how an elictric current damage human body?

Electric current can block the normal functions of nerve cells, which can cause anything from a mildtingle to a major heart attack. And Electrical burns can be caused when electricity arcs. They are essentially treated like any otherburn.

Electric current affects the body by causing burns due to the heat generated due to resistance of human body.

But current has a more severe affect on our heart as current can lead to defribillation i.e. stopping of heart.

A curren of as low as 30-40 mA can kill a human.