Scientists claim that the most complicated and mysterious thing in the universe is the Human Brain. Scientists know more about the stars that are exploding billions of light year away than they know about the human brain.
The brain is 75% water and has the consistency of tofu, custard, or gelatin. You could cut it with the knife. It weighs an average of three pounds, or 1.5 kg. and requires around 20% of the body's oxygen.
Every time you have a new thought, or recall a memory, a new brain connection is made between two or more brain cells.
Loss of oxygen for just 5 to 10 minutes can cause brain damage. The brain can stay alive for 4 to 6 minutes without oxygen, after that cells begin die.
Then there's gray and white matter. The gray matter (40%) is composed of neurons while the white matter (60%) consists of dendrites and axons.