86
2 Holographic Microscopy of Phase and Diffuse Objects …
But neuron has its own characteristic masses of nerve cells concerning directly its
function. The main function of a neuron is to get information, process it and hand it
further. For this purpose, neuron has a lot of dendrites (Fig. 2.9), which are used for
handing the information to the cell and one axon, the length of which can be several
meters: Through it, the information leaves the neuron and hands further over the
nervous system. At some distance from the cell body, axon branches send its processes
to other nerve cells and to the dendrites. Each process ends with special thickness—
synaptic patch filled with vesicles, which preserve different chemicals—mediators.
They provide communication between neurons.
Nerve impulses, which leave neurons and transmit through axon, are specific
electric signals. Axon itself can be compared with electric conductor, the central
part of which is formed by nerve fibers and covered with insulation—medullary
sheath. It provides a high speed of electric pulse through nerve fiber isolating it from
electrochemical influence of other nerve fibers.
Electric pulse moving through the axon reaches the synaptic patch and starts there
chemical reactions. As a result, mediators are released and thrown into the synaptic
gap (microspace which dividing two membranes into synaptic and postsynaptic).
Mediator molecules interact with receptors built-in in the postsynaptic membrane,
and due to this, channels for potassium and sodium ions are opened in the cell.
Occurred intensive flow of ions excites the cell and generates there electric pulse,
which is passed to the following neuron, etc.
But this process is not infinite. If the excitation began to pass through the whole
channels of interneural connection, such a chain reaction would result in the disorganization of the brain and even could cause death. It does not happen because along
with the excitation, there exists deceleration. The specialists are persistently trying
to understand the essence of deceleration, as the role of retarding pulses in the functioning of the brain is as important as excitation pulses. When deceleration processes
are damaged and neurons begin “to talk” simultaneously and continuously, it causes
the development of one and other mental insanities.
By studying complex mechanisms of nerve pulsing, the specialists determined
that the number of branches of neuron processes changes through life due to what
the brain is growing and developing. After all, the mature nerve cell is not capable
of division and cannot reproduce. Those 10–14 milliards of neurons (as different
authors say), which are formed by the birth of a child, does not increase anymore.
But the number of dendrites as well as the number of axon branches is constantly
changing. The most intensive growth of these elements takes place during the first
5–7 years. Accordingly, the number of neurons synaptic connections is also growing;
according to the studies of the specialists, 80% of nerve cell surface can be covered
with synapsis.
During last years, the scientists found out a lot of new information about the
organization of interneural connection. In particular, they detected that the number
of synapsis testifying to the number of neuron connections varies in different nerve
cells.
Not long ago, it has been considered that synaptic connection exists only between
axon of one neuron and its branches, and the body or dendrites of the other. Using
2 Holographic Microscopy of Phase and Diffuse Objects …
But neuron has its own characteristic masses of nerve cells concerning directly its
function. The main function of a neuron is to get information, process it and hand it
further. For this purpose, neuron has a lot of dendrites (Fig. 2.9), which are used for
handing the information to the cell and one axon, the length of which can be several
meters: Through it, the information leaves the neuron and hands further over the
nervous system. At some distance from the cell body, axon branches send its processes
to other nerve cells and to the dendrites. Each process ends with special thickness—
synaptic patch filled with vesicles, which preserve different chemicals—mediators.
They provide communication between neurons.
Nerve impulses, which leave neurons and transmit through axon, are specific
electric signals. Axon itself can be compared with electric conductor, the central
part of which is formed by nerve fibers and covered with insulation—medullary
sheath. It provides a high speed of electric pulse through nerve fiber isolating it from
electrochemical influence of other nerve fibers.
Electric pulse moving through the axon reaches the synaptic patch and starts there
chemical reactions. As a result, mediators are released and thrown into the synaptic
gap (microspace which dividing two membranes into synaptic and postsynaptic).
Mediator molecules interact with receptors built-in in the postsynaptic membrane,
and due to this, channels for potassium and sodium ions are opened in the cell.
Occurred intensive flow of ions excites the cell and generates there electric pulse,
which is passed to the following neuron, etc.
But this process is not infinite. If the excitation began to pass through the whole
channels of interneural connection, such a chain reaction would result in the disorganization of the brain and even could cause death. It does not happen because along
with the excitation, there exists deceleration. The specialists are persistently trying
to understand the essence of deceleration, as the role of retarding pulses in the functioning of the brain is as important as excitation pulses. When deceleration processes
are damaged and neurons begin “to talk” simultaneously and continuously, it causes
the development of one and other mental insanities.
By studying complex mechanisms of nerve pulsing, the specialists determined
that the number of branches of neuron processes changes through life due to what
the brain is growing and developing. After all, the mature nerve cell is not capable
of division and cannot reproduce. Those 10–14 milliards of neurons (as different
authors say), which are formed by the birth of a child, does not increase anymore.
But the number of dendrites as well as the number of axon branches is constantly
changing. The most intensive growth of these elements takes place during the first
5–7 years. Accordingly, the number of neurons synaptic connections is also growing;
according to the studies of the specialists, 80% of nerve cell surface can be covered
with synapsis.
During last years, the scientists found out a lot of new information about the
organization of interneural connection. In particular, they detected that the number
of synapsis testifying to the number of neuron connections varies in different nerve
cells.
Not long ago, it has been considered that synaptic connection exists only between
axon of one neuron and its branches, and the body or dendrites of the other. Using