Anatomy and Physiology of the Digestive Tract

Question 1

What do chief cells do and where are they located?

Answer 1

The chief cells of the stomach secrete lipase.

Question 2

What does the lipase in the stomach do?

Answer 2

Breaks down dietary triglycerides (triacylglycerols) into free fatty acids and diglycerides (diacylglycerols), and pepsinogen (the precursor of pepsin, which initiates the hydrolysis of food proteins).

Question 3

What do parietal cells do and where are they located?

Answer 3

The parietal cells of the stomach secrete Intrinsic factor.

Question 4

What does the Intrinsic factor in the stomach do?

Answer 4

A small protein required for absorption of vitamin B12, and HCl.

Question 5

What do mucous cells do and where are they located?

Answer 5

Mucous cells of the stomach secrete mucus containing glycoproteins and bicarbonate.

Question 6

What does the mucus containing glycoproteins and bicarbonate in the stomach do?

Answer 6

Protect the gastric mucosa from acid damage and

auto digestion.

Question 7

What does Gastric acid do and where is it located?

Answer 7

In the stomach. Gastric acid performs a number of preliminary digestive roles that require an acidic environment, including destruction of microorganisms, activation of pepsinogen to pepsin, activation of intrinsic factor, denaturation (loss of three-dimensional conformation) of macromolecules, and facilitation of the breakdown of protein and polypeptides by pepsin.

Question 8

In the stomach, what triggers gastrin secretion and what secretes it?

Answer 8

The presence of food protein. It is secreted by gastric endocrine cells.

Question 9

What acts on gastric parietal and chief cells to stimulate intragastric secretion of HCL and pepsinogen.

Answer 9

Gastrin

Question 10

What stimulates gastric peristalsis and maintains the proliferation of gastric parietal cells.

Answer 10

Gastrin

Question 11

What sections of the small intestine are the major sites of nutrient absorption?

Answer 11

The jejunum and Ileum

Question 12

What does Acidic chyme do?

Answer 12

Acidic chyme entering the proximal duodenum stimulates the enteric secretion of secretin into the systemic circulation.

Question 13

What does secretin do?

Answer 13

Secretin stimulates pancreatic secretion of bicarbonate into the ductal system that terminates in the common bile duct.

Question 14

What stimulates cholecystokinin (CCK) into the

systemic circulation?

Answer 14

Fat or protein entering the proximal duodenum.

Question 15

What does cholecystokinin (CCK) stimulate?

Answer 15

Cholecystokinin stimulates pancreatic secretion of zymogens (inactive digestive enzyme precursors) into the ductal system and stimulates gall bladder
contraction, propelling bile into the common bile duct.

Question 16

What converts trypsinogen to trypsin?

Answer 16

Enterokinase

Question 17

What converts the other zymogens to

elastase, chymotrypsin, colipase, carboxypeptidase A and carboxypeptidase B?

Answer 17

Trypsin

Question 18

Carboxypeptidases require what mineral to cleave single carboxyterminal amino acids from polypeptides.

Answer 18

zinc

Question 19

What does the pancreas secrete to digest starches?

Answer 19

amylase

Question 20

What does the pancreas secrete to hydrolyze dietary fats that have been emulsified by bile salts into fatty acids and glycerol?

Answer 20

Lipase

Question 21

What is the primary role of the liver in food digestion and nutrient absorption?

Answer 21

The excretion of bile, a watery greenish fluid stored in the gallbladder.

Question 22

What contains cholic acid, chenodeoxycholic acid, taurine, glycine, cholesterol, electrolytes and water (6 to 7 L/day on average in adults).

Answer 22

Bile

Question 23

Monoglycerides, free fatty acids, cholesterol, phospholipid digestion products and other fat soluble
food components cannot readily penetrate the unstirred water layer that separates the 25 epithelial surface of the small intestine from the intestinal lumen. Their absorption depends on what?

Answer 23

Their absorption depends on their ability to aggregate spontaneously with bile salts and become incorporated within vaguely spherical clusters of bile salts called micelles.

Question 24

What are micelles?

Answer 24

Collections of lipid soluble dietary subcomponents surrounded by a layer of water soluble bile salts.

Question 25

Within the endoplasmic reticulum of enterocytes, lipids and lipid soluble compounds are repackaged into large protein-coated (and therefore water soluble) what?

Answer 25

chylomicrons

Question 26

Antimicrobial defenses within the intestinal tract rely heavily on the secretion of secretory IgA (sIgA) by what?

Answer 26

Antimicrobial defenses within the intestinal tract rely heavily on the secretion of secretory IgA (sIgA) by gut-associated lymphoid tissue (GALT).

Question 27

The GALT contains what?

Answer 27

About 50% to 60% of the total number of immune cells in the body, scattered throughout the intestinal tract.

Question 28

As the “first line of defense” against

environmental assault, GALT provides what?

Answer 28

Both cell-mediated immunity and humoral immunity

via secretory IgA.