Question

What is the process involved in the mechanism of muscle contraction?

Answer 1

To explain this process there is a theory "SLIDING FILAMENT THEORY" :-

In summary the sliding filament theory of muscle contraction can be broken down into four distinct stages, these are;

1. Muscle activation:  The motor nerve stimulates an action potential (impulse) to pass down a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to release calcium into the muscle cell.
 
2. Muscle contraction:  Calcium floods into the muscle cell binding with troponin allowing actin and myosin to bind.  The actin and myosin cross bridges bind and contract using ATP as energy (ATP is an energy compound that all cells use to fuel their activity – this is discussed in greater detail in the energy system folder here at ptdirect).
 
3. Recharging:  ATP is re-synthesised (re-manufactured) allowing actin and myosin to maintain their strong binding state
 
4. Relaxation:  Relaxation occurs when stimulation of the nerve stops.  Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.  Alternatively relaxation (failure) will also occur when ATP is no longer available.
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Hope it helped

Answer 2

Pura padhna...

vrna isme tera ghata mera kuch nhi jaata..

:)

Calcium is released from the sarcoplasmic reticulum at the time of muscle contraction ....

This calcium binds with Stark troponin I tropomyosin Complex on the actin filament molecules

the complex shifts and the myosin binding sites on actin filaments are exposed ...

Myosin head have actin binding sites as well as ATP sites..

Myosin head binds with the actin filaments and hydrolysis of ATP takes place that pushes the thin actin over the thick myosin filament ...

The thin filaments slide over the thick filament according to sliding filament theory...

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