Chapter 5: Digestion, Absorption, and Metabolism

Question 1

The process of digestion involves _____ and _____ actions.

Answer 1

mechanical, chemical

For nutrients to be delivered to the cells, food goes through a series of mechanical and chemical changes.

Question 2

The rhythmic contractions of the stomach and intestine that propel food along are called

Answer 2

peristalsis.

is the alternating muscular contractions and relaxations that force the contents forward through the gastrointestinal tract.

Question 3

An example of a gastric secretion is

Answer 3

hydrochloric acid.

Gastric secretions work together to make chemical digestion possible. Five types of substances are involved, including enzymes, hydrochloric acid and buffer ions, mucus, water and electrolytes, and bile. In this case, hydrochloric acid is the gastric secretion.

Question 4

A pizza slice is being consumed by a hungry teen. The first actions of biting, chewing, and breaking up the slice into smaller particles is called

Answer 4

mastication.

begins mechanical digestion in the mouth. Mastication is the biting and chewing that begins to break food into smaller particles.

Question 5

A food that begins digestion in the mouth is

Answer 5

bread.

In the mouth, salivary glands secrete salivary amylase, which is the general name for any starch-splitting enzyme. Thus a food with starch content, such as bread, could begin its chemical digestion in the mouth.

Question 6

After a period of mixing and churning of the ingested food with the gastric secretions, the semifluid mass is called

Answer 6

chyme.

By the time the food mass reaches the lower portion of the stomach, it is a semiliquid, acid-food mix called chyme.

Question 7

The release of gastric secretions is stimulated by

Answer 7

nerves, hormones, and the presence of food in the stomach.

Gastric secretions are stimulated by nerves, hormones, and the presence of food in the stomach.

Question 8

One type of movement in the small intestine is

Answer 8

segmentation.

The intestinal muscles produce several types of movement that aid digestion, including peristaltic, pendular, segmental rings, longitudinal rotation, and surface villi motions.

Question 9

Compared with the pH in the stomach, the pH in the small intestine is

Answer 9

higher.

The pH of the stomach is acidic and the pH of the small intestine is alkaline.

Question 10

A meal of barbequed chicken, herbed rice, and green beans requires what enzyme to digest the chicken?

Answer 10

Peptidase

Carboxypeptidase, aminopeptidase, and dipeptidase are enzymes that break down protein to amino acids.

Question 11

A food that is ultimately broken down by trypsin is

Answer 11

chicken.

Trypsin breaks down protein to dipeptides. In this case, chicken is the protein food.

Question 12

The lining of the stomach and intestine is protected from strong acid by

Answer 12

mucus.

Large quantities of mucus are secreted by the intestinal glands to protect the mucosal lining from irritation and erosion caused by the high acidic gastric contents entering the duodenum. Because the stomach contains hydrochloric acid, mucus is available to protect its lining from the erosive effects of the acid.

Question 13

The hormone that stimulates the pancreas to release its secretions is

Answer 13

secretin.

The hormone secretin, which is produced by the mucosal glands in the first part of the intestine, controls the acidity and secretion of enzymes from the pancreas.

Question 14

A meal consisting of country fried steak, carrots, and a baked potato with butter and sour cream would stimulate the hormone cholecystokinin because of the

Answer 14

presence of fat in the duodenum.

The stimulus for the release of cholecystokinin is the present of fat in the duodenum. Once stimulated, cholecystokinin stimulates the gallbladder to release bile to emulsify fat.

Question 15

After eating a meal consisting of fried chicken, peas, and carrots, the end products of the digestion of fat from the fried chicken include

Answer 15

glycerol and fatty acids.

The end products of digestion of fats are glycerol and fatty acids. Intestinal lipase splits fat into glycerides and fatty acids.

Question 16

A means of absorption that occurs in the small intestine is

Answer 16

pinocytosis.

Simple diffusion, facilitated diffusion, active diffusion, and pinocytosis are the processes by which nutrients cross the inner intestinal wall and into the body circulation. Pinocytosis is the penetration of larger materials by attaching to the thicker cell membrane and being engulfed by the cell.

Question 17

After absorption, the end products of carbohydrate and protein digestion enter the

Answer 17

blood system.

Once carbohydrates and protein are digested and absorbed, they cross the inner intestinal wall and enter the bloodstream.

Question 18

The primary nutritional function of the large intestine is

Answer 18

absorption of water.

The primary function of the large intestine is to absorb water from the chyme. The water is absorbed in the first half of the colon.

Question 19

Bacteria found in the colon are significant because they

Answer 19

synthesize some vitamins.

Vitamin K is synthesized from bacteria in the large intestine.

Question 20

Gas formation in the colon is the result of

Answer 20

bacterial action on undigested items.

Bacterial action on indigestible food items in the large intestine can contribute to the formation of gas.

Question 21

After digestion, fatty materials are absorbed into the

Answer 21

lacteals.

Because fatty materials are not water soluble, these molecules pass into the lymph vessels in the villi (e.g., the lacteals), then into the larger lymph vessels of the body, and eventually into the bloodstream.

Question 22

Digestion of dietary fiber occurs in the

a. stomach.
b. small intestine.
c. large intestine.
d. none of the above.

Answer 22

none of the above.

Food fiber is not digested because human beings lack the specific enzymes required.

Question 23

The sum total of all the chemical changes that an organism performs to maintain its life and produce energy is the result of

Answer 23

metabolism.

Metabolism is the sum total of all chemical changes that take place in the body by which it maintains itself and produces energy for its functioning.

Question 24

Bile contains

Answer 24

emulsifiers.

Bile is an emulsifying agent that aids in fat digestion and absorption.

Question 25

Two organs that work with the small intestine in digestion are the

Answer 25

pancreas and liver.

The pancreas aids in digestion by secreting enzymes to aid in protein, carbohydrate, and fat digestion. As part of the hepatobiliary system, the presence of fat in the small intestine triggers the release of bile from the gallbladder.

Question 26

Conversion of amino acids to glucose is called

Answer 26

gluconeogenesis.

Question 27

The surface of the intestinal wall has mucosal folds, villi, and microvilli to

Answer 27

increase the surface area for absorption.

Mucosal folds, villi, and microvilli combine to make the inner surface some 600 times greater than the area of the outer surface of the intestine.

Question 28

Ways to minimize formation of stomach gas include

Answer 28

not gulping.

Stomach gas can be minimized by avoiding carbonated beverages, chewing with the mouth closed, not gulping food, not drinking from a can or through a straw, and not eating while nervous.

Question 29

A beverage that may cause intestinal gas in adults is

Answer 29

milk.

Many people lack the enzyme lactase to digest milk.