Question

Select the correct option:
i) Muscle contraction takes place by sliding of thick filaments over thin filaments.
ii) When the neural signal reaches the neuromuscular junction, it releases acetylcholine, which helps generate an action potential in the muscle fibre.
iii) Muscle contraction begins by a signal sent by the peripheral nervous system by a motor neuron.

• A. Only i is correct
• B. Only ii and iii are correct
• C. Only ii is correct
• D. All are correct

Answer 1

The correct option is C Only ii is correct

Muscle contraction is best explained by the sliding filament theory. According to this theory, muscle contraction takes place by sliding of thin filaments over thick filaments. The signal that initiates the muscle contraction is sent by the central nervous system with the help of a motor neuron (nerve cell that passes from the central nervous system to the muscle). This neural signal reaches the neuromuscular junction (junction between motor neuron and sarcolemma). It helps release a neurotransmitter called acetylcholine which generates an action potential (membrane potential of the muscle fibre rapidly rises and falls).