Chapter 17: Digestive Physiology

Question 1

6 classes of nutrients

Answer 1

carbohydrates
proteins
fats
vitamins
minerals
water

Question 2

what are the major nutrients?

Answer 2

carbs
proteins
fats

Question 3

what do major nutrients provide?

Answer 3

• building blocks used to produce cellular structures such as plasma membranes, collagen, muscle proteins, and myelin sheaths
• provide energy (cells break them down and use the energy in their chemical bonds to produce ATP)

Question 4

function of vitamins

Answer 4

function as coenzymes
- they act with an enzyme to accomplish a particular chemical reaction

Question 5

function of minerals

Answer 5

-they are ionized in the body fluids or attached to organic compounds and they are essential for binding oxygen, nerve impulse production, muscle contraction

Question 6

function of water

Answer 6

• dissolving medium
• all chemical reactions occurring in the body depend on water’s solvent properties
• water is a reactant in some metabolic processes

Question 7

to be be used by the body nutrients must undergo some processes. what are they?

Answer 7

• ingestion
• propulsion
• mechanical breakdown
• digestion
• absorption
• defecation

Question 8

ingestion

Answer 8

taking food into the digestive tract via the mouth

Question 9

propulsion

Answer 9

moves food through the digestive tract

-includes deglutition (chewing) and peristalsis

Question 10

mechanical breakdown

Answer 10

increases surface area of ingested food physically preparing it for digestion by enzymes

Question 11

what are the mechanical breakdown processes

Answer 11

mastication
mixing food with saliva by the tongue
churning food in the stomach
segmentation (rhythmic contractions of the small intestine that mix food with enzymes and other digestive secretions)

Question 12

segmentation

Answer 12

rhythmic contractions of the small intestine that mix food with enzymes and other digestive secretions

Question 13

digestion

Answer 13

process in which complex molecules are chemically broken down into simpler molecules

Question 14

hydrolysis

Answer 14

breaks down the major nutrients into their basic units by adding water molecules at the bond sites

Question 15

monosaccharides

Answer 15

the basic units of carbohydrates

Question 16

amino acids

Answer 16

the basic unit of a protein

Question 17

true or false: fats are very diverse and do not have a defined basic unit

Answer 17

true

Question 18

most dietary fats are triglycerides which are digested into ____ and _____.

Answer 18

fatty acids and glycerol

Question 19

hydrolysis is catalyzed by ____.

Answer 19

enzymes

Question 20

a substance upon which an enzyme acts thereby causing that substance to undergo a chemical reaction is the ______ of that enzyme.

Answer 20

substrate

Question 21

to catalyze a reaction, an enzyme must :

Answer 21

temporarily bind to a substrate

Question 22

denaturing

Answer 22

the shape of an enzyme changes

Question 23

most enzymes and other proteins are denatured by :

Answer 23

high temperatures and changes in pH

Question 24

absorption

Answer 24

the movement of nutrients in the tracts lumen through the epithelium into blood or lymph capillaries in the lamina propria of the tracts mucosa

Question 25

defecation

Answer 25

eliminates indigestible substances and any unabsorbed nutrients from the body via the anus in the form of feces

Question 26

vitamins, minerals, and water must undergo _____, ____, ____.

Answer 26

ingestion
propulsion
absorption

Question 27

indigestible materials and any nutrients that are not absorbed undergo _____.

Answer 27

defecation

Question 28

which classes of nutrients must be digested into simpler molecules before they can be absorbed?

Answer 28

carbs, proteins, fats

Question 29

in digestion, bonds are broken by adding _____ at the bind sites.

Answer 29

water: (this is hydrolysis)

Question 30

polypeptides

Answer 30

long chains of amino acids

Question 31

pepsin

Answer 31

protein digesting enzyme (protease)

Question 32

the stomach secretes _____ and ____ into its lumen, where _____ converts ______ into active pepsin.

Answer 32

the stomach secretes pepsinogen (an inactive form of pepsin) and hydrochloric acid into its lumen where HCL converts pepsinogen into ACTIVE pepsin

Question 33

what is a protease?

Answer 33

protein digesting enzyme

Question 34

what is the substrate of pepsin?

Answer 34

hydrochloric acid (HCl)

Question 35

digestion is considered to have occurred only if a piece of egg white or potato is quite a bit smaller than that in tube 1 or 6. explain why a slight change in size is not an indication that digestion occurred.

Answer 35

because it just mushes it by dissolving it a tiny bit

Question 36

is the presence of pepsin necessary for protein digestion to occur? support your answer using experinebtal results

Answer 36

yes; because we compared it to test tube 2 and 3 which had the same temp, the only difference was pepsin was in one and dH2O was in the other. the pepsin tube digested it the other did not

Question 37

does the pH of a test tube affect the activity of the pepsin?

Answer 37

yes; when we compare test tube 2 which had a pH of 1 to test tube 4 that had a pH of 8 the more acidic one digested it

Question 38

pepsin catalyzes the digestion of a _______. support your answer

Answer 38

protein: the potato with pepsin did not digest but the egg white did

Question 39

HCl makes the stomach contents:

Answer 39

extremely acidic

Question 40

most ____ function as coenzymes.

Answer 40

vitamins

Question 41

water is a ______, ______, and ______.

Answer 41

dissolving medium
solvent
reactant