Question

Choose the correct sequence of events in case of sliding filament theory:
I. Acetylcholine generates an action potential in the sarcolemma
II. F-actin binds myosin head
III. Inflow of Na+ ions
IV. CNS sends the command via motor neuron and the signal reaches the
neuromuscular junction
V. Thin filament moves inwards and reduces the length of I band
VI. Calcium ions release into the sarcoplasm
VII. Conformational changes in the troponin

• A. I → II → III → IV → V → VI → VII
• B. IV → I → III → VI → VII → II → V
• C. IV → I → VI → III → V → VII → II
• D. IV → I → VI → III → VII → II → V

Answer 1

The correct option is B IV → I → III → VI → VII → II → V

The sliding filament theory explains the mechanism of muscle contraction. Correct order of the steps involved in the process of muscle contraction are:
1. CNS sends the command via motor neuron and the signal reaches the neuromuscular junction
2. Acetylcholine generates an action potential in the sarcolemma
3. Inflow of Na+ ions
4. Calcium ions release into the sarcoplasm
5. Conformational changes in the troponin
6. F-actin binds myosin head
7. Thin filament moves inwards and reduces the length of I band