Topic 5.1: Digestion

Question 1

List the parts of the human digestive tract that food passes through, and note whether chemical and/ or mechanical digestion occurs.

Answer 1

Mouth-Mechanical and chemical
Pharynx- No aid in digestion
Esophagus- No aid in digestion
Stomach- Mechanical and chemical
Small intestine- Chemical
Large intestine- Small amount of chemical by bacteria

Question 2

Compare the major functions of the small intestine and the large intestine.

Answer 2

The small intestine processes food for digestion and absorbs nutrients. Its lower part, the ileum, is involved in immune responses.

The large intestine absorbs water, salts, and some vitamins, and eliminates indigestible material as feces.

Question 3

Discuss strategies that might help obese people lose weight by inhibiting the secretion and/or activity of certain hormones.

Answer 3

Hormones that increase digestive activity include gastrin, secretin, and CCK. Inhibiting these might regulate weight but they can cause difficulties in digesting food, leading to excess gas or constipation.

Question 4

Define digestive system

Answer 4

Organ system that consists of digestive organs (stomach, intestines, etc.) and accessory organs (liver, etc.); ingests and digests food; absorbs nutrients and eliminates wastes.

Question 5

Define mouth

Answer 5

In humans, organ of the digestive tract where food is chewed and mixed with saliva.

Question 6

Define salivary glands

Answer 6

In humans, gland associated with the mouth, that secretes saliva.

Question 7

Define pharynx

Answer 7

In vertebrates, common passageway for both food intake and air movement; located between the mouth and the esophagus.

Question 8

Define esophagus

Answer 8

Muscular tube for moving swallowed food from the pharynx to the stomach.

Question 9

Define peristalsis

Answer 9

Wavelike contractions that propel substances along a tubular structure such as the esophagus.

Question 10

Define lumen

Answer 10

Cavity inside any tubular structure, such as the lumen of the digestive tract.

Question 11

Define stomach

Answer 11

In vertebrates, muscular sac that mixes food with gastric juices to form chyme, which enters the small intestine.

Question 12

Define chyme

Answer 12

Thick, semiliquid food material that passes from the stomach to the small intestine.

Question 13

Define small intestine

Answer 13

In vertebrates, the portion of the digestive tract that precedes the large intestine. In humans, consists of the duodenum, jejunum, and ileum.

Question 14

Define duodenum

Answer 14

First part of the small intestine, where chyme enters from the stomach.

Question 15

Define jejunum

Answer 15

Region of the small intestine located between the duodenum and ileum.

Question 16

Define ileum

Answer 16

Region of the small intestine; connects the jejunum and large intestine.

Question 17

Define villus

Answer 17

Small, fingerlike projection of the inner small intestinal wall.

Question 18

Define lacteal

Answer 18

Lymphatic vessel in an intestinal villus; aids in the absorption of fats.

Question 19

Define large intestine

Answer 19

In vertebrates, portion of the digestive tract that follows the small intestine. In humans, consists of the cecum, colon, rectum, and anal canal.

Question 20

Define cecum

Answer 20

Region of the large intestine, just below the small intestine, to which the appendix is attached.

Question 21

Define appendix (vermiform appendix)

Answer 21

In humans, small, tubular appendage that extends outward from the cecum of the large intestine.

Question 22

Define vestigial structure

Answer 22

Remnant of a structure that was functional in some ancestor but is no longer functional in the organism in question.

Question 23

Define anus

Answer 23

Outlet of the digestive tube.

Question 24

Define fiber

Answer 24

General term for indigestible plant material, typically complex carbohydrates such as cellulose.

Question 25

Review what it means to say that the pancreas has both endocrine and exocrine functions.

Answer 25

The pancreas secretes hormones (endocrine) such as insulin and glucagon into the blood, and also secretes digestive enzymes (exocrine) into the small intestine by way of ducts.

Question 26

List what each accessory gland contributes to the process of digestion.

Answer 26

Salivary glands produce saliva, which moistens food and contains amylase, which begins the digestion of starch.

The liver detoxifies blood by removing and metabolizing poisonous substances, stores iron and vitamins A, D, E, K and B12, makes many plasma proteins, such as albumins and fibrinogen, from amino acids, stores glucose and glycogen after a meal, and breaks down glycogen to glucose to maintain the glucose concentration of blood between eating periods, produces urea after breaking down amino acids, removes bilirubin, a breakdown products oof hemoglobin from the blood, and excretes in in bile, a liver product, and helps regulate blood cholesterol level, converting some bile salts.

The main function of the gallbladder is to store bile. The pancreas secretes bicarbonate, digestive enzymes, and the hormones insulin and glucagon.

Question 27

Explain why the liver is necessary for life, whereas the gallbladder can be removed with few consequences.

Answer 27

The gallbladder stores bile and people can live without this function. The liver has essential functions of detoxification, storage, synthesis, lipid regulation, and hemoglobin breakdown, all of which are necessary for survival.

Question 28

Define liver

Answer 28

Large, dark red internal organ that produces urea and bile, detoxifies the blood, stores glycogen, and produces the plasma proteins, among other functions.

Question 29

Define bile

Answer 29

Secretion of the liver that is temporarily stored and concentrated in the gallbladder before being released into the small intestine, where it emulsifies fat.

Question 30

Define pancreas

Answer 30

Internal organ that produces digestive enzymes and the hormones insulin and glucagon.

Question 31

Define gallbladder

Answer 31

Organ attached to the liver that serves to store and concentrate bile.

Question 31

Define gallbladder

Answer 31

Organ attached to the liver that serves to store and concentrate bile.

Question 32

Define gallbladder

Answer 32

Organ attached to the liver that serves to store and concentrate bile.

Question 33

Describe where in the digestive tract the chemical digestion of each of the following types of nutrients occurs: carbohydrates, proteins, and fats.

Answer 33

Carbohydrate digestion begins in the moth, with salivary amylase, and continues in the small intestine, due to maltase and pancreatic amylase.

Protein digestion begins in the stomach, where pepsin breaks proteins into peptides, and continues with trypsin and peptidases in the small intestine.

Fats are mainly digested by pancreatic lipase in the small intestine.

Question 34

Identify the final molecule (monomer) resulting from the digestion of carbohydrates, proteins, and fats.

Answer 34

Carbohydrates are broken down to glucose; proteins to amino acids; fats to glycerol and fatty acids.

Question 35

Explain how the structure of the digestive system assists in regulating the digestive enzymes.

Answer 35

The digestive system is divided into many compartments, each of which has a distinctive internal environment and pH. These differences contribute to regulation of digestive enzymes.

Question 36

Define salivary amylase

Answer 36

In humans, enzyme in saliva that digests starch to maltose.

Question 37

Define pepsin

Answer 37

Enzyme secreted by gastric glands that digests proteins to peptides.

Question 38

Define pancreatic amylase

Answer 38

Enzyme that digests starch to maltose.

Question 39

Define trypsin

Answer 39

Protein-digesting enzyme secreted by the pancreas.

Question 40

Define lipase

Answer 40

Fat-digesting enzyme secreted by the pancreas.

Question 41

Define peptidase

Answer 41

Intestinal enzyme that breaks down short chains of amino acids to individual amino acids that are absorbed across the intestinal wall.

Question 42

Define maltase

Answer 42

Enzyme produced in small intestine that breaks down maltose to two glucose molecules.

Question 43

The digestive system consists of a series of tissues surrounding a hollow space called the
a) serosa
b) mucosa
c) lumen
d) muscularis

Answer 43

c) lumen

Question 44

The large intestine
a) digests all types of food
b) is the longest part of the intestinal tract
c) absorbs water
d) is connected to the stomach
e) is subject to hepatitis

Answer 44

a) digests all types of food

Question 45

This organ may be part of the immune system and helps prevent infections in the large intestine.
a) duodenum
b) rectum
c) cecum
d) appendix

Answer 45

d) appendix

Question 46

This structure blocks the opening to the respiratory system during swallowing.
a) esophagus
b) pharynx
c) epiglottis
d) salivary gland

Answer 46

c) epiglottis

Question 47

Which of the following is incorrect regarding gastric juice?
a) it is provided by the pancreas
b) it contains pepsin to digest protein
c) it has a pH of 2 due to hydrochloric acid
d) it is produced by the gastric glands

Answer 47

a) it is provided by the pancreas

Question 48

Bile
a) is an important enzyme for the digestion of fats
b) cannot be stored
d) emulsifies fat
e) all of these are correct

Answer 48

d) emulsifies fat

Question 49

Which of the following is not a function of the liver in adults?
a) produces bile
b) detoxifies alcohol
c) stores glucose
d) produces urea
e) makes red blood cells

Answer 49

e) makes red blood cells

Question 50

What is the exocrine function of the pancreas?
a) secrete insulin and glucagon
b) make plasma proteins
c) produce sodium bicarbonate and digestive enzymes
d) convert cholesterol into bile salts

Answer 50

a) secrete insulin and glucagon

Question 51

Which of these could be absorbed directly without need of digestion?
a) glucose
b) nucleic acid
c) fat
d) protein
e) all of the above

Answer 51

a) glucose

Question 52

Which association is incorrect?
a) protein- trypsin
b) fat-lipase
c) maltose-pepsin
d) starch- amylase
e) protein-pepsin

Answer 52

c) maltose-pepsin

Question 53

Which of the following nutrients are loaded into chylomicrons and transported by the lymphatic system following digestion?
a) carbohydrates
b) fats
c) proteins
d) none of the above

Answer 53

d) none of the above