Myelinated fibers conduct nerve impulses more rapidly than unmyelinated fibers. Myelin sheaths are produced by specialized neuroglia. The myelin sheath consists of several Schwann cells wrapped around the nerve fiber, with a node of Ranvier between each Schwann cell. 17.5, PAGE 524. Association neurons are the neurons that integrate incoming information from the sensory neurons and relay the response to the motor neurons.
Multipolar neurons are the most common type of neuron in the body.
The single process divides into an axon and a dendrite. The trigger zone is at the junction between the dendrite and axon. 17.5, page 524. It usually refers to an axon, but sometimes may be a dendrite. We will discuss them later when we look at the brain and spinal cord.