Skeletal muscle Flashcards
what are the three main types of muscle
skeletal, cardiac and smooth
what does skeletal muscle do
used to move limbs
what does smooth muscle do
used to move substances through organs
what does cardiac muscle do
used to pump blood
what is the name for the type of pairs that skeletal muscle comes in and what does it mean
antagonistic pairs, as one contracts the other relaxes
which types of muscles are striated
cardiac and skeletal
which type of muscle is branched
cardiac
which type of muscle is multinucleated
skeletal
what is a muscle fibre
a muscle cell
what are myofibrils
the tube like structures that are inside the muscle fibres
what are the two types of protein filaments within the myofibrils
actin and myosin
what are actin filaments made of
two actin filaments wrapped around each other and tropomyosin
what are myosin filaments made up of
two myosin filaments wrapped around each other with a head and a tail
what is a sarcomere
a section inside a myofibril that is made up of a vertical stack of at least 4 thin filaments and one thick filament, repeats
what is the middle of a sarcomere in the thick filaments called
the M line
what is the line at the midpoint of two M lines called
the Z line
how many Z lines and M lines are there in one sarcomere
1 M line and 2 Z lines
which areas of a sarcomere are light and dark
the thin filaments appear as light and the thick filaments appear as dark
what are I bands
the areas of a sarcomere that appear lighter
what are the A bands
the areas of a sarcomere that appear darker
what is the H zone in a sarcomere
the lighter bit in the dark bit (a band ), appears lighter because its made of only thick filaments
what triggers the actin and myosin to move
an action potential in the muscle fibre, calcium ions
what does calcium trigger within a myofibril
triggers tropomyosin to change shape and move away from the binding sites
within the muscle fibre where are calcium ions released from
the sarcoplasmic reticulum
when the myosin head attaches to the binding site on the actin what does it form
actinomyosin bridge
what reaction myosin heads catalyse
the conversion of ATP into ADP and a phosphate ion
what does the energy from the hydrolysis of ATP allow the myosin head to do
take its starting position
what happens when the myosin attaches to the actin binding site
ADP and the phosphate ion are released from the myosin head active site which allows the myosin head to change its angle and move the actin (the power stroke)
what happens after the myosin head has completed the power stroke
another molecule of ATP comes along and binds to the myosin head causing it to detach from the actin, myosin head hydrolyses ATP which releases energy and allows it to go back to its starting position
what is the name of the mechanism for which muscles contract
the sliding filament mechanism
