ABSTRACT
Nerve cells consist of a cell body with numerous projections of the plasma membrane, called dendrites. These interact with other cells and receive information from them in the form of nerve impulses. The cell body then assimilates the information derived from a number of dendritric contacts and passes on the information as another nerve impulse down the large axon. The end of the axon, the nerve terminal, is full of synaptic vesicles that store the chemical neuro-transmitters, such as acetylcholine. The action potential arises from large, transient changes in the permeability of the plasma membrane of the neuron to Na+ and K+ ions. 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 over 30 substances as neurotransmitters.
