•The human brain is the largest brain of all vertebrates relative to body size. •It weighs about 3.3 lbs (1.4 Kg). • The brain makes up about 2% of the human's body weight. • The cerebrum is the largest part of the brain and makes up about 85% of the brain weight. •Brain contain over 86 billion nerve cells (neurons), comprising the gray matter & white matter. •These neurons are connected by trillions of connections called synapses, which allows for the transmission or passage of nerve impulses within the brain and to and from the pheripheral body.