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321 - Physiology > Lecture 35 - Ruminant Carbohydrate Digestion and Absorption > Flashcards

Lecture 35 - Ruminant Carbohydrate Digestion and Absorption Flashcards

1
Q

is rumen contraction involuntary

A

yes, controlled by PNS and ENS

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2
Q

is reverse peristalsis involuntary

A

no, is controlled by skeletal muscle

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3
Q

how do herbivores live on plants

A

have microbes in rumen

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4
Q

what source of food do herbivores largely live on

A

lignocellulose

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5
Q

what is the most abundantly available raw material on earth to produce biofuels

A

lignocellulose

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6
Q

what is lignocellulose composed of

A

carbohydrate polymers: cellulose and hemicellulose
polymer: lignin

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7
Q

which component of lignocellulose is most abundant?

A

cellulose

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8
Q

which component of lignocellulose is hardly used by herbivores and microbes break down very slowly

A

lignin

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9
Q

what is cellulose composed of

A

unbranched, linear chains of D-glucose molecules linked together by beta (1-4) glycosidic bonds

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10
Q

structure of hemicellulose

A

main structure linked together by beta(1-4) glycosidic bonds with many branches

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11
Q

which is more structurally complex: cellulose or hemicellulose

A

hemicellulose

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12
Q

what allows herbivores to subsist on cellulose? by what mechanism?

A

microbes that produce cellulases that hydrolyze cellulose

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13
Q

which end product of fermentation do host animals particularly use?**

A

short chain volatile fatty acids

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14
Q

what bonds to cellulolytic bacteria break

A

beta 1-4 linkages between sugars that make up cellulose and hemicellulose

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15
Q

T/F: cellulolytic bacteria that can break beta 1-4 linkages in cellulose/hemicellulose are anaerobes

A

true!

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16
Q

how would you identify obligate aerobes in a test tube

A

need oxygen so gather at the top of the tube where oxygen concentration is highest

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17
Q

where would you find obligate anaerobes in a test tube

A

are poisoned by oxygen so would find them at the bottom of the tube where O2 concentration is lowest

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18
Q

where would you find facultative anaerobes in a test tube

A

can grow with or without oxygen because they can metabolize energy aerobically or anaerobically. Gather mostly at the top because aerobic respiration generates more ATP than fermentation

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19
Q

what do yogurt making bacteria and RBCs have in common

A

dont have mitochondria

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20
Q

what does glycolysis generate ***

A

generates 2 pyruvate and 2 ATP

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21
Q

what are the 2 main processes of lactic acid fermentation

A

Glycolysis and NAD+ regeneration

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22
Q

what is the end result of lactic acid fermentation

A

2 lactate

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23
Q

what is fermentation? what does it produce?

A

process of metabolism where an organism converts carbohydrate (sugar/ starch) into an alcohol or acid. it produces energy in the absence of oxygen

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24
Q

how many ATP does aerobic respiration produce

A

36 ATP

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25
Q

what kind of environment does the rumen provide (02, temp, etc)

A

anaerobic environment, constant temperature and good mixing

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26
Q

describe the relationship of fermentative microbes in the rumen

A

interact and support eachother in a food web (waste products of one can be nutrients for other species), can compliment eachother

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27
Q

amylolytic microbes digest

A

starch

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28
Q

proteolytic microbes digest

A

protein

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29
Q

starch utilizing bacteria use what

A

mono and disaccharides

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30
Q

acid utilizing microbes use what

A

substrates like lactic, succinic and malic acids

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31
Q

are ammonia producers, vitamin synthesizers and methane producing microbes common in the rumen

A

yes

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32
Q

what do cellulolytic bacteria break and use***

A

beta1-4 linkages of plant wall structural carbohydrates and utilize liberated hexose and pentoses for energy

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33
Q

end product of cellulolytic bacteria***

A

are anaerobes so end product of fermentation is VFAs acetic acid, propionic acid and butyric acid

34
Q

what is the end END product of glycolysis***

A

glycolysis produces pyruvate and THEN pyruvate further produces volatile fatty acids: acetate, butyrate and propionate

35
Q

what is the source for host animals to generate energy

A

volatile fatty acids: acetate, butyrate, propionate

36
Q

what 3 volatile fatty acids does pyruvate break down into to generate energy for the host animal ***

A

acetate, butyrate, propionate

37
Q

what provides majority of herbivore energy

A

volatile fatty acids

38
Q

Major VFA product in diet is always**

A

acetic acid

39
Q

will sugar molecules from the diet be absorbed by the small intestine of a cow

A

no, will be used by microbes

40
Q

what is oxidized throughout most of the body to generate ATP in ruminants

A

Acetic acid

41
Q

what is another important use of acetate besides generating ATP in ruminants

A

major source for synthesis of lipids

42
Q

***acetic acid is the _____ form of acetate

A

undissociated form

43
Q

*** acetate is the _______ form of acetic acid

A

dissociated

44
Q

**acetic acid dissociates in water to become ______

A

acetate

45
Q

which is dissociated: acetic acid or acetate

A

acetate

46
Q

which is undissociated: acetic acid or acetate

A

acetic acid

47
Q

what is the major substrate for gluconeogenesis in the liver

A

proprionic acid

48
Q

function of proprionic acid

A

major substrate for gluconeogenesis in liver

49
Q

why is gluconeogenesis crutial in ruminants

A

almost no glucose reaches the small intestine for absorption

50
Q

what is gluconeogenesis

A

formation of glucose from non-carbohydrate carbon sources

51
Q

what is the function of butyric acid***

A

oxidized in many tissues for ATP (energy production)

52
Q

how is fat synthesized

A

from ruminal acetic acid

53
Q

what epithelium are the rumen and reticulum lined by

A

stratified squamous epithelium

54
Q

where are VFAs rapidly absorbed

A

across the forestomach (even though it is stratified squamous epithelium) and leaves of the omasum via diffusion –> then are used by ruminant for energy

55
Q

in their non-dissociated state, are VFAs water AND lipid soluble

A

yes, have no charge and can cross the lipid bilayer of cell membranes

56
Q

are VFAS in their dissociated state both lipid and water soluble

A

NO, are only water soluble and CANNOT cross lipid membranes, remember this is for dissociated state (ex. acetate)

57
Q

dissociated and non dissociated forms of weak acids and bases are in ______

A

equilibrium

58
Q

what is the concentration of nondissociated and dissociated forms dependent on

A

the pH of solution

59
Q

describe the importance of pKa in the relationship between acids existing in their dissociated vs non dissociated state

A

when the pKa is = to pH of solution, 50% of the acid will exist in its dissociated state and 50% in its non dissociated state (aka. at =librium)

60
Q

given that the pKa for propionic acid is 4.87, and its in a solution with pH 4.8. how much is in the dissociated state vs nondissociated

A

50% will exist in non-dissociated state (Hporp) while 50% is in the dissociated state (prop-)

61
Q

given that the pKa of propionic acid is 4.87, at typical rumen pH, what amount of propionic acid is in its non dissociated form vs dissociated form

A

rumen pH (6-7 according to miss google) is higher than the pKa of propionic acid, so majority is in the dissociated form while only a small percentage is in the non dissociated form.

62
Q

what happens to the small amount of non dissociated propionic acid (Hprop) in the lumen of the rumen? (aka, how does it travel from lumen of rumen to extracellular fluid)

A

will freely cross the apical membrane down its concentration gradient from the lumen to the apical/interior of the cell, becuase Hprop is removed from the lumen, the =libirum of propionic acid will shift to replace the lost Hprop, allowing more to cross the membrane

Once of the other side of the membrane, a second propionic equilibrium is set up near the basolateral surf, as Hprop is formed, it will move across the basolateral membrane to the extracellular fluid

63
Q

the amount of propionic acid existing in the dissociated vs non-dissociated state is dependent on what?

A

pKa of the acid and the pH of solution

64
Q

what is the mechanism that alllows all VFAs to cross membranes

A

diffusion through the epithelium down a concentration gradient

65
Q

where does venus blood from the fore-stomach and abomasum drain into

A

portal vein to the liver

66
Q

VFA purposes

A

energy production, production of sugars and lipids, etc..

67
Q

what is rumen-degradable protein***

A

dietary protein that the rumen can break down***

68
Q

how is rumen degradable protein lost to the animal and then potentially recovered?

A

are used by microbes so lost to the animal but can be recovered in the form of microbial protein that enters the small intestine

69
Q

rumen undigestible protein***

A

protein that bypasses the rumen bacteria, can be digested in the small intestine and a source of essential amino acids

70
Q

protein quality

A

ability of dietary protein to meet the needs for regular metabolism and maintenance or growth of body tissues

71
Q

protein quality factors

A

digestibility and quantity of essential amino acids

72
Q

essential amino acids

A

cannot be made by the body, must come from food

73
Q

is rumen bacteria high quality protein

A

yeso

74
Q

how is protein within bacteria digested

A

mammalian proteolytic enzymes

75
Q

how much microbial protein acounts for total protein digested in cattle

A

more than 50%

76
Q

what non-protein nitrogen source can fermentative microbes synthesize protein from

A

urea (used for inexpensive diets)

77
Q

what vitamins are fermentative microbes able to synthesize

A

B vitamins

78
Q

describe the path of crude protein from feed for the cow to nutrients in the cow (undegradable intake protein vs. degradable intake protein)

A

Undegradable: starts as crude protein in feed, bypasses fermentation adn goes to the stomach to become amino acids)

degradable: starts as crude protein in feed, is taken by microbes to contribute to growtih and fermentation, then becomes microbial protein and then broken down into aa)

79
Q

what component of feed is fermented in the rumen to become propionic

A

starch and sugar

80
Q

what component of feed is fermented to become acetic and butyric?

A

fermentable fiber

81
Q

what component of feed gets fermented in the rumen to become fatty acids

A

fat

82
Q

compare protein processing in simple stomach species vs ruminants

A

in simple stomach: HCL and pepsin in the stomach

ruminants: microbes feed on protein in the forestomach and then are broken down by HCL and pepsin in the true stomach afterwards

321 - Physiology (52 decks)

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