HANDOUT 3 GIT

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

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

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

Which structure increases the surface area of the mucosa threefold?

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

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

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

What is the role of bile salts in lipid digestion?

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

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

Which vitamin is primarily absorbed in the ileum?

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

How are chylomicrons expelled from the intestinal epithelial cells?

What promotes iron absorption in the small intestine?

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

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

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

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

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

What is the primary function of pepsin in protein digestion?

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

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

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

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

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

How does glucose primarily enter the epithelial cells for absorption?

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

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

How are small peptides transported into enterocytes for protein absorption?

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

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

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

What is the role of bile salts in lipid digestion?

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

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

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

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

How does fructose primarily enter the epithelial cells for absorption?

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

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

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

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

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

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

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

What promotes iron absorption in the small intestine?

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

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

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

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

How are phospholipids and cholesterol transported across the gut wall?

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

Which vitamin is primarily absorbed in the ileum?

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

What promotes iron absorption in the small intestine?

How does glucose primarily enter the epithelial cells for absorption?

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

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

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

The vast majority of absorption occurs in the colon.

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

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

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

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

Most nutrients are absorbed before reaching the ileum.

Chylomicrons are expelled from the epithelial cells by endocytosis.

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

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

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

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

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

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

Bile salts are absorbed actively in the terminal ileum.

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

Vitamin B12 is primarily absorbed in the duodenum.

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

Most nutrients are absorbed before reaching the ileum.

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

Vitamin B12 is primarily absorbed in the duodenum.

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

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

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

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

The process of carbohydrate digestion begins in the stomach.

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

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

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

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

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

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

Bile is not required for fat digestion and absorption.

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

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

The final digestion of carbohydrates results in glucose only.

Chylomicrons are expelled from the epithelial cells by endocytosis.

Vitamin B12 is primarily absorbed in the duodenum.

Bile salts are absorbed actively in the terminal ileum.

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

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

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

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

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

Chylomicrons are expelled from the intestinal epithelial cells by endocytosis.

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

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

The detailed mechanisms of iron absorption are still unsettled.