PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Lack of effort
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Myosin-Heads fail to attach
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Calcium Ions are pumped away
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Muscle fibre tears
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Detailed explanation-1: -A muscle also can stop contracting when it runs out of ATP and becomes fatigued ([link]). Ca++ ions are pumped back into the SR, which causes the tropomyosin to reshield the binding sites on the actin strands. A muscle may also stop contracting when it runs out of ATP and becomes fatigued.
Detailed explanation-2: -Abstract. Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin. Two different regulatory systems are found in different muscles.
Detailed explanation-3: -Relaxation: Relaxation occurs when stimulation of the nerve stops. Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.
Detailed explanation-4: -As the action potential decays, the calcium ions are actively pumped back into the sarcoplasmic reticulum with the SERCAs pump (Sarcoplasmic/endoplasmic reticulum calcium ATPase).
Detailed explanation-5: -Inside the muscle fibre, the T-tubules lie next to the terminal cisternae of an internal membrane system derived from the endoplasmic reticulum, called the sarcoplasmic reticulum (SR), which is a store of calcium ions.