If one thinks about it ATP is really supplying energy for th

If one thinks about it, ATP is really supplying energy for the relaxation to happen since most of it is used in pumping calcium ions. Why is that important?

Solution

The excitation, contraction and relaxation processes require ATP. These processes are accomplished in 4 steps and they are as follows:

ATP is split by myosin ATPase and provides energy for the power stroke to occur in the cross bridge.

Binding of a fresh molecule of ATP to myosin detaches the cross bridge from actin filament at the end of the power stroke cycle. But the cycle is repeated by splitting of ATP later to provide energy for the next power stroke.

The Ca²⁺ ions are actively transported back into lateral sacs of sarcoplasmic reticulum during the relaxation and require energy provided by split of ATP.

The ATP dependent Na⁺ - K⁺ ion pump actively sent back the ions (Na⁺ out of the cell and K⁺ into the cell) that are generated during contraction inducing action potential in the muscle cell.

Since, muscle contraction and relaxation are cyclic processes, the energy supplied by ATP is very i mportant to perform the contiuos cyclic actions.