Select the correct statements regarding mechanism of muscle contraction. A. It is initiated by a signal sent by CNS via sensory neuron. B. Neurotransmitter generates action potential in the sarcolemma. C. Increased Ca ^ ++ level leads to the binding of calcium with troponin on action filaments. D. Masking of active site for actin is activated. E. Utilising the energy from ATP hydrolysis to form cross bridge. Choose the most appropriate answer from the options given below:
A. B, C and E only
The correct answer is option (1) as muscle contraction is initiated by a signal sent by the CNS via a motor neuron. A neural signal reaching the neuromuscular junction releases a neurotransmitter (acetylcholine) which generates an action potential in the sarcolemma. This spreads through the muscle fibre and causes the release of Ca ^ 2 * into the sarcoplasm. Increase in Ca ^ 2+ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin. Utilising the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.
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