Neurons

The brain is made up of billions of nerve cells, called neurons. There are over 100 million neurons per square inch of your brain! Neurons communicate to nearby neighbors via electrical and chemical signals sent between axons and dendrites.

An axon is a long slender projection from a neuron which transmits signals away from the cell and towards other nearby neurons. Bundles of axons make up nerves and are the primary way that signals are transmitted throughout the body. The axons in your spinal cord can be as long as 3 feet.

A dendrite is a projection from a neuron that receives signals from the axons of its neighbors. A neuron will have a large number of dendrites but only one axon.

The interface between a dendrite and an axon is called a synapse. The signal is transmitted along the axon as an electrical impulse. Once it reaches the synapse, the release of chemical neurotransmitters transmits the signal to the dendrites of other neurons. Each neuron will be have between 1,000 and 10,000 synapses.