digestion - exam 2

Question 1

how can simple animals have direct exchange w/ the environment

Answer 1

thin, flat shape

very few cell layers

live in moist environments

Question 2

specialized exchange surfaces for complex animals

Answer 2

composed of living cells

thin

large surface area – folds & branches

moist – intersitital fluid

external or internal

connected to circulatory system

Question 3

herbivore teeth

Answer 3

ridges & grooves good for grinding up the cellulose in plants

Question 4

carnivore teeth

Answer 4

sharp to rip flesh

Question 5

digestive tract

Answer 5

mouth –> esophagus –> stomach –> small intestine –> large intestine –> rectum –> anus

Question 6

mechanical digestion in mouth

Answer 6

physical breaking down of food

use teeth to chew – bolus

Question 7

chemical digestion in mouth

Answer 7

using enzymes to break down food

Question 8

salivary amylase

Answer 8

breaks down starch

Question 9

mucus

Answer 9

coats bolus & helps it slip down the esophagus

Question 10

antibacterial agents

Answer 10

makes sure we don’t get sick from bacteria on food

Question 11

mechanical digestion in stomach

Answer 11

peristalsis / churning

Question 12

chemical digestion in stomach

Answer 12

gastric juice digests proteins

Question 13

Hydrochloride acid

Answer 13

pH 2

kills bacteria

denatures proteins

activates protease

Question 14

pepsin

Answer 14

protease

enzyme that breaks down proteins

can activate pepsinogen

Question 15

why don’t pepsin & HCl damage cells that make them

Answer 15

they make inactive forms & release them into the lumen - where they are activated

Question 16

chief cell

Answer 16

makes pepsinogen

Question 17

pepsinogen

Answer 17

inactive form of pepsin

Question 18

parietal cell

Answer 18

HCl

activates pepsinogen

Question 19

why aren’t cells lining stomach damaged by pepsin & HCl

Answer 19

gastric juices not released until food arrives in stomach

mucus cells secrete protective mucus

rapid mitosis – the cells do get destroyed by HCl but they are replaced very quickly

Question 20

chemical digestion in the small intestine

Answer 20

takes place in the duodenum

aided by accessory organs

pH = ~7.5

Question 21

pancreatic amylase

Answer 21

breaks down carbs during chemical digestion in small intestine

Question 22

pancreatic proteases

Answer 22

break down proteins during chemical digestion in small intestine

trypsin & chymotrypsin

Question 23

trypsin & chymotrypsin

Answer 23

secreted as inactive precursors -
trypsinogen & chymotrypsinogen

activated in the small intestine - in the wall of the duodenum

Question 24

pancreatic nucleases

Answer 24

break down nucleic acids during chemical digestion in small intestine

Question 25

pancreatic lipase

Answer 25

break down fats during chemical digestion in small intestine fats in hydrophobic globules

Question 26

mechanical digestion in small intestine

Answer 26

bile emulsifies fats breaks them into smaller fat globules that give lipase a larger surface area to break them down

Question 27

bile

Answer 27

made in the liver stored in the gall bladder

Question 28

where does absorption occur

Answer 28

across the small intestine folds provide more surface area

Question 29

large circular folds

Answer 29

increase the surface area for more efficient absorption

Question 30

villi

Answer 30

smaller folds on the large circular folds lined w/ epithelial tissue vessels & lacteal

Question 31

microvilli

Answer 31

villi on the epithelial cells of the villi

Question 32

where do the breakdown products of carbs, proteins, & nucleic acids go

Answer 32

directly into the bloodstream

Question 33

where do the breakdown products of fats go

Answer 33

epithelial cell where triglycerides get put back together to form a chylomicron

Question 34

chylomicron

Answer 34

contains triglycerides type of lipo protein complex moves into the lacteal then the liver then the bloodstream

Question 35

role of large intenstine

Answer 35

reabsorption of water water/undigested material (feces) becomes more solid feces eliminated from the body

Question 36

plant eater digestive system

Answer 36

longer small intestines large cecum

Question 37

benefit of longer small intestine for plant eaters

Answer 37

more time for chemical digestion more time for absorption to occur

Question 38

cecum

Answer 38

anaerobic (no oxygen) chamber cellulose digestion microbes live there

Question 39

rumen

Answer 39

anaerobic chamber w/ cellulose digestion microbes

Question 40

rumen in cows

Answer 40

digests grass into rumen rumen regurgitates it back into the mouth more mechanical digestion digests it for real

Question 41

homeostasis

Answer 41

maintenance of internal balance despite external factors

Question 42

positive feedback

Answer 42

the products of a reaction leads to an increase in that reaction moves system away from homeostasis child birth

Question 43

negative feedback

Answer 43

a control mechanism that "dampens" a stimulus

Question 44

hormone

Answer 44

chemical messenger released into bloodstream that acts on distant target cells hormone = signal in the signal transduction pathway

Question 45

what happens if glucose is too high

Answer 45

beta cells in pancreas release insulin into the blood it binds to receptor in a body cell -- signal transduction blood glucose level declines & returns to homeostasis

Question 46

what happens if glucose is too low

Answer 46

alpha cells of pancreas release glucagon into blood it binds to liver cell liver stores glycogen so it releases some back into the blood stream blood glucose level rises & returns to homeostasis

Question 47

leptin

Answer 47

appetite-suppressing hormone secreted by adipose (fat) cells

Question 48

leptin w/ weight gain

Answer 48

gain weight more leptin secreted = decreased food intake (less appetite) increased metabolic rate returns to "homeostatic" size

Question 49

leptin w/ weight loss

Answer 49

lose weight less leptin secreted = increased food intake (more appetite) decreased metabolic rate returns to "homeostatic" state