GENERAL HISTOLOGY

MUSCLE

SKELETAL MUSCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What causes the force of the contraction?
A
acetylcholine
B
myosin moving
C
Calcium
D
actin moving
Explanation: 

Detailed explanation-1: -Myosin bound by ADP and inorganic phosphate (Pi) can then form cross-bridges with actin, and the release of ADP and Pi produces the power stroke that drives contraction. This force causes the thin actin filament to slide past the thick myosin filament and shortens the muscle.

Detailed explanation-2: -As discussed later, the motor activity of myosin moves its head groups along the actin filament in the direction of the plus end. This movement slides the actin filaments from both sides of the sarcomere toward the M line, shortening the sarcomere and resulting in muscle contraction.

Detailed explanation-3: -Abstract. Muscle force is generated by myosin crossbridges interacting with actin. As estimated from stiffness and equatorial X-ray diffraction of muscle and muscle fibres, most myosin crossbridges are attached to actin during isometric contraction, but a much smaller fraction is bound stereospecifically.

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