Biocehemistry- Muscle Metabolism Flashcards
give 5 qualities of type I fibers
fatigue resistant, high myoglobin, high oxidative capacity, low glycogen content and glycolytic capacity
where does most of cardiac ME come from
fatty acids
how come ATP levels do not fall when muscle is elctronically twitched
because of the replishment of ATP via CK
what muscle enzyme operates to maintain ATP levels and prevent the accumulation of ADP.
Adenylate cyclase
ATP levels fall very little until ____
fatigue is approached
In fast twitch muscle fibers ATP and phosphocreatine stores only sustain vigourous cotnraction for ____ and then _____ must be utilized to replenish ATP
a few seconds, metabolism
Initial ATP production is achieved by switching on
glycolysis
In type IIA and IIB fibers, the glucose substrate for glycolysis may come from _____ ______, especially in vigorous contraction.
muscle glycogen
In times of stress, ________ will activate glycogen breakdown even more potently.
epinephrine
______, ______, and ________ all activate phosphofructokinase 1 (PFK 1), the controlling enzyme of glycolysis.
AMP, Pi and NH3
____level is probably primarily responsible for activation of PFK-1 (and consequently glycolysis) on the initial contraction of muscle. Also activates glycogen phosphorylase b
AMP
is a glycogen storage disease (Type V) resulting from a genetic deficiency of muscle glycogen phosphorylase. It results in unusual fatigue and painful muscle cramps on exercise.
McArdle’s Disease
___ activates isocitrate dehydrogenase
ADP
Overall in muscle, at rest,______is the major source of ATP except after a high carbohydrate meal.
lipid
During intense exercise, ______ is the major source (over short periods, glycogen in fiber types IIa and IIb).
carbohydrate
one major disadvantage of carbohydrate usage is that it
produces about 7 times less energy per gram
how do we overcome the carbohydrate problem
having small stores of glycogen for use in extreme conditions requiring high power output.
continued heavy breathing after cessation of vigorous exercise in order to convert lactate back to pyruvate and NADH re-oxidized
Oxygen Debt
Lactate can diffuse out of muscle and be transported to the liver, where it can be converted to glucose by gluconeogenesis. Known as _____ ____
Cori Cycle
Is muscle fatigue directly due to the accumulation of lactate ( what is the most significant contributor)
NO……fuck NO (Phosphate, decreased pH)
what is a mjaor controlling enzyme in glycolosysi
PFK1
Increased _______levels in the brain could lead to increased levels of serotonin, which promotes relaxation and sleep
tryptophan
The controlling enzyme of glycogen synthesis is ____________ (glucosyl transferase) Insulin, released in response to intake of glucose, activates this enzyme.
(G-6-P also stimulates its non-active form).
glycogen synthetase
At rest, types I and IIA fibers produce their ATP from ____and _____, mostly _____ except after a high carbohydrate meal.
lipid, glucose, lipid
Muscles containing a higher proportion of red fibers have higher____ activity.
LPL
lipolysis is switched on by _____ and ______
epinephrine and glucagon
FABP is present in cells with a greater ____ capacity, such as ______
oxidative, cardiac cells
endurance training enhances the ability of type __ and ___ fibers to oxidize fatty acids
I, IIA
At rest, types I and IIA muscle fibers preferentially use _________ as fuel.
fatty acids
fatty acids are metabolized to _____ which inhibits pyruvate dehydrogenase
acetyl coa
acetyl coa is then coverted to ___ which inhibits PFK
citrate
how does glucose take over as the source of energy after a high carbohydrate meal
secretes insulin which inhibits lipolysis,
early stages of fasting the major source of energy is_____ _____.
This reserves all available glucose for the brain
fatty acids
In starvation, the degradation of muscle proteins provides the carbon skeletons of amino acids for gluconeogenesis by the liver
yea, they do
Quantitatively muscle releases far more alanine and glutamine
yep
