Question 1

Which of the following best describes the function of villi and microvilli in the small intestine?

Accepted Answer

They increase the surface area for absorption of nutrients.

Question 2

Peristalsis is essential for moving food through the digestive tract. Which statement best describes peristalsis?

Accepted Answer

It is the rhythmic contraction and relaxation of smooth muscle that propels food forward.

Question 3

The stomach mucosal barrier is crucial for protecting the stomach lining. Which anatomical factors contribute to this barrier?

Accepted Answer

Tight junctions between epithelial cells, a thick layer of bicarbonate-rich mucus, and rapid cell turnover.

Question 4

Which of the following best explains the difference between long and short reflexes in the GI tract?

Accepted Answer

Long reflexes involve the central nervous system, while short reflexes are mediated by the enteric nervous system.

Question 5

The sight or smell of food can trigger a series of events in the GI tract. Which phase of gastric secretion does this represent, and what is the primary mechanism?

Accepted Answer

Cephalic phase; neural stimulation via the vagus nerve.

Question 6

Which substances are absorbed in the stomach under normal physiological conditions?

Accepted Answer

Alcohol and some drugs such as aspirin.

Question 7

Gastrin, Secretin, and Cholecystokinin are hormones that regulate GI function. Which statement correctly matches each hormone to its primary action?

Accepted Answer

Gastrin stimulates gastric acid secretion; Secretin stimulates bicarbonate release from the pancreas; Cholecystokinin stimulates gallbladder contraction and pancreatic enzyme secretion.

Question 8

Bile salts play a critical role in digestion. What is their function and chemical composition?

Accepted Answer

They emulsify fats and are composed of cholesterol derivatives conjugated with amino acids.

Question 9

Hepatocytes perform several functions related to GI physiology. Which of the following is NOT a function of hepatocytes?

Accepted Answer

Secretion of digestive enzymes into the duodenum.

Question 10

What is the difference between a bolus and chyme?

Accepted Answer

A bolus is a mass of chewed food ready to be swallowed; chyme is the semi-liquid mixture of food and gastric secretions in the stomach.

Question 11

What is the primary function of the hepatic portal circulation?

Accepted Answer

To transport absorbed nutrients from the GI tract to the liver for processing.

Question 12

During the gastric phase of secretion, which mechanisms regulate acid production?

Accepted Answer

Both neural (vagus nerve) and hormonal (gastrin) stimulation increase HCl secretion.

Question 13

Why is the low pH of the stomach important for digestion?

Accepted Answer

It activates pepsinogen to pepsin and denatures proteins for enzymatic breakdown.

Question 14

Which enzyme is secreted by the stomach and what macromolecule does it attack?

Accepted Answer

Pepsin; it digests proteins.

Question 15

Protease enzymes in the GI tract are secreted in an inactive form. What activates them?

Accepted Answer

Exposure to acidic pH and cleavage by other proteases (e.g., pepsinogen activated by HCl, trypsinogen activated by enterokinase).

Question 16

Saliva has several important functions. Which of the following is NOT a function of saliva?

Accepted Answer

Emulsification of fats.

Question 17

What is the purpose of intrinsic factor in the stomach?

Accepted Answer

It is required for the absorption of vitamin B12 in the small intestine.

Question 18

Which equation best represents the regulation of HCl secretion in the stomach?

Accepted Answer

HCl secretion is stimulated by gastrin, acetylcholine, and histamine: $$	ext{HCl} \uparrow 	ext{when} \ 	ext{Gastrin} + 	ext{ACh} + 	ext{Histamine}$$

Question 19

Which cells in the stomach secrete hydrochloric acid (HCl)?

Accepted Answer

Parietal cells.

Question 20

What is the function of goblet cells in the GI tract?

Accepted Answer

They secrete mucus to protect and lubricate the lining of the GI tract.

Anatomy & Physiology: Digestive System Study Guide

Study Guide - Practice Questions

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