4+5. integrative metabolism carbohydrates Flashcards Preview

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Flashcards in 4+5. integrative metabolism carbohydrates Deck (38):
1

plasma-derived substrates

glucose and fatty acids
- supply most energy at low intensities

2

endogenous substrates

glycogen and triglycerides
- more important at higher intensities
- 65% vo2 max

3

later stages of exercise
- source of energy

plasma source of substrate more important
- endogenous sources decline

4

higher intensities of exercise

endogenous more important
- CHO

5

longer duration of exercise

plasma-derived substrates more important
- FFAs

6

blood glucose concentration regulation
- maintenence value

hepatic glucose production (HGP)
- approx 4-5mM
- tighter compared to FFA (0.2-2mM)

7

tissues that depend on glucose

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

8

maximum leg glucose uptake
- problem (total blood glucose content)

~ 2 mM/min
- total blood gluc content only 20mM
- theoretically depleted in 10min
- liver compensates

9

glycogen bonds

straight
- alpha 1,4 bonds

branching
- alpha 1,6 bonds

10

enzymes that breakdown glycogen
- pathway and substrate produced

glycogen phosphorylase
- alpha 1,4 bonds

debranching enzyme
- alpha 1,6 bonds

*glycogenolysis produces G6P (glucose-6-phosphate)

11

G6P in "liver" during exercise

converted to glucose
- exported to systemic circulation

12

G6P in "muscle" during exercise

used for anaerobic and aerobic metabolism for the muscle
- glycolysis
- converted to pyruvate

*can NOT be converted to glucose

13

glycogen utilization
- rate of depletion fasting during

onset of exercise

14

glycogen utilization curve
- duration
- intensity

exponential curves
- decline with time
- incline with intensity

15

liver glycogen utilization
- how quickly can it be used in 1hr

can utilize 50% in 1hr

16

glycogen sparing definition
- what improves it

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

17

liver gluconeogenesis with exercise
- increasing intensity
- recovery**

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

liver glycogenolysis and gluconeogenesis with increasing intensities

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

gluconeogenesis (GNG) defn
- substrates

glucose synthesis from non-carbohydrate sources
- pyruvate
- lactate
- glycerol
- some AAs

*muscle does NOT have enzymes for GNG

20

gluconeogenesis pathway
- starting substrates
- intermediates

start
- pyruvate (cytosol)
- lactate
- aminos
intermediates
- glycerol
- oxaloacetate (mitochondria)

21

regulation of gluconeogenesis by cAMP

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

glycolysis produced

pyruvate

23

anaerobic pathway of pyruvate

anaerrobic "reduction"
- lactate dehydrogenase (LDH)
- lactic acid
- lactate + H ion

24

aerobic pathway of pyruvate

aerboic "oxidation"
- pyruvate dehydrogenase (PDH)
- acetyl coA (mitochondria)
- citric acid cycle

25

formation of ATP from pyruvate

substrate level phosphorylation

26

lactic acid when at pH of 7

in lactate form

27

importance of lactate production

produces NAD+ when oxygen in short supply
- allows glycolysis to continue

28

fate of lactate

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

cori cycle

liver GNG
- 2 lactate --> 2 pyruvate --> glucose
- costs 6 atp

30

what is the cause of muscle soreness

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

*not lactic acid buildup

31

lactate threshold (LT)

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

training accelerates lactate clearance

32

effect of glucose transport with exercise

rapid increase
- persists several hours after post exercise

33

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

activated by
1. insulin
2. contractile activity

***additive affect***

34

how insulin and contractile activity effect glucose transport

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

what is AMPK
- how its activated
- what does it do

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

affect of exercise on glut4

rapid increase
- 2fold glut4 mRNA
- 50% protein in membrane
- persists several hours

*why? glycogen replenish

37

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

rapid depletion of liver glycogen
- hypoglycemia with continues exercise
- "glycogen sparing"

38

how to improve glycogen sparing

increase
- mitochondria in muscle
- fat oxidation enzymes