The nervous system is made up of long chains of neurons. A neuron is made up of a soma (cell body), which is the central part of the nerve cell. Axons and dendrites are fibers that branch off from the cell body. Dendrites are at one end of the neuron and receive incoming messages from other neurons. Axons branch out at the other end of the neuron and carry messages away from the cell body, transmitting these messages to the next neuron. The axons are insulated with a protective coating called the myelin sheath. The myelin sheath is a white fatty substance which insulates the axons and accelerates the transmission of neural messages. A chemical connection, known as the synapse, bridges the gap between two neurons. Neurotransmitters carry chemical messages across the synapse to the dendrite of a receiver neuron. Thus, neural energy is transmitted from one neuron to another, enabling it to travel from the sensory receptor site to the brain.