Flashcards in 12/3 Muscle Metabolism Deck (31):
Illustrate an approximate time course of how exercising muscles regenerate ATP from the inital few seconds of exercise through one or more hours
Exercising muscle will initally use Adenaline Kinase and Creatine Kinase to generate ATP from stores of ADP and Creatine Phosphate respectively! Longer course: breakdown Glycogen to glucose for glycolysis (anarobic transitioning to arobic) Then long course use Fat oxydation to provide energy.
A reserve of High energy bonds in the muscles:
How does the muscle take advantage of creatine phosphate to maintain ATP levels in the muscle during the first few seconds of activity?
creatine phosphate plus ADP plus creatine kinase will give creatine and ATP!
How Could the muscle use ADP as a source of ATP during and initial burst of exercise?
it could use Adenaline kinase to convert two ADP to one ATP and one AMP!
What are the the two different types of muscle fibers?
Slow Twitch (Type I) and Fast Twitch (Type IIa, IIb)
Characterize Type I fibers
Type I: lots mitochondria/myoglobin; respiration/oxydative phosphorylation and resist fatigue, low glycogen content, develop force slowly but maintain longer than fast-twitch
Characterize Type IIa/IIb fibers
IIb(fast-glycolytic) -few mitochondria, low myoglobin, righ in glycogen and use glycogenolysis and glycolysis as primary energy source. Fatigue easily because lactic acid levels rise. Develop force greater and more quickly! (IIA are fast-oxidative glycolytic and are an inbetween)
What type of muscle fiber (IIa, IIb, I) would have more glycogen content
IIb! and IIa that is the fast glycolytic
what type of muscle fiber (I,IIa,IIb) would have higher myoglobin content
The type I because they are dowing more oxidation so more oxygen buffer provided by myoglobin content being high!
What type of muscle fiber (I,IIa,IIb) would have a highter lipoprtein lipase level?
Type I that is slow oxidative...using more fat oxydation for energy and therefore it would need to be trafficing more fat to themselves...(lipoprotein lipase is in the endothelial cells near them)
What type of muscle fiber (I,IIa,IIb) would have higher resisitance to fatigue?
The type I would be more resistant because they would need to act longer and they use fat stores for fuel.
what is the molecule that breaks and releases the fatty acids from fat stores in adipocytes?
hormone sensitive lipase is the most well known.
Case of very high creatine kinase, and dark urine with exercise and little food intake, trouble doing exercise for long periods...
This sounds like a type I muslce fiber problem in metabolizing fatty acids. Specifically it is a Carnitine palmitoyl transferase defect. (this gets the fatty acids into the mitochondria to metabolize them)
what type of muslces are type I?
they are the large, strong muscles that support stature and movement of limbs etc.
why would the urine be very dark when you have a break down of muscle cells?
they would release myoglobin into the blood and this would make the urine very dark!
what would indicate muscle damage in the blood and urine?
High Creatine kinase in the blood and high myogloblin in the urine.
When contrasting exercise at different VO2 max levels which level would be using more total calories?
when you are at higher VO2 max then you are using up more calories i.e. you are burning more caloreis and using more oxygen!
in a situation of burning more carbs or more fats when would the respiratory quotient be higher?
RQ = CO2 eliminated / O2 consumed So if the energy source is more reduced it will take more O2 to produce CO2 and the quotient would decrease (fats = 0.7; carbs = 1)
Why would AMP activate both glycogen phosphorylase and phosphofructokinase-1?
AMP is indicating that ATP is low therefore: glycogen phosphorylase activated to break off glucose from glycogen. Then phosphofructokinase commits us to glycolysis so now we have an energy source and a commited process.
High AMP would act to phosphorylate both acetyl CoA ccarboxylase and malonyl CoA decarboxylase how does the phosphorylation most likely affect the activity of these two enzymes
Acetyl CoA can be carboxylated to produce Malonyl CoA. Malonyl CoA inhibits the transfer of fatty acids into the mitochondria. if high AMP want low Malonyl CoA to up fatty acid metabolism in mitochondria. Therefore, deactivate the carboxylase and activate the decarboxylase.
what is phosphofructokinase 1?
Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP
what happens in the liver to PFK-1 when blood glucose is high?
it is phosphorilated and deactivated
what happens in muscle cells to PFK-1 when blood glucose is high
Skeletal: nothing; Cardiac: phosphorilated and upregulated (heart can do glycolysis when blood glucose is high).
How does the heart muscle get most energy?
aerobic metabolism, oxidizing fatty acids, glucose, and lactate, and they contain many mitochondria, with very little glycogen.
What chemical signal is sent out by the mitochondria to down regulate fatty acid import by up reg. the produciton of malonylCoA?
What do muslces use as fuel at rest?
what is available in the blood (glucose, amino acids, fatty acids)
What do muscles use as fuel during starvation?
fatty acids are the preferred energy source (even over ketone bodies)
What do muscles use as fuel during exercise
stored glycogen, blood glucose, and blood fatty acids
what would stimulate muscle building?
Exercise; Insulin; Testosterone (steroid horomone).
what would inhibit muscle synthesis and cause breakdown
fasting: insulin low and cortisol high (stressed too)