Energy Metabolism in Muscle

Question 1

main fuel in exercising muscles?

Answer 1

glycogen, glucose, free fatty acids

Question 2

energy at rest?

Answer 2

predominantly fatty acids

Question 3

high intensity isometric exercise energy?

Answer 3

anaerobic glycolysis and creatine kinase

Question 4

submaximal exercise, low intensity?

Answer 4

blood glucose and free fatty acid

Question 5

submaximal, high intensity?

Answer 5

more from glycogen and glucose

-glycogen main source

Question 6

fatigue?

Answer 6

when glucose and glycogen stores are depleted

Question 7

first hour of mild, low intensity?

Answer 7

glucose, glucagon and free fatty acids

Question 8

one to four hours mild to moderate prolonged exercise?

Answer 8

free fatty acids increase substantially

**after four hours, free fatty acids main source

Question 9

what maintains ATP levels?

Answer 9

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

Question 10

anaerobic glycolysis

Answer 10

high intensity, isometric activity

results in fatigue - increasead lactate - acidification

Question 11

aerobic glycolysis

Answer 11

dynamic isotonic exercise

pyruvate > acetyl CoA > TCA Cycle

Question 12

rate limiting step in glycolysis?

Answer 12

fructose 6 P to fructose 1,6 BP

-enzyme: PFK

Question 13

oxidative phosphorylation

Answer 13

18x more ATP than glycolysis alone

Question 14

phosphocreatine pathway

Answer 14

enzyme: creatine kinase

phosphocreatine + ADP > ATP + creatine

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

Question 15

where is creatinephosphate synthesized?

Answer 15

liver and transported to muscle cells via bloodstream

Question 16

location of creatine kinase?

Answer 16

skeletal muscle, heart, brain

Question 17

CK 1

Answer 17

CK BB in brain, smooth muscles of lungs

Question 18

CK 2

Answer 18

CK MB in heart

Question 19

CK 3

Answer 19

CK MM in skeletal muscle

Question 20

CK in blood tests?

Answer 20

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

Question 21

purine nucleotide cycle

Answer 21

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

two ADP into ATP and AMP

Question 22

fate of AMP

Answer 22

deaminated to IMP

enzyme: myoadenylate deaminase
- produced ammonia

higher in type 2 fast muscle fibers**

Question 23

AMP deaminase?

Answer 23

AMP > IMP

releases ammonia

Question 24

exercise induced myopathy and most common cause of metabolic myopathy?

Answer 24

deficiency in AMP deaminase

Question 25

beta oxidation

Answer 25

of fatty acids at rest - main energy substrate for muscles

Question 26

what fatty acids can cross membrane?

Answer 26

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

Question 27

what happens with long chain fatty acids?

Answer 27

cannot cross mito membrane activated by long chain acyl CoA synthetase -to CoA thioester which crosses outer membrane

Question 28

palmitoylcarnitine

Answer 28

transferred across inner mito membrane -carnitine:acylcarnitine translocase converted back to free acyl-CoA and carntine -enzyme: CPT II

Question 29

CPT I

Answer 29

combines acyl-CoA with carnitine acylcarnitine can then be transferred across inner membrane

Question 30

how does acylcarnitine get across inner membrane?

Answer 30

carnitine:acylcarnitine translocase converted back to acyl-CoA (carnitine recycled outside) acyl-CoA then is beta-oxidized

Question 31

omega oxidation

Answer 31

of fatty acids during prolonged fasting -in liver peroxisome forms DCAs which go through mitochondrial beta-oxidation

Question 32

difference between beta ox and peroxisome ox

Answer 32

beta two separate enzymes | peroxisome ox one multifunction enzyme protein

Question 33

zellweger syndrome

Answer 33

accumulation of long chain fatty acids | peroxisomal disorder

Question 34

aderenoleukodystrophy

Answer 34

accumulation of long chain fatty acids | peroxisomal disorder

Question 35

indicatin of omega ox?

Answer 35

DCAs in urine

Question 36

inborn errors of fatty acid oxidation?

Answer 36

DCAs and acylglycine in urine | acylcarnitine derivatives in serum

Question 37

cori cycle

Answer 37

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)

Question 38

what favors lactate production in skeletal muscle?

Answer 38

high NADH/NAD + ratio intense exercise, increased lactate drop in pH -cramps

Question 39

lactic acidosis sign of what?

Answer 39

MI pulmonary embolism uncontrolled embolism uncontrolled hemorrhage **any time we can't get blood to tissue

Question 40

regeneration of NAD+

Answer 40

done by lactate formation (anaerobic glycolysis)

Question 41

primary carnitine deficiency syndrome

Answer 41

lack of carnitine within cell (carnitine transporter mutation) -lipid myopathy fatty acid oxidation significantly reduced**

Question 42

secondary carnitine deficiency syndrome

Answer 42

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**

Question 43

fatty acid transport defects

Answer 43

CPT I CPT II carnitine:acylcarnitine translocase

Question 44

mitochondrial defects

Answer 44

defects of beta-oxidation enzymes myopathic symptomes that are usually progressive

Question 45

oxidative phosphorylation system

Answer 45

main source of energy in muscles and other cells

Question 46

fasting?

Answer 46

omega oxidation (DCA production)