contraction of skeletal muscle Flashcards
what does the sarcoplasm have a lot of
mitochondria
where are the myofibrils found
sarcomere
what are the two components of myosin
fibrous filament
globular
what is actin made of
globular proteins
tropomyosin
what is tropomyosin
long chains around actin
what is the first step of muscle contraction
calcium ions enter the sarcoplasmic reticulum
how do calcium ions enter
through active transport
how does calcium ions enter and where does it go from
active transport from the sarcoplasm to the sarcoplamic reticulum
what does the presence of calcium ions cause
tropomyosin to move off the actin exposing actin binding sites
what does the exposing of actin binding sites mean
myosin head binds to actin binding site
what also binds to the actin-binding site
adp
what is created when the myosin head binds to actin binding site
crossbridge
how does this then cuase muscle contraction
myosin head then becomes cocked and pulls the actin over the myosin
what does the pulling of the actin over the myosin cause
causes ADP to be released
after ADP is released what happens to the myosin head
an ATP molecule binds to myosin head
what does the binding of ATP onto myosin cuase
causes the myosin head to dettach from the actin
once dettached then what happens
ATP is hydrolised
what is Atp hydrolised by
ATPase
what does the hydrolisis of atp cause
causes the ADP to dettach from myosin head
what does dettachment of ATP mean for myosin
myosisn head returns to normal
now the myosin head has returned to normal what can happen
ADP and Pi can attach to myosin head
what does this mean this process is
cyclical
what can help increase speed of muscle contraction
phosphocreatine
what does phosphocreatine do
readily supplies phosphate meaning that the conversion / phosphorylation of ADP to ATP can happen more readily
