HANDOUT 3 GIT
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Questions and Answers

What is the main function of enzymes in the digestion process?

  • To maintain a concentration gradient between lumen and blood
  • To remove absorbed nutrients
  • To increase the surface area of the mucosa
  • To catalyze carbohydrates, lipids, and proteins (correct)

    • In which part of the gastrointestinal tract does the vast majority of absorption occur?

  • Small intestine (correct)
  • Stomach
  • Esophagus
  • Colon

    • What is responsible for the final removal of electrolytes and water?

  • Villi
  • Colon (correct)
  • Circular Folds
  • Mucosal folds

    • Which structure increases the surface area of the mucosa threefold?

    <p>Mucosal folds</p> Signup and view all the answers

    What is the role of the capillary network in the villus?

    <p>To remove absorbed nutrients quickly</p> Signup and view all the answers

    How much does the net increase in surface area occur due to the micrvilli?

    <p>20 folds</p> Signup and view all the answers

    What is the primary driving force for water absorption in the small intestine?

    <p>Active transport of Na+ at the lumenal membrane</p> Signup and view all the answers

    What is the role of bile salts in lipid digestion?

    <p>Emulsify lipid into small droplets in the duodenum</p> Signup and view all the answers

    Which hormone increases Na+ absorption in the colon to conserve water and Na+ during dehydration?

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

    What is the primary mechanism for Ca++ absorption across the intestinal epithelial cell?

    <p>Active transport at the lumenal membrane</p> Signup and view all the answers

    Which vitamin is primarily absorbed in the ileum?

    <p>Vitamin B12</p> Signup and view all the answers

    What is the role of calbindin in Ca++ absorption?

    <p>Transporting Ca++ across the cell by primary active process</p> Signup and view all the answers

    How are chylomicrons expelled from the intestinal epithelial cells?

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

    What promotes iron absorption in the small intestine?

    <p>Acidic pH in the stomach and vitamin C</p> Signup and view all the answers

    How do phospholipids and cholesterol diffuse out of micelles across the gut wall?

    <p>By simple diffusion into the epithelial cell</p> Signup and view all the answers

    What is the primary driving force for water absorption in the small intestine?

    <p>Active transport of Na+ at the lumenal membrane</p> Signup and view all the answers

    What is absorbed mainly in the upper part of the small intestine (duodenum and jejunum)?

    <p>Fe++ and vitamin C</p> Signup and view all the answers

    What is absorbed passively in small intestine but usually secreted in exchange for Na+ in colon?

    <p>K+</p> Signup and view all the answers

    Which enzyme is responsible for the initial digestion of carbohydrates in the oral cavity?

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

    What is the primary function of pepsin in protein digestion?

    <p>Hydrolyzing large peptides into smaller polypeptides</p> Signup and view all the answers

    How are di- and tri-peptides transported into the enterocyte for protein absorption?

    <p>Active transport with Na+ pump as a co-transporter</p> Signup and view all the answers

    Which enzyme is responsible for the final hydrolysis of glucose polymers and disaccharides into monosaccharides?

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

    What is the role of bile in fat digestion and absorption?

    <p>Emulsifying lipids to aid in their digestion</p> Signup and view all the answers

    Which molecule is responsible for solubilizing lipids and aiding in their digestion?

    <p>Bile salts</p> Signup and view all the answers

    What happens to salivary alpha-amylase (ptyalin) in the stomach?

    <p>It is inactivated at acidic pH</p> Signup and view all the answers

    How does glucose primarily enter the epithelial cells for absorption?

    <p>$Na^-$ linked carrier transport</p> Signup and view all the answers

    Which enzyme is responsible for digesting 50-80% of starch in the small intestine?

    <p>\beta-Amylase</p> Signup and view all the answers

    What is the primary function of smooth muscle cells of the muscularis mucosa in the intestines?

    <p>Wave villi in the lumen to facilitate absorption</p> Signup and view all the answers

    How are small peptides transported into enterocytes for protein absorption?

    <p>Active transport with Na+ pump as a co-transporter</p> Signup and view all the answers

    What is the total net increase in surface area due to the intestinal mucosal folds, villi, and microvilli?

    <p>600 folds</p> Signup and view all the answers

    What is the primary function of the capillary network in the villus?

    <p>To maintain a concentration gradient between lumen and blood in capillaries</p> Signup and view all the answers

    Where does the vast majority of absorption occur in the gastrointestinal tract?

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

    What is the role of bile salts in lipid digestion?

    <p>Emulsify lipids to aid in their digestion</p> Signup and view all the answers

    Which structure increases the absorptive surface area of the mucosa threefold?

    <p>Intestinal Mucosal Folds</p> Signup and view all the answers

    What is responsible for the final removal of electrolytes and water in the gastrointestinal tract?

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

    Which enzyme digests 50-80% of starch in the small intestine?

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

    What is the primary driving force for water absorption in the small intestine?

    <p>Increased osmotic pressure</p> Signup and view all the answers

    How does fructose primarily enter the epithelial cells for absorption?

    <p>Passive diffusion</p> Signup and view all the answers

    What is the primary role of bile salts in lipid digestion?

    <p>Solubilize lipids and aid in their digestion</p> Signup and view all the answers

    What is responsible for the final removal of electrolytes and water?

    <p>Peptidases inside the cytosol</p> Signup and view all the answers

    What is absorbed mainly in the upper part of the small intestine (duodenum and jejunum)?

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

    What is the primary function of smooth muscle cells of the muscularis mucosa in the intestines?

    <p>Move folds to permit spreading of chyme</p> Signup and view all the answers

    Which molecule is responsible for solubilizing lipids and aiding in their digestion?

    <p>Bile salts</p> Signup and view all the answers

    What is absorbed passively in the small intestine but usually secreted in exchange for Na+ in colon?

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

    What is absorbed primarily in the upper part of the small intestine (duodenum and jejunum)?

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

    What promotes iron absorption in the small intestine?

    <p>Bile salts</p> Signup and view all the answers

    What is absorbed mainly in the upper part of the small intestine (duodenum and jejunum)?

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

    What is the primary driving force for water absorption in the small intestine?

    <p>Active transport of sodium</p> Signup and view all the answers

    What is the main function of enzymes in the digestion process?

    <p>To catalyze the hydrolysis of macromolecules into smaller molecules for absorption</p> Signup and view all the answers

    Which hormone increases Na+ absorption in the colon to conserve water and Na+ during dehydration?

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

    How are phospholipids and cholesterol transported across the gut wall?

    <p>Via passive diffusion through the lumenal membrane</p> Signup and view all the answers

    What is the role of calbindin in Ca++ absorption?

    <p>It transports Ca++ across the cell by primary active process</p> Signup and view all the answers

    Which vitamin is primarily absorbed in the ileum?

    <p>Vitamin B12</p> Signup and view all the answers

    What happens to salivary alpha-amylase (ptyalin) in the stomach?

    <p>It gets denatured and becomes inactive due to stomach acidity</p> Signup and view all the answers

    What promotes iron absorption in the small intestine?

    <p>Acidic pH in the stomach and vitamin C</p> Signup and view all the answers

    How does glucose primarily enter the epithelial cells for absorption?

    <p>Via active transport by glucose carriers</p> Signup and view all the answers

    What is absorbed passively in small intestine but usually secreted in exchange for Na+ in colon?

    <p>Chloride (Cl-)</p> Signup and view all the answers

    What is responsible for the final removal of electrolytes and water?

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

    Which enzyme is responsible for digesting 50-80% of starch in the small intestine?

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

    The vast majority of absorption occurs in the colon.

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

    The net increase in the surface area due to mucosal folds, villi, and microvilli is about 600 folds.

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

    The lumenal surface of the epithelial cells has macrovilli, which increase surface area 20 folds.

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

    The primary function of the capillary network in the villus is to add nutrients to the absorbed substances.

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

    The small intestine has specialized structures to decrease the absorptive capacity by decreasing the absorptive surface area of the mucosa.

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

    Most nutrients are absorbed before reaching the ileum.

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

    Chylomicrons are expelled from the epithelial cells by endocytosis.

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

    The conjugated bile acids are more hydrophobic than the sterol nucleus.

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

    The primary driving force for water absorption in the small intestine is the active transport of Na+ at the basolateral membrane.

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

    Iron absorption is mainly promoted by alkaline pH in the stomach and vitamin C.

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

    Bile salts form micelles in an aqueous environment by orienting the hydrophobic portion toward the shell.

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

    The absorption of electrolytes is greatest in the ileum and increases toward the duodenum.

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

    The primary function of smooth muscle cells of the muscularis mucosa in the intestines is the absorption of lipids.

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

    Bile salts are absorbed actively in the terminal ileum.

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

    The effect of aldosterone mainly occurs in the small intestine to enhance Na+ absorption.

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

    Vitamin B12 is primarily absorbed in the duodenum.

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

    Iron stored in the epithelial cell is transported into the blood where it binds to ferritin as needed.

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

    Phosphates, oxalates, and phytic acid promote iron absorption in the small intestine.

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

    The final digestion of carbohydrates results in the formation of glucose, fructose, and galactose.

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

    The enzyme ptyalin is inactivated in the acidic pH of the stomach.

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

    Lactase is responsible for splitting maltose and other glucose polymers into glucose.

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

    Galactose enters the epithelial cells using a carrier linked to Na+.

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

    Protein digestion in the stomach is limited because the pepsin and HCl cannot attack the interior of the food mass.

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

    Bile salts are secreted by the liver to act in the lumen of the intestine, aiding in the solubilization and digestion of lipids.

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

    Amino acids are primarily transported into the enterocytes using a Na+ dependent carrier.

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

    The activity of pepsin results in hydrolysis of about 20% of proteins that enter the stomach, converting them into peptones and smaller polypeptides.

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

    Fructose enters into the epithelial cells by facilitated diffusion using a carrier not linked to Na+.

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

    The process of carbohydrate digestion begins in the oral cavity with the enzyme ptyalin.

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

    Small peptides are transported into enterocytes by a carrier mediated transport system, which depends upon the activity of Na+ pump to maintain a chemical gradient for Na+ across the lumenal membrane.

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

    Bile solubilizes lipids and aids in their digestion by acting as an emulsifier to increase lipid surface area for digestion.

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

    Most nutrients are absorbed before reaching the ileum.

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

    The lumenal surface of the epithelial cells has microvilli, which increase surface area 20 folds.

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

    Vitamin B12 is primarily absorbed in the duodenum.

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

    Bile solubilizes lipids and aids in their digestion by acting as an emulsifier to increase lipid surface area for digestion.

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

    The effect of aldosterone mainly occurs in the small intestine to enhance Na+ absorption.

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

    The primary function of the capillary network in the villus is to add nutrients to the absorbed substances.

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

    Ptyalin, a salivary alpha-amylase, has an optimum activity at acidic pH.

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

    The process of carbohydrate digestion begins in the stomach.

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

    Pepsin and HCl in the stomach can fully attack the interior of the food mass for protein digestion.

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

    Bile salts are hydrophobic molecules that do not solubilize lipids in the lumen of the intestine.

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

    Glucose primarily enters the epithelial cells for absorption using a carrier not linked to Na+.

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

    The absorption of electrolytes is greatest in the duodenum and decreases toward the ileum.

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

    Proteolytic enzymes of the pancreas include endopeptidases, but not exopeptidases.

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

    Fructose primarily enters the epithelial cells for absorption using the same carrier as glucose and galactose.

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

    Bile is not required for fat digestion and absorption.

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

    Cellulose, a glucose polymer, is digestible by enzymes of the gut.

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

    Chylomicrons are expelled from the epithelial cells by exocytosis, not endocytosis.

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

    The final digestion of carbohydrates results in glucose only.

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

    Chylomicrons are expelled from the epithelial cells by endocytosis.

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

    Vitamin B12 is primarily absorbed in the duodenum.

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

    Bile salts are absorbed actively in the terminal ileum.

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

    The primary driving force for water absorption in the small intestine is the active transport of Na+ at the basolateral membrane.

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

    The final digestion of carbohydrates results in the formation of glucose, fructose, and galactose.

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

    Bile solubilizes lipids and aids in their digestion by acting as an emulsifier to increase lipid surface area for digestion.

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

    The activity of pepsin results in hydrolysis of about 20% of proteins that enter the stomach, converting them into peptones and smaller polypeptides.

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

    Lactase is responsible for splitting maltose and other glucose polymers into glucose.

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

    Chylomicrons are expelled from the intestinal epithelial cells by endocytosis.

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

    Protein digestion in the stomach is limited because the pepsin and HCl cannot attack the interior of the food mass.

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

    What is absorbed passively in small intestine but usually secreted in exchange for Na+ in colon?

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

    The detailed mechanisms of iron absorption are still unsettled.

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

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