Farmasevtika instituti farmakologiya va klinik farmatsiya kafedrasi

Higher Brain or Cortical Level 
After the preceding account of the many nervous system 
functions that occur at the cord and lower brain levels, one may ask, what is left for the cerebral cortex 
to do? The answer to this is complex, but it begins with the fact that the cerebral cortex is an extremely 
large memory storehouse. 
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.
Problem
t 
 
Physiologic Anatomy of the Synapse 
Figure 45-5 shows a typical 
anterior motor neuron 
in the anterior horn of the spinal cord. It is 
composed of three major parts: the 
soma, 
which is the main body of the neuron;a single 
axon, 
which 
extends fom the soma into a peripheral nerve that leaves the spinal cord; and the 
dendrites, 
which are 
great numbers of branching projections of the soma that extend as much as 1 millimeter into the 
surrounding areas of the cord

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