What is a shakra?
I think you mean Chakra. A Chakra is like a artery for the "spirit". Chakras help to maintain a continueous flow of "energy" through the non-physical body. They can also adversly effect the physical body, ie. if your chakras are unbalanced, you feel poorly or even ill. Look up TREE OF LIFE or KABALA. These are where the idea of Chakras originates. The body has 6 to 7 major chakras. There are minor chakras all over the body. The Chinese call it the Meridian System. ==new answer== The function of a chakra is to return used energy back to mind. Each major chakra corresponds with a level of mind of which there are seven. There is much detail about this in the interpretation of revelation of the bible in the universal language of mind.
As we control the productive use of energy, we have more.