Neurons are structural and functional units of the nervous system. These are specialized to receive, conduct and respond to various stimuli. A neuron has three parts. The main body of a neuron is called a cyton, or cell body. Several finger-like projections branching out from the cyton are called dendrons. The axon is the longest single extension from the cyton. Its end is divided into branches that end in synaptic knobs. The point of contact between terminal branches of an axon and the dendrites of adjacent neurons is called a synapse. The nerve impulse from an axon of one neuron to the next neuron's dendrites passes through the synapse as a chemical message by neurotransmitters.

Neurons are structural and functional units of the nervous system. These are specialized to receive, conduct and respond to various stimuli. The myelin sheath is a coating of myelin on some neurons. In most neurons, axons are surrounded by a spirally coiled sheath of a fatty substance called a myelin sheath or medullated sheath. It is formed by the coiling of the plasma membrane of Schwann cells around the axon. The Myelin sheath insulates the axon. It also speeds up the nerve impulse. There is a constriction between the two Schwann cells. It is called the node of Ranvier. In medullated nerve fibers, the nerve impulse jumps from one node of Ranvier to the next.