ABSTRACT
Nerve cells, or neurons, consist of a cell body from which the dendrites and axon extend. The dendrites receive information from other cells; the axon passes this information on to another cell, the post-synaptic cell. The axon is covered in a myelin membranous sheath except at the nodes of Ranvier. The axon ends at the nerve terminal where chemical neurotransmitters are stored in synaptic vesicles for release into the synaptic cleft. An electric potential exists across the plasma membrane of all cells. Most cells are electrically inactive as this membrane potential does not vary with time. However, neurons and muscle cells are electrically active as their membrane potential can vary with time. When the action potential reaches the nerve terminal it causes the release of a chemical neurotransmitter from the synaptic vesicles. The mammalian nervous system employs numerous substances as neurotransmitters.
