Medshotsover 8 years ago

Human brain

• The human brain is the largest brain of all vertebrates relative to body size.• It weighs about 3.3 lbs. (1.5 kilograms).• The brain makes up about 2 percent of a human's body weight.• The cerebrum makes up 85 percent of the brain's weight.• It contains about 86 billion nerve cells (neurons) — the "gray matter". It also contains billions of nerve fibers (axons and dendrites) — the "white matter", These neurons are connected by trillions of connections, or synapses.