Comparison of the Nervous System with a Computer When computers were first developed, it soon became apparent that these
machines have many features in common with the nervous system. First, all computers have input
circuits that are comparable to the sensory portion of the nervous system, as well as output circuits that
arecomparable to the motor portion of the nervous system.
Types of Synapses — Chemical and Electrical There are two major types of synapses: (1)
the chemical synapse and (2) the electrical synapse. Almost all the synapses used for signal
transmission in the central nervous system of the human being are chemical synapses. In these, the first neuron secretes at its nerve ending synapse a chemical substance called
a neurotransmitter (or often called simply transmitter substance), and this transmitter in turn acts on
receptor proteins in the membrane of the next neuron to excite the neuron, inhibit it, or modify its
sensitivity in some other way.
