Still it is not that subtle.
It is this heart which somehow controls in an integrated manner, by its life-feed, the blood circulation done by the physical heart, the passage of breath conducted by the physical lungs, the functions of the nerves prompted by the physical brain and the functions that take place in the digestive organs and the associated passages.
It does this control through the nADis that start from it.
Without the feeling of ‘I’ in the JIva, what can happen in a body?
That is why this ‘power’ has been given to the heart which is the locale for the ego.