinal tract?

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

    Which of the following is NOT a component of the gut endocrine system?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    What is the function of the myenteric plexus?

    <p>Control of motility</p> Signup and view all the answers

    What is the origin of the sympathetic innervation in the digestive system?

    <p>Spinal cord (T5-L2)</p> Signup and view all the answers

    What is the consequence of damage to the parasympathetic innervation in the digestive system?

    <p>Decreased motility and secretion</p> Signup and view all the answers

    Where is trypsinogen activated by enteropeptidase?

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

    What is the function of aminopeptidases in the small intestine?

    <p>Hydrolyse peptide fragments into amino acids</p> Signup and view all the answers

    What is the product of lipase action on triglycerides?

    <p>Monoglycerides and free fatty acids</p> Signup and view all the answers

    In which part of the small intestine are aminopeptidases found?

    <p>Brush border</p> Signup and view all the answers

    What is the site of action of procarboxypeptidase?

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

    What is the function of lipase in the small intestine?

    <p>Hydrolyse triglycerides into fatty acids</p> Signup and view all the answers

    What is the product of aminopeptidase action on peptide fragments?

    <p>Amino acids and small peptides</p> Signup and view all the answers

    In which organ is trypsinogen produced?

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

    What is the primary function of the gut endocrine system in the digestive process?

    <p>To modulate the activity of exocrine and endocrine gland cells</p> Signup and view all the answers

    Which type of receptor in the gut wall is responsible for detecting the osmotic composition of the luminal fluid?

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

    What is the primary function of the vagus nerve in salivary secretion?

    <p>To produce a prompt and abundant flow of watery saliva</p> Signup and view all the answers

    What is the primary substrate for lingual lipase in the mouth?

    <p>Complex lipids</p> Signup and view all the answers

    Which type of cell in the stomach produces pepsinogen?

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

    What is the effect of gastrin on parietal cells in the stomach?

    <p>Stimulates the secretion of HCl and intrinsic factors</p> Signup and view all the answers

    Which type of receptor in the gut wall is responsible for detecting the stretch or tension in the gut wall?

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

    What is the primary function of the enterochromaffin-like (ECL) cells in the stomach?

    <p>To stimulate the secretion of HCl and intrinsic factors</p> Signup and view all the answers

    What is the sequence of events by which gastrin causes stimulation of acid secretion in the stomach?

    <p>Gastrin binds to receptors on enterochromaffin-like cells, stimulating the release of histamine, which then binds to H2 receptors on parietal cells.</p> Signup and view all the answers

    What would be the effect of blocking H2 receptors on gastric acid secretion?

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

    What is the effect of caffeine on gastric acid secretion?

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

    What is the primary mechanism by which gastrin stimulates acid secretion?

    <p>Stimulating the release of histamine from enterochromaffin-like cells</p> Signup and view all the answers

    What would be the consequence of blocking the vagus nerve on gastric acid secretion?

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

    What is the role of histamine in gastric acid secretion?

    <p>Binds to H2 receptors on parietal cells, stimulating acid secretion</p> Signup and view all the answers

    What is the primary site of action of PPIs in blocking gastric acid secretion?

    <p>Proton pumps on parietal cells</p> Signup and view all the answers

    What is the effect of histamine released by gastrin on other organs?

    <p>Stimulates responses in skin and airways smooth muscle</p> Signup and view all the answers

    What percentage of peptic ulcers are caused by Helicobacter pylori?

    <p>80%</p> Signup and view all the answers

    What is the function of urease in Helicobacter pylori?

    <p>Breaks down urea into ammonia and CO2</p> Signup and view all the answers

    What is the effect of Helicobacter pylori on the gastric mucosal barrier?

    <p>Weakens the barrier</p> Signup and view all the answers

    What is the mechanism of action of proton pump inhibitors in treating peptic ulcers?

    <p>Blocks the pump that transports H+ into the stomach lumen</p> Signup and view all the answers

    What is the role of histamine in gastric acid secretion?

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

    What is the function of the gastric mucosal barrier?

    <p>Protects the stomach from acid and enzymes</p> Signup and view all the answers

    What is the effect of alcohol and NSAIDs on the gastric mucosal barrier?

    <p>Weaken the barrier</p> Signup and view all the answers

    What is the role of antibiotics in treating peptic ulcers?

    <p>Kill Helicobacter pylori</p> Signup and view all the answers

    What is unique about salivary secretion?

    <p>It is the only digestive secretion entirely under neural control.</p> Signup and view all the answers

    What is the function of lysozyme in saliva?

    <p>To kill bacteria.</p> Signup and view all the answers

    What is the main function of the myenteric plexus?

    <p>Control of motor activity of the gut wall</p> Signup and view all the answers

    What happens during the pharyngeal stage of swallowing?

    <p>The bolus stimulates stretch receptors in the oropharynx.</p> Signup and view all the answers

    Why does the uvula elevate during swallowing?

    <p>To prevent food from entering the nasal passageways.</p> Signup and view all the answers

    Which of the following is a function of the submucosal plexus?

    <p>Control of local absorption and secretion</p> Signup and view all the answers

    What is the role of the parasympathetic nerves in the regulation of digestion?

    <p>Stimulation of smooth muscle contraction</p> Signup and view all the answers

    What happens during the oesophageal stage of swallowing?

    <p>The bolus is involuntarily passed through the oesophagus into the stomach.</p> Signup and view all the answers

    What is the term for the self-regulating system of organs that coordinates motor, secretory, digestive, and absorptive functions?

    <p>Gastrointestinal tract</p> Signup and view all the answers

    What is the result of a stroke on the swallowing reflex?

    <p>The swallowing reflex is impaired.</p> Signup and view all the answers

    What is the function of the epiglottis during swallowing?

    <p>To prevent food from entering the trachea.</p> Signup and view all the answers

    What is the location of the myenteric plexus?

    <p>Muscularis externa layer</p> Signup and view all the answers

    What is the function of the enteric nervous system?

    <p>Control of gut motility and secretion</p> Signup and view all the answers

    What is the function of amylase in saliva?

    <p>To begin to digest carbohydrates.</p> Signup and view all the answers

    What is the role of the vagal nuclei in the regulation of digestion?

    <p>Stimulation of parasympathetic nerves</p> Signup and view all the answers

    What is the main function of the autonomic nervous system in the digestive system?

    <p>Regulation of gut motility and secretion</p> Signup and view all the answers

    Where does amylase hydrolyze polysaccharides to?

    <p>disaccharides and α-limit dextrins</p> Signup and view all the answers

    What is the function of pepsin in the stomach?

    <p>Hydrolyze protein to peptide fragments</p> Signup and view all the answers

    Where does trypsinogen get activated in the digestive system?

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

    What is the function of lactase in the small intestine?

    <p>Hydrolyze disaccharides to monosaccharides</p> Signup and view all the answers

    What is the site of action for pepsin?

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

    What is the function of sucrase-isomaltase in the small intestine?

    <p>Hydrolyze disaccharides to monosaccharides</p> Signup and view all the answers

    What is the site of action for maltase?

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

    What is the function of trypsin in the small intestine?

    <p>Hydrolyze proteins to peptide fragments</p> Signup and view all the answers

    What is the primary function of the pharynx and oesophagus?

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

    What is the result of achalasia?

    <p>Difficulty in swallowing (dysphagia)</p> Signup and view all the answers

    What is the function of the gastroesophageal sphincter?

    <p>To prevent reflux of gastric contents</p> Signup and view all the answers

    What is the function of mucus in the oesophagus?

    <p>To provide lubrication and protection</p> Signup and view all the answers

    What is the function of the stomach?

    <p>To act as a mixing chamber and holding reservoir</p> Signup and view all the answers

    What is the site of action of salivary amylase?

    <p>Mouth and body of stomach</p> Signup and view all the answers

    What is the function of the thick muscle layer in the stomach?

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

    What is the result of reflux of gastric contents into the oesophagus?

    <p>Heartburn and irritation of the oesophagus</p> Signup and view all the answers

    What is the main factor that increases HCl secretion during meal digestion?

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

    Which cell type produces histamine in response to gastrin and Ach?

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

    What is the function of somatostatin in the regulation of gastric secretion?

    <p>Inhibits secretion by parietal cells, G cells, and ECL cells</p> Signup and view all the answers

    Which phase of gastric secretion is stimulated by the sight, smell, taste, and thought of food?

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

    What is the function of secretin in the regulation of gastric secretion?

    <p>Reduces gastric secretion</p> Signup and view all the answers

    Which hormone inhibits gastric emptying in response to fat in the duodenum?

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

    What is the function of gastrin in the regulation of gastric secretion?

    <p>Stimulates parietal and chief cells to increase HCl secretion</p> Signup and view all the answers

    Which receptor type in the stomach detects the stretch or tension in the gut wall?

    <p>Stretch receptors</p> Signup and view all the answers

    Study Notes

    Overview of Gastrointestinal System

    • The GI tract is approximately 4.5 meters long in a normal contractile state and 9 meters long in a cadaver
    • Accessory digestive organs include salivary glands, teeth, tongue, exocrine pancreas, biliary system (liver and gallbladder), and appendix
    • Major structures in the GI tract include mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, and ileum), and large intestine (cecum, colon, and rectum)

    Key Processes of GIT

    • Motility: movement of food throughout the GI tract
    • Digestion and absorption of nutrients
    • Regulation of digestive processes through neural reflexes and hormonal pathways

    Gastrointestinal Problems

    • Symptoms may include pain, nausea, vomiting, dysphagia, anorexia, diarrhea, constipation, changing bowel movement, and GI bleeding
    • Diseases may be limited to the GI tract or present as systemic disorders with GI origin

    Gut Endocrine System

    • Produced by specialized endocrine cells in the mucosa of certain regions of the GI tract
    • Can have excitatory or inhibitory influences on digestive smooth muscle and exocrine gland cells
    • Examples of gut endocrine cells include enterochromaffin-like (ECL), G, and D cells in the stomach

    GIT Receptors

    • Receptor activation alters digestive activity through neural reflexes and hormonal pathways
    • Types of receptors include chemoreceptors, mechanoreceptors, and osmoreceptors

    Digestion and Absorption

    • Mechanical and chemical digestion occur in the mouth, with salivary amylase breaking down starch into maltose and α-limit dextrins
    • Lingual lipase breaks down complex lipids into fatty acids and glycerol
    • Most ingested food is absorbed indiscriminately, while calcium and iron absorption is adjusted to the body's needs

    Structure of GIT Wall

    • The four major layers of the GIT wall are mucosa, submucosa, muscularis externa, and serosa
    • The mucosal layer contains epithelial cells, exocrine gland cells, endocrine gland cells, and lamina propria
    • The submucosa provides distensibility and elasticity, while the muscularis externa contains smooth muscle layers that produce propulsive and mixing movements
    • The serosa secretes watery fluid to prevent friction between digestive organs and surrounding viscera

    Regulation of Digestion

    • Regulation requires the integrative control of GIT function, with coordination of motor, secretory, digestive, and absorptive functions
    • The autonomic nervous system, enteric nervous system, and gut endocrine system work together to regulate digestion
    • The autonomic nervous system coordinates activity among different regions of the digestive system and influences motility and secretion
    • The enteric nervous system is responsible for local reflexes and regulating gut function
    • The gut endocrine system regulates digestive processes through the release of hormones

    Overview of Gastrointestinal System

    • The GI tract is approximately 4.5 meters long in a normal contractile state and 9 meters long in a cadaver
    • Accessory digestive organs include salivary glands, teeth, tongue, exocrine pancreas, biliary system (liver and gallbladder), and appendix
    • Major structures in the GI tract include mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, and ileum), and large intestine (cecum, colon, and rectum)

    Key Processes of GIT

    • Motility: movement of food throughout the GI tract
    • Digestion and absorption of nutrients
    • Regulation of digestive processes through neural reflexes and hormonal pathways

    Gastrointestinal Problems

    • Symptoms may include pain, nausea, vomiting, dysphagia, anorexia, diarrhea, constipation, changing bowel movement, and GI bleeding
    • Diseases may be limited to the GI tract or present as systemic disorders with GI origin

    Gut Endocrine System

    • Produced by specialized endocrine cells in the mucosa of certain regions of the GI tract
    • Can have excitatory or inhibitory influences on digestive smooth muscle and exocrine gland cells
    • Examples of gut endocrine cells include enterochromaffin-like (ECL), G, and D cells in the stomach

    GIT Receptors

    • Receptor activation alters digestive activity through neural reflexes and hormonal pathways
    • Types of receptors include chemoreceptors, mechanoreceptors, and osmoreceptors

    Digestion and Absorption

    • Mechanical and chemical digestion occur in the mouth, with salivary amylase breaking down starch into maltose and α-limit dextrins
    • Lingual lipase breaks down complex lipids into fatty acids and glycerol
    • Most ingested food is absorbed indiscriminately, while calcium and iron absorption is adjusted to the body's needs

    Structure of GIT Wall

    • The four major layers of the GIT wall are mucosa, submucosa, muscularis externa, and serosa
    • The mucosal layer contains epithelial cells, exocrine gland cells, endocrine gland cells, and lamina propria
    • The submucosa provides distensibility and elasticity, while the muscularis externa contains smooth muscle layers that produce propulsive and mixing movements
    • The serosa secretes watery fluid to prevent friction between digestive organs and surrounding viscera

    Regulation of Digestion

    • Regulation requires the integrative control of GIT function, with coordination of motor, secretory, digestive, and absorptive functions
    • The autonomic nervous system, enteric nervous system, and gut endocrine system work together to regulate digestion
    • The autonomic nervous system coordinates activity among different regions of the digestive system and influences motility and secretion
    • The enteric nervous system is responsible for local reflexes and regulating gut function
    • The gut endocrine system regulates digestive processes through the release of hormones

    Gastrointestinal System Overview

    • The GI tract is approximately 4.5m long in its normal contractile state, but can stretch to 9m long in a cadaver
    • The GI tract has accessory organs, including salivary glands, teeth, tongue, exocrine pancreas, biliary system (liver and gallbladder), and appendix
    • The GI tract is innervated and regulated by the autonomic nervous system, enteric nervous system, and gut endocrine system

    Major Structures of the GI Tract

    • Mouth
    • Pharynx
    • Esophagus
    • Stomach
      • Has a thick muscle layer
      • Acts as a mixing chamber and holding reservoir
      • Converts bolus to chyme
      • Begins protein and triglyceride digestion
    • Small intestine
      • Divided into duodenum, jejunum, and ileum
      • Site of most nutrient absorption
    • Large intestine
      • Divided into cecum, colon, and rectum
      • Site of water and electrolyte absorption, and storage of feces

    Key Processes of the GI Tract

    • Motility: movement of food through the GI tract, controlled by the autonomic nervous system and enteric nervous system
    • Secretion: production of digestive enzymes and hormones by glands and cells in the GI tract
    • Digestion: breakdown of nutrients by digestive enzymes
    • Absorption: uptake of nutrients into the bloodstream

    Enteric Nervous System

    • Consists of two plexuses: myenteric plexus and submucosal plexus
    • Myenteric plexus controls motor activity of the GI tract
    • Submucosal plexus controls local absorption, secretion, and contraction
    • Regulated by the autonomic nervous system and gut endocrine system

    Regulation of Digestion

    • Requires integrative control of GI function
    • Involves coordination of motor, secretory, digestive, and absorptive functions
    • Regulated by the autonomic nervous system, enteric nervous system, and gut endocrine system

    Pharynx and Esophagus

    • Swallowing is controlled by the autonomic nervous system
    • Pharyngeal pressure receptors stimulate swallowing
    • Achalasia is a disorder characterized by difficulty swallowing due to lack of neuronal input and failure of the lower esophageal sphincter to relax

    Stomach

    • Acts as a mixing chamber and holding reservoir
    • Converts bolus to chyme
    • Begins protein and triglyceride digestion
    • Has a thick muscle layer

    Carbohydrate Digestion

    • Begins in the mouth with salivary amylase
    • Continues in the small intestine with pancreatic amylase and intestinal epithelial cell enzymes
    • Ends with the absorption of monosaccharides in the small intestine

    Protein Digestion

    • Begins in the stomach with pepsin
    • Continues in the small intestine with pancreatic enzymes and intestinal epithelial cell enzymes
    • Ends with the absorption of amino acids in the small intestine

    Peptic Ulcer

    • Caused by Helicobacter pylori in more than 80% of cases
    • H. pylori tunnel through the stomach's mucus layer and reside underneath, causing persistent inflammation
    • Weakens the gastric mucosal barrier, leading to pepsin and HCl damage
    • Other factors that contribute to peptic ulcers include alcohol and NSAIDs
    • Treatments include antibiotics, H-2 histamine receptor blockers, and proton pump inhibitors

    Digestion and Absorption

    • The digestive system involves the secretion of digestive juices, digestion of food, absorption of digested products, water, and electrolytes, circulation of blood, and control by nervous and hormonal systems.
    • Motility involves muscular contractions that mix food with digestive juice and facilitate absorption, and move food forward through the gastrointestinal tract (GIT).

    Motility

    • Smooth muscle is responsible for most of the motility in the GIT, while skeletal muscle is involved in the mouth and external anal sphincter.
    • Peristalsis is a movement along the tract involving sequential contraction and relaxation of adjacent smooth muscle.

    Segmentation

    • Segmentation involves mixing the contents of the GIT to promote digestion and absorption, and slow progression through the proximal small intestine.
    • Contractions are more frequent in the proximal small intestine, and are influenced by distension of the intestine, gastrin, and extrinsic nerve activity.
    • Parasympathetic stimulation enhances segmentation.

    Secretion

    • Exocrine secretion involves the release of digestive enzymes from the pancreas and stomach, while endocrine secretion involves the release of hormones such as gastrin and somatostatin.
    • Digestive secretions are typically reabsorbed back into the blood after participating in digestion.

    Digestion of Carbohydrates

    • Polysaccharides such as starch and glycogen are broken down into disaccharides and then into monosaccharides, which are absorbable units.
    • Enzymes such as salivary amylase and pancreatic amylase are involved in carbohydrate digestion.

    Digestion of Fat

    • Triglycerides are broken down into monoglycerides and free fatty acids, and then absorbed into the bloodstream.
    • Bile salts emulsify fat globules, allowing pancreatic lipase to break them down.

    Absorption

    • Absorption involves the uptake of small, absorbable units, water, vitamins, and electrolytes into the bloodstream.
    • Most of the ingested food is absorbed, with the exception of calcium and iron, which are absorbed according to the body's needs.

    Structure of GIT Wall

    • The GIT wall consists of four major layers: mucosa, submucosa, muscularis externa, and serosa.
    • The mucosa contains exocrine and endocrine gland cells, epithelial cells specialized for absorption, and a layer of smooth muscle.
    • The submucosa is a thick connective tissue layer that provides distensibility and elasticity, and contains larger blood and lymph vessels.
    • The muscularis externa is a major smooth muscle coat that produces propulsive and mixing movements.

    Regulation of Digestion

    • Regulation of digestion involves the integrative control of GIT function, and requires coordination of motor, secretory, digestive, and absorptive functions.
    • The autonomic nervous system, enteric nervous system, and gut endocrine system are involved in regulating digestion.
    • The autonomic nervous system influences motility and secretion by modifying the activity of intrinsic plexuses, altering the level of GI hormone secretion, or acting directly on smooth muscle and glands.

    Parasympathetic Innervation

    • Parasympathetic innervation arises from the medulla and sacral spinal cord, and controls the oesophagus to the ascending colon, and beyond the ascending colon, respectively.
    • Damage to the parasympathetic innervation can lead to gastroparesis.

    Integration of GI Smooth Muscle

    • Swallowing involves a voluntary stage, a pharyngeal stage, and an oesophageal stage, and is regulated by the autonomic nervous system.
    • The oesophageal stage involves the involuntary passage of the bolus through the oesophagus into the stomach.

    Digestive Enzymes

    • Trypsinogen: activated by enteropeptidase in duodenum, breaks down peptides into fragments
    • Chymotrypsinogen: activated by enteropeptidase in duodenum, breaks down peptides into fragments
    • Procarboxypeptidase: activated by enteropeptidase in duodenum, breaks down peptides into fragments
    • Aminopeptidases: hydrolyse peptide fragments into amino acids and small peptides, absorbable in the small intestine

    Fat Digestion

    • Triglycerides broken down into monoglycerides and free fatty acids
    • Lipase: hydrolyses triglycerides to fatty acids and monoglycerides, absorbable in the small intestine

    Regulation of Digestion

    • Requires integrative control of GIT function
    • GIT: self-regulating system of organs
    • Coordination of motor, secretory, digestive, and absorptive functions
    • Autonomic nervous system, enteric nervous system, and gut endocrine system involved in regulation

    Autonomic Nervous System

    • Parasympathetic nervous system: tends to increase smooth muscle motility and promotes secretion of digestive enzymes or hormones
    • Postsynaptic neurotransmitter: acetylcholine
    • Sympathetic nervous system: inhibits digestive tract contraction and secretion
    • Postsynaptic neurotransmitter: noradrenaline

    Enteric Nervous System

    • Intrinsic (enteric) nerves located in the submucosa and muscularis externa
    • Control motility, secretion, and absorption
    • Excitatory neurotransmitters: acetylcholine
    • Inhibitory neurotransmitters: vasoactive intestinal peptide, nitric oxide

    Gut Endocrine System

    • Produced by specialized endocrine cells in the mucosa of certain regions of GIT
    • Can have excitatory or inhibitory influences on digestive smooth muscle and exocrine gland cells
    • Examples: ECL, G, and D cells in the stomach

    GIT Receptors

    • Chemoreceptors: detect chemical composition of luminal fluid
    • Mechanoreceptors: detect stretch or tension in the gut wall
    • Osmoreceptors: detect osmotic composition of the luminal fluid
    • Receptor activation alters digestive activity through neural reflexes and hormonal pathways

    Mouth - Digestion

    • Mechanical and chemical digestion occur in the mouth
    • Mechanical digestion: chewing (mastication)
    • Chemical digestion: salivary amylase breaks down starch into maltose and α-limit dextrins, lingual lipase hydrolyses complex lipids into fatty acids and glycerol

    Saliva

    • Extrinsic autonomic nerve control: parasympathetic and sympathetic nervous systems
    • Parasympathetic nervous system: dominant role in salivary secretion, produces prompt and abundant flow of watery saliva rich in enzymes
    • Sympathetic nervous system: produces smaller volume of thick saliva rich in mucus

    Enteric Nervous System

    • Located in the GI tract, consisting of two plexuses: myenteric plexus (muscularis externa layer) and submucosal plexus (submucosa layer)
    • Controls GI motility, secretion, and absorption

    Myenteric Plexus

    • Linear plexus that runs the entire length of the GI tract
    • Controls motor activity, leading to:
      • Increased tone of the gut wall
      • Increased intensity of contractions
      • Increased rate of contractions
      • Increased peristalsis

    Submucosal Plexus

    • Controls local absorption, secretion, and contraction within each gut segment
    • Provides local control within the inner walls of each gut segment

    Regulation of Digestion

    • Requires integrative control of GI function, involving the autonomic nervous system and smooth muscle
    • Involves the coordination of motor, secretory, digestive, and absorptive functions

    Pharynx and Oesophagus

    • Swallowing (deglutition) involves three stages:
      1. Voluntary stage: bolus passed into oropharynx by tongue
      2. Pharyngeal stage: bolus stimulates stretch receptors in oropharynx, sending impulses to the deglutition center in the brain stem
      3. Oesophageal stage: involuntary passage of bolus into oesophagus
    • Preventing food from entering respiratory airways during swallowing:
      • Uvula elevated to prevent food from entering nasal passageways
      • Tight closure of the vocal folds (glottis)
      • Epiglottis folds backward to provide further protection

    Stomach

    • Acts as a mixing chamber and holding reservoir
    • Converts bolus to creamy paste (chyme)
    • Starch digestion continues, and protein and triglyceride digestion begins
    • Carbohydrate digestion: amylase breaks down polysaccharides to disaccharides and α-limit dextrins

    Protein Digestion

    • Proteins broken down to amino acids and small polypeptides
    • Stomach chief cells: pepsin breaks down protein to peptide fragments
    • Exocrine pancreas: trypsinogen, chymotrypsinogen, and procarboxypeptidase break down peptide fragments
    • Small intestine epithelial cells: enzymes (e.g., aminopeptidases) break down peptide fragments to amino acids

    Gastric Hormones

    • Gastrin:
      • Stimulates parietal and chief cells
      • Stimulates ECL cells to produce histamine
      • Increases HCl secretion
    • Histamine:
      • Released from ECL cells in response to Ach and gastrin
      • Acts locally on parietal cells to increase HCl secretion
    • Somatostatin:
      • Released from D cells in response to acid
      • Inhibits secretion by parietal cells, G cells, and ECL cells

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    Description

    Quiz on the basics of the gastrointestinal system, covering functions, processes, digestion, and regulation. Understand the autonomic nervous and smooth muscle system.

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