Energy Metabolism in Muscle Flashcards Preview

MSS - MSK Exam 3 > Energy Metabolism in Muscle > Flashcards

Flashcards in Energy Metabolism in Muscle Deck (46):
1

main fuel in exercising muscles?

glycogen, glucose, free fatty acids

2

energy at rest?

predominantly fatty acids

3

high intensity isometric exercise energy?

anaerobic glycolysis and creatine kinase

4

submaximal exercise, low intensity?

blood glucose and free fatty acid

5

submaximal, high intensity?

more from glycogen and glucose
-glycogen main source

6

fatigue?

when glucose and glycogen stores are depleted

7

first hour of mild, low intensity?

glucose, glucagon and free fatty acids

8

one to four hours mild to moderate prolonged exercise?

free fatty acids increase substantially

**after four hours, free fatty acids main source

9

what maintains ATP levels?

glycogen and glucose metabolism
oxidative phosphorylation
creating kinase
purine nucleotide synthesis
lipid metabolism

10

anaerobic glycolysis

high intensity, isometric activity

results in fatigue - increasead lactate - acidification

11

aerobic glycolysis

dynamic isotonic exercise

pyruvate > acetyl CoA > TCA Cycle

12

rate limiting step in glycolysis?

fructose 6 P to fructose 1,6 BP
-enzyme: PFK

13

oxidative phosphorylation

18x more ATP than glycolysis alone

14

phosphocreatine pathway

enzyme: creatine kinase

phosphocreatine + ADP > ATP + creatine

duration of reaction is very small
-first 2-7 seconds

15

where is creatinephosphate synthesized?

liver and transported to muscle cells via bloodstream

16

location of creatine kinase?

skeletal muscle, heart, brain

17

CK 1

CK BB in brain, smooth muscles of lungs

18

CK 2

CK MB in heart

19

CK 3

CK MM in skeletal muscle

20

CK in blood tests?

elevation can indicate:
MI
rhabdomyolysis
muscular dystrophy
acute renal failure
drugs

21

purine nucleotide cycle

intensely exercising muscle can generate ATP over a short period using adenylate reaction

two ADP into ATP and AMP

22

fate of AMP

deaminated to IMP

enzyme: myoadenylate deaminase
-produced ammonia

higher in type 2 fast muscle fibers**

23

AMP deaminase?

AMP > IMP

releases ammonia

24

exercise induced myopathy and most common cause of metabolic myopathy?

deficiency in AMP deaminase

25

beta oxidation

of fatty acids

at rest - main energy substrate for muscles

26

what fatty acids can cross membrane?

less than 10 carbons
-can cross inner and outer mito membranes
-undergo beta oxidation

27

what happens with long chain fatty acids?

cannot cross mito membrane

activated by long chain acyl CoA synthetase
-to CoA thioester which crosses outer membrane

28

palmitoylcarnitine

transferred across inner mito membrane

-carnitine:acylcarnitine translocase

converted back to free acyl-CoA and carntine
-enzyme: CPT II

29

CPT I

combines acyl-CoA with carnitine

acylcarnitine can then be transferred across inner membrane

30

how does acylcarnitine get across inner membrane?

carnitine:acylcarnitine translocase

converted back to acyl-CoA (carnitine recycled outside)

acyl-CoA then is beta-oxidized

31

omega oxidation

of fatty acids

during prolonged fasting
-in liver peroxisome

forms DCAs which go through mitochondrial beta-oxidation

32

difference between beta ox and peroxisome ox

beta two separate enzymes
peroxisome ox one multifunction enzyme protein

33

zellweger syndrome

accumulation of long chain fatty acids
peroxisomal disorder

34

aderenoleukodystrophy

accumulation of long chain fatty acids
peroxisomal disorder

35

indicatin of omega ox?

DCAs in urine

36

inborn errors of fatty acid oxidation?

DCAs and acylglycine in urine
acylcarnitine derivatives in serum

37

cori cycle

recycles lactic acid

more efficient when muscle activity stops
oxygen debt can be made up

lactate > liver
-converted to pyruvate then to glucose (requires ATP)

38

what favors lactate production in skeletal muscle?

high NADH/NAD + ratio

intense exercise, increased lactate

drop in pH
-cramps

39

lactic acidosis sign of what?

MI
pulmonary embolism
uncontrolled embolism
uncontrolled hemorrhage

**any time we can't get blood to tissue

40

regeneration of NAD+

done by lactate formation (anaerobic glycolysis)

41

primary carnitine deficiency syndrome

lack of carnitine within cell (carnitine transporter mutation)
-lipid myopathy


fatty acid oxidation significantly reduced**

42

secondary carnitine deficiency syndrome

carnitine sequestered in form of acyl-carnitine
-carnitine cannot be removed from acyl group

defect in ACT II

elevated levels of acyl carnitine

fatty acid oxidation significantly reduced**

43

fatty acid transport defects

CPT I
CPT II
carnitine:acylcarnitine translocase

44

mitochondrial defects

defects of beta-oxidation enzymes

myopathic symptomes that are usually progressive

45

oxidative phosphorylation system

main source of energy in muscles and other cells

46

fasting?

omega oxidation (DCA production)