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1. Nervous system
The main regulation
mechanism of organism's
functions

2. Questions
Neuron
The reflex arc
The nervous centers
Properties of the nervous centers
The general principles of coordination
Inhibition in the CNS
Spinal cord
2

3. 3
Classification according to a structure and
function:

4. 4
Nervous system
Grey matter White matter
Neuron bodies Processes of nervous cells

5. 5
Neuron is structural and a functional
unit of nervous system

6. 6
Classification of neurons:

7. 7
Classification of
neurons by function
neurons
Sensory (afferent)
neurons
transmit impulses
from skin and other
sensory organs
or from various
places of the
body to the CNS
Contact (intercalary,
association) neurons
provide
communication
between neurons.
Motor (efferent)
neurons
transmit impulses
from the
CNS to effectors
(muscles or glands)

8. 8
Perception of external and internal stimuli, the
organization of corresponding adaptive reactions.
The nervous system provides the behavior organization.
Nervous system integrates and monitors the countless
actions occurring simultaneously throughout the entire
human body.
NS is a material basis of mental activity. There are
speech, thinking, consciousness.
Functions of the nervous system

9. 9
Reflex arch
Simple
Monosynaptic
Complex
Polysynaptic
(with contact neurons)
Reflex - the basic form nervous activity. The
answer of an organism to a boring of
receptors with the assistance of a CNS.
A reflex arc is the neural pathway that
mediates a reflex action.

10. 10
Reflex arch consists of 5 main parts

11. 11
1. The receptor perceives a irritation,
transforms energy of a irritation into energy
of nervous impulse.
The receptor
exteroreceptors interoreceptors proprioreceptors
senses by which
we perceive
the outside world
(receptors of a skin, eye,
ear, nasal cavity, etc.)
senses, by which we
perceive the pain
and movement
of internal organs
(receptors of vessels,
internal organs)
react to change
of body parts
position
in space
(receptors of muscles,
ligaments, tendons)

12. 12
2.An afferent a nervous way - processes
of receptor neurons which transfer the
information to the nervous center.
3.The reflex (nervous) center (is located
in the CNS) - group of neurons, which
transfer nervous impulses from afferent
to efferent nervous way
4.An efferent a nervous way – transfer
the information to an effektor.
5. An effektor – organ, which can answer
the impulses. The impulse causes
changes of its activity .

13. The nervous center is:
Anatomic definition: the anatomic
clump of the neurons are located in
certain department of a CNS.
Physiological definition: functional
association of the several (anatomic)
centers are located at different levels
of a CNS, which provide difficult
reflex acts (digestion, breathing, etc.)
The nervous centers

14. 14
Properties of the nervous centers depend on
mechanisms of conduction of excitation in synapses
1. One-sited conduction of excitation. It is transferring of
impulse from receptor neuron to effector. It is caused by
presence of synaptic transfer of excitation where it is possible
only in one site (from presynaptic to a postsynaptic membrane).
2. The delay of conduction of excitation – it is caused by
presence of a considerable quantity of synapses, mediator
releasing, diffusion through synaptic cleft. Excitation of a
postsynaptic membrane demands time – it is called “synaptic
delay"
3. Summation of excitation (subliminal stimulus are summated):
 summation in time - numerous irritation of receptor by subliminal
stimulus causes a reflex.
 spatial summation - irritation of receptors of reflex zones by
subliminal stimulus at the same time.

15. 15
4. Transformation of rhythm excitation – capacity of
nervous center exchange rhythm of impulses, that transfer from
afferent ways;
5. Afteraction of excitation – circulation of impulses on
chains of nervous center;
6. Fatigue of nervous center – efficiency decreasing, this is
due to disorder of synaptic transmission, attrition of mediator`s
pull and depression of receptors sensitivity to a mediator
(adaptation);
7. The tonus of the nervous centers – is supported by an
afteraction of excitation by afferent impulses, humoral influences
8. Plasticity of the nervous centers – ability to change
characteristic function for them (dysfunction of brain's parts are
provided by other centers)

16. 16
The general principles of coordination
Function of organism
Coordination - interaction of nervous processes in the CNS,
referred on association (integration) of organs` functions
and systems.
1. Morphological principles depend on
features of a structure of nervous system
2. Functional principles depend on functions
of nervous system

17. 17
Divergence principle –
neurons are capable to
form numerous synaptic
communications with other
neurons from which there
is a redistribution of
impulses.
Morphological principles

18. 18
Convergence
principle – concentration
of excitation from different
neurons to one.
Morphological principles

19. 19
Principle of the
general final way -
afferent fibers
converge on the same
intercalary efferent
neurons.
Feedback principle –
control of accuracy of
impellent reflexes.
Morphological principles

20. 20
1.Irradiation of excitation (diffusion) –
long strong excitation causes excitation
of many nervous centers.
2.Concentration of excitation.
3.Induction – excitation of the certain
nervous center leads to opposite process
– inhibition of the center bound to it.
Functional principles

21. 21
Dominant principle – separated strong excited
center inhibits all other centers.

22. 22
Inhibition in CNS
Is active nervous process, form of the response to a influence which
is manifested by inhibition or excitation decreasing
Inhibition types
According to connection
with inhibitory neurons
As consequence
of excitation
presynaptic postsynaptic The return pessimal

23. 23
Presynaptic inhibition
Development of a slow and
long depolarization of the
presynaptic termination of
excitable neuron is inhibited
by neurotransmitter –
blockade of carrying out of
excitation

24. 24
Postsynaptic inhibition
Postsynaptic membrane is
inhibited by
neurotransmitter

25. 25
The return inhibition - Oppression of
activity of neuron by a return collateral of
an axon.
Pessimal inhibition - A high frequency of
a stimulation of the neuron causes an
inhibition after excitation

26. 26
Value of inhibition
 The organism adaptation to
environment
 Remission of the CNS of processing of
the insignificant information;
 Coordination of motor reactions;
 Protection of the nervous centers from
fatigue and attrition

27. 27
Structure
of spinal
cord

28. Spinal cord
 The spinal cord is the most important structure between the body and the
brain. The spinal cord extends from the foramen magnum where it is
continuous with the medulla to the level of the first or second lumbar
vertebrae. It is a vital link between the brain and the body, and from the
body to the brain. The spinal cord is 40 to 50 cm long and 1 cm to 1.5 cm in
diameter. Two consecutive rows of nerve roots emerge on each of its sides.
These nerve roots join distally to form 31 pairs of spinal nerves. These
nerves are divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1
coccygeal nerve. The spinal nerve contains motor and sensory nerve fibers
to and from all parts of the body. The spinal cord is a cylindrical structure of
nervous tissue composed of white and gray matter.
 The gray matter contains the nerve cell bodies and all of the many
thousands of connections between nerves. The white matter is more like a
freeway composed of nerve axon fibers traveling long distances from the
spine to the brain. The ventral root carries motor axon fibers from cells in
the gray matter out to the muscles. Incoming sensory signals pass through
a connection - or synapse – in the dorsal root ganglion, and then follow the
dorsal root into the grey matter.
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29. 29
Segment
and
covers of
spinal
cord

30. 30
Spinal cord covers
The cord is sheathed in the same three connective tissue
meninges as is the brain: the pia (vasculosa),
arachnoid (serosa) and dura (fibrosa). The dura is the
tough outer sheath, the arachnoid lies beneath it, and
the pia closely adheres to the surface of the cord,
blood vessels are located in there
Cerebrospinal fluid (CSF) is located between it and
pia mater (vascular).

31. 31
Grey
matter is
White
matter is
Contact
neurons
Body and dendrites
of motor (efferent)
neurons
Axons of neurons,
which form:
descending (motor)
tracts
ascending (sensory)
tracts
Spinal cord

32. 32
Reflex function –
participation in
impellent reactions
Conduction –
transfering of
nervous impulses
Reflexes of muscles of antagonists:
reduction flexor oppression of a tonus of
extensors
Rhythmic reflexes: alternate action flexor
and extensors of extremities (walking, run)
Tonic reflexes – maintenance of position of
a body in space (a long strain of muscles)
Vegetative reflexes – regulation of work of
an internal, vessels, muscles
• Connection of different
departments of spinal cord;
• Connection of brain with
other department of CNS;
• Поєднання receptors with
виконавчими organs.
Functions of spinal cord