lecture 9.5 main points Flashcards
when is skeletal muscle at low activity? describe ATP use
when relaxed, only using a moderate amount of ATP
when is skeletal muscle at high activity? describe ATP use
when contracting, using ATP at a rapid pace
why is ATP important for skeletal muscle cells
ATP is the only source used directly for contractile activities
move and detach cross bridges, power calcium pumps in SR and sarcolemma , power return of Na and K to normal levels after excitation
how long does accumulated ATP power the muscle contraction at its onset? what must occur if the muscle is to continue contraction?
3-6 seconds, in order to continue contraction muscle must make more ATP
regeneration of ATP- direct phosphorylation
direct phosphorylation of ADP using creatine phosphate
(adding a phosphate)
especially important in muscle fibers
where is most creatine found in the body
in skeletal muscle
regeneration of ATP - anaerobic pathway
glycolysis to make lactic acid, no oxygen required
glycolysis followed by fermentation
regeneration of ATP - aerobic pathway
glycolysis makes oxygen and modified glycolysis products into mitochondria
what is creatine and where is it made in the body
creatine is a small amino acid derived molecule that is made in the liver, kidneys, and pancreas
what are some dietary sources of creatine
milk, red meat, some fish
describe ATP production and ATP use by the muscle cell at rest
when relaxed, muscle fibers produce more ATP than is needed for resting metabolism (use is low)
at rest, what is the excess ATP used to make
creating phosphate
what transfers a phosphate from ATP to creatine creating creatine phosphate
creatine kinase (an enzyme)
this forms CP and ADP
what chemical environment is necessary for the formation of creating phosphate - an abundance or declining amount of ATP
abundance
at rest, contrast ATP amounts vs CP
CP is 3-6 more plentiful than ATP when a muscle is relaxed
what happens to ATP levels when muscle contracts and uses more ATP than it is making
during contraction, ATP levels decline
during contraction what happens to ADP levels vs ATP levels
ADP levels increase in sarcoplasm
how does creatine kinase respond to the decrease in ATP and rise in ADP with respect to creatine phosphate? how much additional contraction time does this allow for ?
CK takes phosphate back from CP and adds its to ADP creating ATP.
allows for roughly 15 seconds of contraction time
at rest, when a phosphate it taken from ATP what is left over?
ADP and creatine phosphate
when phosphate is added to creatine, what does creatine become
creatine phsophate
during contraction, when is phosphate is taken from creatine phosphate, what is left
creatine
during contraction, when a phosphate is added to ADP what is formed?
ATP
what is the metabolite (breakdown product) of creatine called
creatinine
how is creatinine gotten rid of by the body
filtered by the kidneys into the urine