A neuron is a nerve cell. The brain is made up of about 100 billion neurons. Neurons have a nucleus that contains genes. Neurons have specialized projections called dendrites and axons . Dendrites bring information to the cell body and axons take information away from the cell body.
Neurons communicate with each other through an electrochemical process.
It has been estimated that there are 1 quadrillion synapses in the human brain. This is equal to about a half-billion synapses per cubic millimeter. We use all of our brain. A newborn human brain weighs between 350 and 400 g. The picture to the right is a human brain.