PHYSIOLOGY
MUSCLE CONTRACTION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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actin
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myosin
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calcium
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ATP
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Detailed explanation-1: -Thick filaments are formed by the association of several hundred myosin II molecules in a staggered array. The globular heads of myosin bind actin, forming cross-bridges between the myosin and actin filaments .
Detailed explanation-2: -Once the myosin forms a cross-bridge with actin, the Pi disassociates and the myosin undergoes the power stroke, reaching a lower energy state when the sarcomere shortens. ATP must bind to myosin to break the cross-bridge and enable the myosin to rebind to actin at the next muscle contraction.
Detailed explanation-3: -The increase of calcium concentration within the microfibules is what allows the cross bridge cycle to take place. The cross bridges cannot form without calcium because calcium is what allows the active sites to become exposed and without exposed acctive sites, the bridges cannot form.