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BIOLOGY > digestion - exam 2 > Flashcards

digestion - exam 2 Flashcards

1
Q

how can simple animals have direct exchange w/ the environment

A

thin, flat shape

very few cell layers

live in moist environments

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2
Q

specialized exchange surfaces for complex animals

A

composed of living cells

thin

large surface area – folds & branches

moist – intersitital fluid

external or internal

connected to circulatory system

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3
Q

herbivore teeth

A

ridges & grooves good for grinding up the cellulose in plants

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4
Q

carnivore teeth

A

sharp to rip flesh

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5
Q

digestive tract

A

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

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6
Q

mechanical digestion in mouth

A

physical breaking down of food

use teeth to chew – bolus

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7
Q

chemical digestion in mouth

A

using enzymes to break down food

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8
Q

salivary amylase

A

breaks down starch

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9
Q

mucus

A

coats bolus & helps it slip down the esophagus

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10
Q

antibacterial agents

A

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

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11
Q

mechanical digestion in stomach

A

peristalsis / churning

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12
Q

chemical digestion in stomach

A

gastric juice digests proteins

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13
Q

Hydrochloride acid

A

pH 2

kills bacteria

denatures proteins

activates protease

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14
Q

pepsin

A

protease

enzyme that breaks down proteins

can activate pepsinogen

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15
Q

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

A

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

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16
Q

chief cell

A

makes pepsinogen

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17
Q

pepsinogen

A

inactive form of pepsin

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18
Q

parietal cell

A

HCl

activates pepsinogen

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19
Q

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

A

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

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20
Q

chemical digestion in the small intestine

A

takes place in the duodenum

aided by accessory organs

pH = ~7.5

21
Q

pancreatic amylase

A

breaks down carbs during chemical digestion in small intestine

22
Q

pancreatic proteases

A

break down proteins during chemical digestion in small intestine

trypsin & chymotrypsin

23
Q

trypsin & chymotrypsin

A

secreted as inactive precursors -
trypsinogen & chymotrypsinogen

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

24
Q

pancreatic nucleases

A

break down nucleic acids during chemical digestion in small intestine

25
Q

pancreatic lipase

A

break down fats during chemical digestion in small intestine

fats in hydrophobic globules

26
Q

mechanical digestion in small intestine

A

bile emulsifies fats

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

27
Q

bile

A

made in the liver

stored in the gall bladder

28
Q

where does absorption occur

A

across the small intestine

folds provide more surface area

29
Q

large circular folds

A

increase the surface area for more efficient absorption

30
Q

villi

A

smaller folds on the large circular folds

lined w/ epithelial tissue

vessels & lacteal

31
Q

microvilli

A

villi on the epithelial cells of the villi

32
Q

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

A

directly into the bloodstream

33
Q

where do the breakdown products of fats go

A

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

34
Q

chylomicron

A

contains triglycerides

type of lipo protein complex

moves into the lacteal
then the liver
then the bloodstream

35
Q

role of large intenstine

A

reabsorption of water

water/undigested material (feces) becomes more solid

feces eliminated from the body

36
Q

plant eater digestive system

A

longer small intestines

large cecum

37
Q

benefit of longer small intestine for plant eaters

A

more time for chemical digestion

more time for absorption to occur

38
Q

cecum

A

anaerobic (no oxygen) chamber

cellulose digestion microbes live there

39
Q

rumen

A

anaerobic chamber w/ cellulose digestion microbes

40
Q

rumen in cows

A

digests grass into rumen

rumen regurgitates it back into the mouth

more mechanical digestion

digests it for real

41
Q

homeostasis

A

maintenance of internal balance despite external factors

42
Q

positive feedback

A

the products of a reaction leads to an increase in that reaction

moves system away from homeostasis

child birth

43
Q

negative feedback

A

a control mechanism that “dampens” a stimulus

44
Q

hormone

A

chemical messenger released into bloodstream that acts on distant target cells

hormone = signal in the signal transduction pathway

45
Q

what happens if glucose is too high

A

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

46
Q

what happens if glucose is too low

A

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

47
Q

leptin

A

appetite-suppressing hormone secreted by adipose (fat) cells

48
Q

leptin w/ weight gain

A

gain weight

more leptin secreted =
decreased food intake (less appetite)
increased metabolic rate

returns to “homeostatic” size

49
Q

leptin w/ weight loss

A

lose weight

less leptin secreted =
increased food intake (more appetite)
decreased metabolic rate

returns to “homeostatic” state

BIOLOGY (31 decks)

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