1
Question
Choose the correct sequence of events for the mechanism of muscle contraction:
I. Increase in Ca2+ level leads to the binding of calcium with a subunit of troponin on actin filaments which results in the removal of masking of active sites for myosin.
II. The 'Z' line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere. i.e., contraction.
III. Neural signal reaching the motor end-plate releases acetylcholine resulting in generation of action potential in sarcolemma.
IV. The attached actin filaments are pulled towards the centre of 'A' band
Choose the correct sequence of events for the mechanism of muscle contraction:
I. Increase in Ca2+ level leads to the binding of calcium with a subunit of troponin on actin filaments which results in the removal of masking of active sites for myosin.
II. The 'Z' line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere. i.e., contraction.
III. Neural signal reaching the motor end-plate releases acetylcholine resulting in generation of action potential in sarcolemma.
IV. The attached actin filaments are pulled towards the centre of 'A' band
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Solution
The correct option is C III, I, IV, II
Neural signal reaching the motor end plate releases neurotransmitters (acetylcholine) resulting in generation of action potential in sarcolemma. Action potential spreads through the muscle fibre and results in the release of calcium ions into the sarcoplasm. Increase in Ca2+ level leads to the binding of calcium with a subunit of troponin on actin filament. It results in the removal of masking of active sites for myosin. Myosin head utilises the energy from ATP hydrolysis and binds to the exposed active sites on actin to form a cross bridge. The attached actin filaments are pulled towards the centre of 'A' band. The 'Z' line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere i.e., contraction.
Neural signal reaching the motor end plate releases neurotransmitters (acetylcholine) resulting in generation of action potential in sarcolemma. Action potential spreads through the muscle fibre and results in the release of calcium ions into the sarcoplasm. Increase in Ca2+ level leads to the binding of calcium with a subunit of troponin on actin filament. It results in the removal of masking of active sites for myosin. Myosin head utilises the energy from ATP hydrolysis and binds to the exposed active sites on actin to form a cross bridge. The attached actin filaments are pulled towards the centre of 'A' band. The 'Z' line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere i.e., contraction.