Flashcards in Energy Metabolism in Muscle Deck (46)
main fuel in exercising muscles?
glycogen, glucose, free fatty acids
energy at rest?
predominantly fatty acids
high intensity isometric exercise energy?
anaerobic glycolysis and creatine kinase
submaximal exercise, low intensity?
blood glucose and free fatty acid
submaximal, high intensity?
more from glycogen and glucose
-glycogen main source
when glucose and glycogen stores are depleted
first hour of mild, low intensity?
glucose, glucagon and free fatty acids
one to four hours mild to moderate prolonged exercise?
free fatty acids increase substantially
**after four hours, free fatty acids main source
what maintains ATP levels?
glycogen and glucose metabolism
purine nucleotide synthesis
high intensity, isometric activity
results in fatigue - increasead lactate - acidification
dynamic isotonic exercise
pyruvate > acetyl CoA > TCA Cycle
rate limiting step in glycolysis?
fructose 6 P to fructose 1,6 BP
18x more ATP than glycolysis alone
enzyme: creatine kinase
phosphocreatine + ADP > ATP + creatine
duration of reaction is very small
-first 2-7 seconds
where is creatinephosphate synthesized?
liver and transported to muscle cells via bloodstream
location of creatine kinase?
skeletal muscle, heart, brain
CK BB in brain, smooth muscles of lungs
CK MB in heart
CK MM in skeletal muscle
CK in blood tests?
elevation can indicate:
acute renal failure
purine nucleotide cycle
intensely exercising muscle can generate ATP over a short period using adenylate reaction
two ADP into ATP and AMP
fate of AMP
deaminated to IMP
enzyme: myoadenylate deaminase
higher in type 2 fast muscle fibers**
AMP > IMP
exercise induced myopathy and most common cause of metabolic myopathy?
deficiency in AMP deaminase
of fatty acids
at rest - main energy substrate for muscles
what fatty acids can cross membrane?
less than 10 carbons
-can cross inner and outer mito membranes
-undergo beta oxidation
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
transferred across inner mito membrane
converted back to free acyl-CoA and carntine
-enzyme: CPT II
combines acyl-CoA with carnitine
acylcarnitine can then be transferred across inner membrane