Question 1

Which of the following best explains why intrinsic factor secretion by parietal cells is essential to life?

Accepted Answer

It is required for the absorption of vitamin B12, which is necessary for erythropoiesis. Without it, pernicious anemia develops.

Question 2

Which phase of gastric secretion is primarily triggered by the sight, smell, taste, or thought of food, and what is the main neural pathway involved?

Accepted Answer

Cephalic phase; vagus nerve (parasympathetic long reflex)

Question 3

Which combination of chemical signals most strongly stimulates acid secretion from parietal cells in the stomach?

Accepted Answer

Histamine, acetylcholine (ACh), and gastrin together

Question 4

What is the primary function of bile salts in digestion?

Accepted Answer

Emulsification of fats to increase surface area for lipase action

Question 5

A patient with a blockage of the common bile duct would have difficulty digesting which type of nutrient the most?

Accepted Answer

Lipids

Question 6

Which hormone is released in response to fatty chyme entering the duodenum and stimulates both gallbladder contraction and pancreatic enzyme secretion?

Accepted Answer

Cholecystokinin (CCK)

Question 7

What is the main physiological reason why carbohydrate-rich chyme empties from the stomach faster than fatty chyme?

Accepted Answer

Fatty chyme triggers the release of enterogastrones, which inhibit gastric motility and slow emptying.

Question 8

Which of the following best describes the mechanism by which parietal cells secrete hydrochloric acid (HCl) into the stomach lumen?

Accepted Answer

H$$_2O $$and CO$$_2$$ combine to form H$$_2CO$_3$$, which dissociates into H$$^+$$ and HCO$$_3^-$$; H$$^+ is $$pumped into the lumen via H$$^+/K$^+$$ ATPase, and HCO$$_3^- is $$exchanged for Cl$$^- in $$the interstitial fluid.

Question 9

Which of the following is a direct result of the 'alkaline tide' that occurs during gastric acid secretion?

Accepted Answer

An increase in blood pH due to the movement of HCO$$_3^-$$ into the bloodstream

Question 10

Which of the following best explains why pepsin is secreted as an inactive precursor (pepsinogen) by chief cells?

Accepted Answer

To prevent autodigestion of the chief cells and gastric mucosa

Question 11

Which of the following is NOT a function of the liver?

Accepted Answer

Secretion of digestive enzymes into the duodenum

Question 12

Which structure is responsible for the majority of enzymatic digestion of chyme in the small intestine?

Accepted Answer

Pancreas

Question 13

A patient has a mutation that prevents the recycling of bile salts via the enterohepatic circulation. Which of the following is the most likely consequence?

Accepted Answer

Decreased efficiency of lipid digestion and absorption

Question 14

Which of the following cell types in the small intestine is primarily responsible for secreting antimicrobial agents such as defensins and lysozyme?

Accepted Answer

Paneth cells

Question 15

Which of the following best describes the role of secretin in digestion?

Accepted Answer

It stimulates the pancreas and bile ducts to secrete a bicarbonate-rich fluid to neutralize acidic chyme.

Question 16

Which of the following modifications of the small intestine increases surface area for absorption and slows the movement of chyme?

Accepted Answer

Circular folds (plicae circulares)

Question 17

Which of the following best explains why only small particles and liquids are allowed to pass through the pyloric valve into the duodenum?

Accepted Answer

To prevent the duodenum from being overwhelmed by too much chyme or acidity

Question 18

Which of the following is the correct sequence for the activation of pancreatic proteases in the small intestine?

Accepted Answer

Enteropeptidase activates trypsinogen to trypsin, which then activates chymotrypsinogen and procarboxypeptidase.

Question 19

A patient with a deficiency in brush border enzymes would have the most difficulty digesting which type of nutrient?

Accepted Answer

Disaccharides (e.g., lactose, sucrose)

Digestive System Part 2: Stomach, Liver, Gallbladder, Pancreas, and Small Intestine

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