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Nutr 4210 > 4+5. integrative metabolism carbohydrates > Flashcards

4+5. integrative metabolism carbohydrates Flashcards

1
Q

plasma-derived substrates

A

glucose and fatty acids

- supply most energy at low intensities

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2
Q

endogenous substrates

A

glycogen and triglycerides

  • more important at higher intensities
  • 65% vo2 max
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3
Q

later stages of exercise

- source of energy

A

plasma source of substrate more important

- endogenous sources decline

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4
Q

higher intensities of exercise

A

endogenous more important

- CHO

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5
Q

longer duration of exercise

A

plasma-derived substrates more important

- FFAs

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6
Q

blood glucose concentration regulation

- maintenence value

A

hepatic glucose production (HGP)

  • approx 4-5mM
  • tighter compared to FFA (0.2-2mM)
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7
Q

tissues that depend on glucose

A

neural
- can also use ketone bodies
red blood cells
- lack mitochondria

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8
Q

maximum leg glucose uptake

- problem (total blood glucose content)

A

~ 2 mM/min

  • total blood gluc content only 20mM
  • theoretically depleted in 10min
  • liver compensates
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9
Q

glycogen bonds

A

straight
- alpha 1,4 bonds

branching
- alpha 1,6 bonds

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10
Q

enzymes that breakdown glycogen

- pathway and substrate produced

A

glycogen phosphorylase
- alpha 1,4 bonds

debranching enzyme
- alpha 1,6 bonds

*glycogenolysis produces G6P (glucose-6-phosphate)

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11
Q

G6P in “liver” during exercise

A

converted to glucose

- exported to systemic circulation

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12
Q

G6P in “muscle” during exercise

A

used for anaerobic and aerobic metabolism for the muscle

  • glycolysis
  • converted to pyruvate

*can NOT be converted to glucose

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13
Q

glycogen utilization

- rate of depletion fasting during

A

onset of exercise

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14
Q

glycogen utilization curve

  • duration
  • intensity
A

exponential curves

  • decline with time
  • incline with intensity
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15
Q

liver glycogen utilization

- how quickly can it be used in 1hr

A

can utilize 50% in 1hr

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16
Q

glycogen sparing definition

- what improves it

A

reduced rate of glycogen utilization at “initial period” of exercise
- improved with aerobic training and lipid availability

17
Q

liver gluconeogenesis with exercise

  • increasing intensity
  • recovery**
A

decline gluconeogenesis with increased intensity

  • stop exercising, hepatic blood flow rapidly restored
  • gluconeogenic precursors still high concentration in blood
  • huge “spike” in gluconeogenesis results
18
Q

liver glycogenolysis and gluconeogenesis with increasing intensities

A

glycogenolysis (% of blood glucose contribution)

  • rest 65-75%
  • increase with intensity up to 85-94%
  • recovery huge decline 30-60%

*gluconeogenesis huge contribution during recovery

19
Q

gluconeogenesis (GNG) defn

- substrates

A

glucose synthesis from non-carbohydrate sources

  • pyruvate
  • lactate
  • glycerol
  • some AAs

*muscle does NOT have enzymes for GNG

20
Q

gluconeogenesis pathway

  • starting substrates
  • intermediates
A 
start
- pyruvate (cytosol)
- lactate
- aminos
intermediates
- glycerol
- oxaloacetate (mitochondria)
21
Q

regulation of gluconeogenesis by cAMP

A

cAMP simultaneously increases GNG and decreases glycolysis

promotes

  • pyruvate carboxylase (pyruvate to oxaloacetate)
  • fructose 1,6 biphosphatase (F 1,6-P to F 6-P)

inhibits

  • pyruvate kinase (PEP to pyruvate)
  • phosphofructokinase PFK ( F 6-P to F 1,6-P)
22
Q

glycolysis produced

A

pyruvate

23
Q

anaerobic pathway of pyruvate

A

anaerrobic “reduction”

  • lactate dehydrogenase (LDH)
  • lactic acid
  • lactate + H ion
24
Q

aerobic pathway of pyruvate

A

aerboic “oxidation”

  • pyruvate dehydrogenase (PDH)
  • acetyl coA (mitochondria)
  • citric acid cycle
25
Q

formation of ATP from pyruvate

A

substrate level phosphorylation

26
Q

lactic acid when at pH of 7

A

in lactate form

27
Q

importance of lactate production

A

produces NAD+ when oxygen in short supply

- allows glycolysis to continue

28
Q

fate of lactate

A

high levels

  • moves from muscle to blood
  • liver and heart uptake
  • can be used aerobically to produce ATP
  • in liver also used in GNG (cori cycle**)
29
Q

cori cycle

A

liver GNG

  • 2 lactate –> 2 pyruvate –> glucose
  • costs 6 atp
30
Q

what is the cause of muscle soreness

A

delayed muscle soreness (DOMS)
- inflammatory repair response in muscle

*not lactic acid buildup

31
Q

lactate threshold (LT)

A

level of exercise intensity when lactate production exceeds removal from blood
- sharp blood lactate increase

training accelerates lactate clearance

32
Q

effect of glucose transport with exercise

A

rapid increase

- persists several hours after post exercise

33
Q

glucose transport can be stimulated by 2 seperate pathways in skeletal muscle
- activated by?

A

activated by

  1. insulin
  2. contractile activity

additive affect

34
Q

how insulin and contractile activity effect glucose transport

A

move GLUT4 receptor to plasma membrane
- distinct pathways

insulin

  • binds receptor
  • IRS –> PI 3-kinase and so on
  • PI 3 kinase depend signals

contraction

  • AMPK dependent signals (AMPK alpha, beta, gamma)
  • AMPK indepedent signals (Ca2+ activated)
35
Q

what is AMPK

  • how its activated
  • what does it do
A

AMP - activated protein kinase

  • responds to decrease energy status
  • less ATP, more ADP, AMP, P etc

stimulates atp-producing pathways, simutaneously inhibits ATP consuming pathways

36
Q

affect of exercise on glut4

A

rapid increase

  • 2fold glut4 mRNA
  • 50% protein in membrane
  • persists several hours

*why? glycogen replenish

37
Q

why would too high of skel. muscle glucose uptake be bad

A

rapid depletion of liver glycogen

  • hypoglycemia with continues exercise
  • “glycogen sparing”
38
Q

how to improve glycogen sparing

A

increase

  • mitochondria in muscle
  • fat oxidation enzymes

Nutr 4210 (16 decks)

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