Question

The sliding filament hypothesis explains the contraction of muscle myofilaments. Outline, illustrate or describe this process below, including the initiating occurrence(s) at the nerve. Relate these occurrences to the stages of the muscle action potential

Answer 1

Sliding filament theory explains how myosin filament attaches itself to the actin filament. It tells how actin filament slides over myosin filament.

Stages of muscle contraction are-

1. A nerve impulse travels to the neuromuscular junction. It is a junction between a neuron and a muscle.

2. Acetylcholine is released from the axon to receptors located on the sarcolemma.

. Binding of acetylcholine causes depolarization of the sarcolemma membrane which opens sodium channels and allows sodium ions to enter inside the cell.

4. This depolarizes the entire membrane of the sarcolemma. This creates a wave of an action potential.

5. The action potential travels across the sarcolemma down the T tubules which triggers sarcoplasmic reticulum to release calcium ions.

6. This calcium then binds to troponin and removes tropomyosin from the sites where myosin head will bind.

7. Now myosin head attaches itself to the sites.

8. For initiating a power stroke a molecule of ATP is required.

9. Now myosin head is cocked and initiates a power stroke. In a power stroke it pulls actin filaments and a molecule of ATP is hydrolyzed.

10. Now one more molecule of ATP will bind to the myosin head and it will be hydrolyzed which will help myosin filament to detach from actin.