Question 1

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

Accepted Answer

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Question 2

The liver receives venous blood coming directly from the digestive tract, and arterial blood coming from the aorta.

Accepted Answer

This statement is true. The hepatic portal vein carries blood from the digestive tract to the liver, while the hepatic artery carries oxygenated blood from the aorta to the liver.

Question 3

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 4

The myenteric plexus is a nerve network located in the submucosa.

Accepted Answer

The myenteric plexus is a nerve network located between the longitudinal and circular smooth muscle layers of the muscularis externa in the gastrointestinal tract. It is not located in the submucosa.

Question 5

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 begins in the stomach with the inactive precursor enzyme pepsinogen, which is activated to pepsin by the acidic environment of the stomach. Pepsin breaks down dietary proteins into smaller peptides. The partially digested food then enters the duodenum, where pancreatic enzymes such as trypsin, chymotrypsin, and carboxypeptidase further break down the peptides into smaller peptide fragments. These peptide fragments are then further broken down into individual amino acids by enzymes located on the surface of the small intestinal cells called brush border enzymes.

Question 6

Both amino acids and glucose are absorbed by secondary active transport by the small intestinal epithelial cells.

Accepted Answer

Both amino acids and glucose are absorbed by secondary active transport by the small intestinal epithelial cells using specific transporters such as the sodium-glucose cotransporter (SGLT) and the sodium-coupled amino acid transporter (SIT).

Question 7

The primary factor governing the rate of gastric emptying is the volume of the gastric contents.

Accepted Answer

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Question 8

Intrinsic factor is necessary for the absorption of vitamin B₁₂.

Accepted Answer

Intrinsic factor is necessary for the absorption of vitamin B12.

Question 9

Considerable vitamin absorption occurs passively in the stomach.

Accepted Answer

Vitamin absorption primarily occurs in the small intestine, not the stomach.

Question 10

Haustral contractions propel the feces one-third to three-quarters the length of the colon in a few seconds.

Accepted Answer

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Question 11

The main sympathetic nerve supply to the digestive tract is the vagus.

Accepted Answer

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Question 12

Gastric secretion occurs only when food is present in the stomach.

Accepted Answer

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Question 13

After food has been chewed and mixed with salivary secretion, it is referred to as chyme.

Accepted Answer

After food has been chewed and mixed with salivary secretion, it is referred to as bolus. Chyme is the name given to the partially digested food mixed with stomach secretions.

Question 14

Bile salts are derivatives of cholesterol.

Accepted Answer

Bile salts are synthesized in the liver from cholesterol and play a key role in the digestion and absorption of dietary fats.

Question 15

The primary absorption of nutrients, water, and electrolytes takes place in the large intestine, converting chyme to fecal material.

Accepted Answer

While the large intestine does absorb some water and electrolytes, the primary absorption of nutrients and water takes place in the small intestine. The large intestine's main function is to reabsorb water and electrolytes and form fecal material from the remaining chyme.

Question 16

Glycogen is stored in the liver.

Accepted Answer

Glycogen is indeed stored in the liver.

Question 17

The function of mixing movements is to promote digestion and facilitate absorption.

Accepted Answer

Mixing movements such as segmentation and peristalsis help mix food with digestive enzymes and break it down into smaller pieces, which promotes digestion. They also help move nutrients across the intestinal wall for absorption.

Question 18

In cirrhosis, damaged hepatocytes are permanently replaced by an overgrowth of connective tissue.

Accepted Answer

Cirrhosis is characterized by fibrosis and scarring of the liver tissue, leading to loss of functioning hepatocytes and overgrowth of connective tissue. This process is irreversible and can eventually lead to liver failure.

Question 19

The principal clinical manifestation of pancreatic exocrine insufficiency is incomplete protein digestion resulting from deficiency of the powerful pancreatic proteolytic enzymes.

Accepted Answer

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Question 20

The only function of chewing is to break food up into smaller pieces and soften it by mixing it with saliva to facilitate swallowing.

Accepted Answer

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Quiz 14: The Urinary System