PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Action potential generated is propagated along the sacrolemma and down the T tubules.
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Action potential triggers calcium release from terminal cisternae of SR.
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Removal of calcium by active transport into the SR after the action potential ends.
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None of the above
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Detailed explanation-1: -Skeletal muscle contraction begins first at the neuromuscular junction, which is the synapse between a motoneuron and a muscle fiber. Propagation of action potentials to the motoneuron and subsequent depolarization results in the opening of voltage-gated calcium (Ca2+) channels of the presynaptic membrane.
Detailed explanation-2: -Excitation-contraction coupling begins with depolarization and spread of an AP along the sarcolemma (point 2 in Figure 2-10) and continues with the propagation of the AP into the T tubules (point 2 in Figure 2-10).
Detailed explanation-3: -Depolarisation and calcium ion release. Actin and myosin cross-bridge formation. Sliding mechanism of actin and myosin filaments. Sarcomere shortening (muscle contraction)