Question 1

Bile salts are important in fat digestion and absorption.

Accepted Answer

Bile salts emulsify dietary fats, breaking them down into smaller droplets, which allows for easier digestion and absorption. Without bile salts, fat digestion and absorption would be less efficient.

Question 2

Bile salts are derivatives of cholesterol.

Accepted Answer

Bile salts are formed from cholesterol in the liver and are important for the digestion and absorption of dietary fats in the small intestine.

Question 3

The primary factor responsible for forward propulsion of chyme through the small intestine is mass movements.

Accepted Answer

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Question 4

Fat is absorbed into the lymph in the form of micelles.

Accepted Answer

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Question 5

Migration of a new intestinal epithelial cell from the crypt at the base of the villus to the tip of the villus requires about three weeks.

Accepted Answer

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Question 6

Sodium can be absorbed both actively and passively.

Accepted Answer

Sodium can be absorbed actively through the sodium-potassium pump, which requires energy, or passively through diffusion, which does not require energy.

Question 7

Digestive enzymes produced by the small intestine are not secreted into the lumen but act intracellularly.

Accepted Answer

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Question 8

Chylomicrons are aggregates of bile salts,monoglycerides,and free fatty acids.

Accepted Answer

Chylomicrons are not aggregates of bile salts, monoglycerides, and free fatty acids. Instead, they are lipoprotein particles composed of triglycerides, phospholipids, cholesterol, and apolipoproteins that transport dietary lipids from the intestine to other tissues in the body.

Question 9

The main motility seen in the small intestine during digestion of a meal is the migrating motility complex.

Accepted Answer

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Question 10

Bilirubin aids fat digestion and absorption.

Accepted Answer

Bilirubin is a waste product that is removed from the body through bile. Bile helps in the digestion and absorption of fats, but bilirubin itself does not aid in these processes.

Question 11

Lipase breaks down proteins via hydrolysis.

Accepted Answer

Lipase breaks down fats via hydrolysis, not proteins.

Question 12

Excessive small intestinal motility can lead to constipation because there is less time for absorption to take place.

Accepted Answer

Excessive small intestinal motility can actually lead to diarrhea because there is less time for absorption to take place. Constipation typically occurs when there is slow movement of stool through the colon, not the small intestine.

Question 13

Microvilli establish a brush border in the small intestine.

Accepted Answer

Microvilli are small finger-like projections that extend from the surface of absorptive cells in the small intestine, creating a brush border. This increases the surface area for nutrient absorption.

Question 14

The main function of the ileocecal valve/sphincter is to prevent small intestinal contents from entering the large intestine before digestion of food is completed.

Accepted Answer

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Question 15

The small intestinal epithelium actively secretes digestive enzymes into the intestinal lumen.

Accepted Answer

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Question 16

Amino acids and glucose are both absorbed by secondary active transport by the small intestinal epithelial cells.

Accepted Answer

Amino acids and glucose are both absorbed by secondary active transport through specific transporters located on the apical membrane of small intestinal epithelial cells. This process is driven by the electrochemical gradient generated by the sodium-potassium ATPase pump.

Question 17

The ileocecal juncture serves as a barrier to prevent bacteria-laden contents of the large intestine from contaminating the small intestine.

Accepted Answer

The ileocecal juncture is a sphincter-like muscle that regulates the flow of contents between the small and large intestine. It serves as a barrier to prevent bacteria and other contents from the large intestine from flowing back up into the small intestine.

Question 18

CCK causes relaxation of the sphincter of Oddi.

Accepted Answer

CCK (cholecystokinin) is a hormone released by the small intestine in response to the presence of fat and protein in the duodenum. It causes contraction of the gallbladder to release bile into the small intestine and relaxation of the sphincter of Oddi which allows bile and pancreatic juice to flow into the duodenum.

Question 19

Protein digestion begins in the stomach under the influence of pepsinogen,continues in the duodenal lumen under the influence of pancreatic proteolytic enzymes,and is completed intracellularly in the small intestinal brush border.

Accepted Answer

This statement is true. Protein digestion starts in the stomach with the activation of pepsinogen to pepsin, which breaks down large protein molecules. The partially digested proteins then enter the duodenum where pancreatic proteolytic enzymes such as trypsin, chymotrypsin, and carboxypeptidase continue the breakdown of peptides into smaller peptides and amino acids. Finally, the last stage of protein digestion occurs in the brush border of the small intestine, where small peptides are broken down to individual amino acids by enzymes like dipeptidases and aminopeptidases, and the amino acids are absorbed into the bloodstream.

Question 20

Most of the fluid presented to the small intestine for absorption has been ingested.

Accepted Answer

Most of the fluid presented to the small intestine for absorption actually comes from the body itself, in the form of digestive juices secreted by the salivary glands, stomach, pancreas, liver, and small intestine, rather than directly from ingested fluids.

Quiz 14: The Digestive System