The Human brain is made up of 76% water consists of 40% grey mater which is made up of neurons and dendrites and 60% white matter which is made up of Axons that send signals through each other.
Communication happens through these neurons that send signals through the dendrites to the axons. There are over one billion neurons in the human brain which is actually more than the stars in our galaxy.
This sounds quite disquieting but it has been found that every minute, approximately 750 ml to 1000 ml of blood flows through our brains which if you measure in terms of soda cans is like three cans full of blood. Weird, right?
And another fascinating thing about it is that 3/4th of the human brain actually develops outside the womb.