Human central nervous system presentation. General physiology of the central nervous system. Classification of the nervous system

Reflex. Neuron. Synapse. The mechanism of excitation through the synapse

Prof. Mukhina I.V.

Lecture No. 6 Faculty of Medicine

CLASSIFICATION OF THE NERVOUS SYSTEM

Peripheral nervous system

Functions of the central nervous system:

1). Combination and coordination of all functions of tissues, organs and systems of the body.

2). Communication of the body with the external environment, regulation of body functions in accordance with its internal needs.

3). The basis of mental activity.

The main activity of the central nervous system is reflex

Rene Descartes (1596-1650) - pioneered the concept of reflex as a reflective activity;

Georg Prochaski (1749-1820);

THEM. Sechenov (1863) “Reflexes of the Brain,” in which he first proclaimed the thesis that all types of conscious and unconscious human life are reflex reactions.

A reflex (from Latin reflecto - reflection) is the body's response to irritation of receptors and carried out with the participation of the central nervous system.

The Sechenov-Pavlov reflex theory is based on three principles:

1. Structurality (the structural basis of the reflex is the reflex arc)

2. Determinism (principle cause-and-effect relationships). Not a single response of the body occurs without a reason.

3. Analysis and synthesis (any effect on the body is first analyzed and then summarized).

Morphologically consists of:

receptor formations, whose purpose is

V transformation of the energy of external stimuli (information)

V energy of a nerve impulse;

afferent (sensitive) neuron, conducts nerve impulses to the nerve center;

interneuron (interneuron) neuronor nerve center

representing the central part of the reflex arc;

efferent (motor) neuron, conducts the nerve impulse to the effector;

effector (working body),carrying out relevant activities.

The transmission of nerve impulses is carried out using neurotransmitters or neurotransmitters– chemical substances, released by nerve endings in

chemical synapse

LEVELS OF STUDY OF CNS FUNCTIONING

Organism

Neuron structure and function

Dendrites

Functions of neurons:

1. Integrative;

2. Coordinating

3. Trophic

			Purkinje cell
	Dendrites	Astrocyte	(cerebellum)	Pyramid
			Oligodendrocyte
				cortical neuron

General physiology
central nervous
systems
Lecture No. 2
for 2nd year students
Head department Shtanenko N.I.

Lecture outline:

Basic physiological properties
nerve centers.
Features of distribution
excitation in the central nervous system
Braking
V
CNS.
Nature
braking. Types of braking.
Reflex coordination mechanisms
activities

The third level of coordination is carried out in the process of activity of nerve centers and their interaction

Nerve centers are formed
combining several local
networks and represent
complex of elements capable
carry out a certain reflex
or behavioral act.
.

–
This
totality
neurons,
necessary for implementation
certain
reflex
or
regulation of a certain function.
M. Flourens (1842) and N. A. Mislavsky (1885)

is a complex structural and functional
Union
nervous
cells,
located at different levels
CNS and those providing due to them
integrative activity regulation
integral adaptive functions
(eg respiratory center in the broad sense of the word)

Classification of nerve centers (according to a number of characteristics)

Localizations (cortical, subcortical,
spinal);
Functions (respiratory,
vasomotor, heat generation);
Modalities of holistic
biological states (hunger, emotions, drives, etc.)

Unilateral conduction of excitation
Synaptic delay - slowing down
conducting excitation through the center 1.5-2 ms
Irradiation (divergence)
Convergence (animation)
Circulation (reverberation)
The main properties of nerve centers are determined by the characteristics of their
structure and presence of interneuron synaptic connections.

Reflex arc

Synaptic conduction delay

period temporarily required for:
1. excitation of receptors (receptors)
for conducting excitation impulses
along afferent fibers to the center;
3.
distribution
excitement
through
nerve centers;
4.
spreading
excitement
By
efferent fibers to the working organ;
2.
5. latent period of the working organ.

Reflex time Central reflex time

Reflex time
(latency period of the reflex) is
time from the moment of irritation to the end
effect. In a monosynaptic reflex it reaches 20-25 ms. This
time is spent on excitation of receptors, conducting excitation along
afferent fibers, transmission of excitation from afferent neurons to
efferent (possibly through several intercalary ones), conducting excitation
along efferent fibers and transmission of excitation from the efferent nerve to
effector
Central
time
reflex–
This
the period of time during which a nerve impulse is transmitted
by brain structures. In the case of a monosynaptic reflex arc, it
is approximately 1.5-2 ms - this is the time required for transmission
excitations at one synapse. Thus, the central time of the reflex
indirectly indicates the number of synaptic transmissions taking place in
this reflex. Central Time in polysynaptic reflexes
more than 3 ms. In general, polysynaptic reflexes are very widespread
distributed in the human body. Central reflex time
is the main component of the total reflex time.

Knee reflex

Examples of reflex arcs
Knee reflex
Monosynaptic. IN
as a result of a sharp
sprains
proprioceptors
quadriceps
extension occurs
shins
(- defensive
Reflex time
0.0196-0.0238sec.
alpha motor neurons
proprioceptive
motor
unconditional)
But: even the simplest reflexes do not work separately.
(Here: interaction with the inhibitory circuit of the antagonist muscle)

Mechanism of propagation of excitation in the central nervous system

Types of convergence of excitation on one neuron

Multisensory
Multibiological
Sensory-biological

Phenomena of convergence and divergence in the central nervous system. The principle of “common final path”

REVERBERATION
(circulation)

Inertia
Summation:
sequential(temporary)
spatial
Transformation of arousal
(rhythm and frequency)
Post-tetanic potentiation
(post-activation)

Time summation

Spatial summation

Summation in the central nervous system

Sequential
Temporary
summation
Spatial summation

Transformation of the rhythm of excitation

Rhythm transformation

Trigger Properties
axon hillock
Threshold 30 mV
Threshold 10 mV
Neuron body
Ek
Eo
Axon hillock
Ek
Eo
"At a gun shot
neuron responds
machine gun fire"

Rhythm transformation

50
A
50
A
?
50
IN
Phase relationships
incoming pulses
IN
A
100
IN
A
IN
(following
fall into
refractoriness
previous

Features of the propagation of excitation in the central nervous system

Central relief

A
1
At
irritation A
get excited
2 neurons (1,2)
2
IN
3
4
5
At
irritation B
get excited
2 neurons (5, 6)
6
Cells
peripheral
borders
For irritation A + B
excited 6
neurons (1, 2, 3, 4, 5, 6)
Cells
central
parts
neural pool

Central occlusion

A
1
When irritated A
excited 4
neuron (1,2,3,4)
2
3
When irritated B
excited 4
neuron (3, 4, 5, 6)
IN
4
5
6
Cells
central
parts
neural pool
BUT with combined stimulation A + B
4 neurons are excited (1, 2, 5, 6)

Occlusion phenomenon

3+3=6
4+4=8

Post-tetanic potentiation

Ca2+
Ca2+

Reverb circuit

High sensitivity centers
to a lack of oxygen and glucose
Selective sensitivity
to chemicals
Low lability and high fatigue
nerve centers
Tone of nerve centers
Plastic

Synaptic plasticity

This is a functional and morphological restructuring
synapse:
Increased plasticity: facilitation (presynaptic
nature, Ca++), potentiation (postsynaptic nature,
increased sensitivity of postsynaptic receptors Sensitization)
Decreased plasticity: depression (decreased
neurotransmitter stores in the presynaptic membrane)
– this is a mechanism for the development of habituation - habituation

Long-term forms of plasticity

Long-term potentiation - long-term
strengthening of synaptic transmission on
high-frequency irritation, may
continue for days and months. Characteristic for
all parts of the central nervous system (hippocampus, glutamatergic
synapses).
Long-term depression - long-term
weakening of synaptic transmission (low
intracellular Ca++ content)

active independent
physiological process
caused by excitement and
aimed at weakening
cessation or prevention
other excitement

Braking

Braking
Inhibition of nerve cells, centers -
parity in functionality
significance with excitement nervous
process.
But! Braking does not apply
it is “attached” to the synapses on which
inhibition occurs.
Inhibition controls excitation.

Braking functions

Limits the spread of excitation in the central nervous system, irradiation, reverberation, animation, etc.
Coordinates functions, i.e. directs arousal
along certain pathways to certain nerves
centers
Braking performs a protective or protective function.
role by protecting nerve cells from excessive
excitement and exhaustion during action
super-strong and prolonged irritants

Central braking was discovered by I.M. Sechenov in 1863

Central inhibition in the central nervous system (Sechenovsky)

Sechenov braking

Classification of inhibition in the central nervous system

Electrical state of the membrane
hyperpolarizing
depolarizing
Relation to synapse
postsynaptic
presynaptic
Neuronal organization
progressive,
returnable,
lateral

Bioelectric activity of a neuron

Brake mediators -

Brake mediators GAMK (gamma-aminobutyric acid)
Glycine
Taurine
The occurrence of IPSPs in response to afferent stimulation is obligatory
is associated with the inclusion in the inhibitory process of an additional link of the inhibitory interneuron, the axonal endings of which are distinguished
brake mediator.

Inhibitory postsynaptic potential IPSP

mv
0
4
6
8
ms
- 70
- 74
HYPERPOLARIZATION
K+ Clֿ

TYPES OF BRAKING

P E R V I C H N O E:
A) POSTSYNAPTIC
B) PRESYNAPTIC
SECONDARY:
A) PESSIMAL according to N. Vvedensky
B) TRACE (with trace hyperpolarization)
(Inhibition following excitation)

Ionic nature of postsynaptic inhibition

Postsynaptic inhibition (Latin post behind, after something + Greek sinapsis contact,
connection) is a nervous process caused by the action of specific substances on the postsynaptic membrane
inhibitory mediators secreted by specialized presynaptic nerve endings.
The transmitter released by them changes the properties of the postsynaptic membrane, which causes suppression
the cell's ability to generate excitation. This results in a short-term increase
permeability of the postsynaptic membrane to K+ or CI- ions, causing a decrease in its input
electrical resistance and generation of inhibitory postsynaptic potential (IPSP).

POSTSYNAPTIC INHIBITION

TO
Cl
GABA
TPSP

Braking mechanisms

Decreased membrane excitability in
as a result of hyperpolarization:
1. Release of potassium ions from the cell
2. Entry of chlorine ions into the cell
3. Reduced electrical density
current flowing through the axonal
mound as a result of activation
chlorine channels

Classification of species

I.
Primary postsynaptic
braking:
a) Central (Sechenov) inhibition.
b) Cortical
c) Reciprocal inhibition
d) Return braking
e) Lateral inhibition
Towards:
Direct.
Returnable.
Lateral.
Reciprocal.

MS, MR – flexor and extensor motor neurons.

Diagram of direct postsynaptic
braking in the segment spinal cord.
MS, MR – motor neurons
flexor and extensor.

Step reflex

Examples of reflex arcs
Step reflex
4- disinhibition
3
4
1
2
A. continuous
motor stimulation
CNS centers are broken down
for successive acts
excitement of the right and
left leg.
(reciprocal + reciprocal
oh braking)
B. motion control when
posture reflex
(reciprocal inhibition)

Reciprocal inhibition – at the level of spinal cord segments

INHIBITION IN THE CNS

BRAKING
Return braking
by Renshaw
B - excitement
T - braking
In the central nervous system
Lateral
braking

Reversible (antidromic) inhibition

Recurrent postsynaptic inhibition (Greek: antidromeo to run in the opposite direction) - process
regulation by nerve cells of the intensity of signals received by them according to the principle of negative feedback.
It lies in the fact that the axon collaterals of a nerve cell establish synaptic contacts with special
interneurons (Renshaw cells), whose role is to influence neurons converging on the cell,
sending these axon collaterals. According to this principle, motor neurons are inhibited.

Lateral inhibition

Synapses on a neuron

Presynaptic inhibition

It is carried out through special inhibitory interneurons.
Its structural basis is axo-axonal synapses,
formed by the axon terminals of inhibitory interneurons and
axonal endings of excitatory neurons.

PRESYNAPTIC
BRAKING
1 - axon of inhibitory neuron
2 - axon of excitatory neuron
3 - postsynaptic membrane
alpha moto neuron
Cl¯- channel
At the terminals of the presynaptic inhibitory
the axon releases a transmitter, which
causes depolarization of excitatory
endings
behind
check
increase
permeability of their membrane to CI-.
Depolarization
causes
decrease
amplitude of the action potential coming
into the excitatory axon terminal. IN
As a result, the process is inhibited
release of the neurotransmitter by excitatory
nervous
endings
And
decline
amplitudes
exciting
postsynaptic potential.
Characteristic feature
presynaptic depolarization is
slow development and long duration
(several hundred milliseconds), even after
single afferent impulse.

Presynaptic inhibition

Presynaptic inhibition primarily blocks weak
asynchronous afferent signals and transmits stronger,
therefore, it serves as a mechanism for isolating, isolating more
intense afferent impulses from the general flow. It has
enormous adaptive significance for the body, since of all
afferent signals going to the nerve centers, the most prominent
the main ones, the most necessary for this particular time.
Thanks to this, the nerve centers, the nervous system as a whole, are freed
from processing less essential information

Afferent impulses from the flexor muscle with the help of Renshaw cells cause presynaptic inhibition on the afferent nerve, which under

Presynaptic inhibition circuit
in a segment of the spinal cord.
Afferent
impulses from muscles
– flexor s
using cells
Renshaw is called
presynaptic
braking on
afferent nerve,
which fits
motor neuron
extensor

Examples of inhibition disorders in the central nervous system

IMPAIRMENT OF POSTSYNAPTIC INHIBITION:
STRYCHNINE - BLOCKING OF RECEPTORS OF INHIBITORY SYNAPSES
TETANUS TOXIN - RELEASE DISORDER
BRAKE MEDIATOR
IMPAIRMENT OF PRESYNAPTIC INHIBITION:
PICROTOXIN - BLOCKING PRESYNAPTIC SYNAPSES
Strychnine and tetanus toxin have no effect on it.

Postsynaptic reentrant inhibition. Blocked by strychnine.

Presynaptic inhibition. Blocked by picrotoxin

Classification of species

Secondary braking is not associated with
inhibitory structures is
consequence of previous
excitement.
a) Transcendent
b) Pessimal inhibition of Vvednsky
c) Parobiotic
d) Inhibition following excitation

Induction

By the nature of the influence:
Positive - observed when braking is replaced
increased excitability around you.
Negative - if the focus of excitation is replaced by inhibition
By time:
Simultaneous Positive simultaneous induction
observed when inhibition immediately (simultaneously) creates a state
increased excitability around you.
Sequential When changing the braking process to
excitation – positive sequential induction

Registration of EPSPs and IPSPs

PRINCIPLES OF COORDINATION OF REFLEX ACTIVITY

1. RECIPROCITY
2. COMMON FINAL PATH
(according to Sherrington)
3. DOMINANTS
4. SUBORDINATION OF NERVOUS CENTRAL DETERMINATION OF DOMINANT
(According to A.A. Ukhtomsky, 1931)
temporarily
dominant
hearth
excitement
V
central
nervous system, determining
current activity of the body
DOMINANT
-

DEFINITION OF DOMINANCE
(According to A.A. Ukhtomsky, 1931)
temporarily
dominant
reflex
or
behavioral
Act,
which
transformed and directed
for a given time with other
equal conditions of work for others
reflex arcs, reflex
apparatus and behavior in general
DOMINANT
-

PRINCIPLE OF DOMINANCE
Irritants
Nerve centers
Reflexes

The main signs of a dominant
(according to A.A. Ukhtomsky)
1. Increased excitability of the dominant
center
2. Persistence of excitation in the dominant
center
3. The ability to summarize excitations,
thereby reinforcing your excitement
extraneous impulses
4. Ability to slow down other current
reflexes on a common final path
5. Inertia of the dominant center
6. Ability to disinhibit

Scheme of formation of dominant D - persistent excitation - grasping reflex in a frog (dominant), caused by the application of strychnine. All

D
Dominant formation scheme
D – persistent excitation of the grasping reflex
frogs (dominant),
caused by application
strychnine. All irritations in
points 1,2,3,4 do not give answers,
but only increase activity
neurons D.

Inhibition is an independent nervous process that is caused by excitation and manifests itself in the suppression of other excitation.

• Inhibition is an independent nervous process that is caused by excitation and manifests itself in the suppression of other excitation.

History of discovery

• 1862 - discovery by I.M. Sechenov effect of central inhibition (chemical irritation of the visual thalamus of the frog inhibits simple spinal unconditioned reflexes);
• The beginning of the 20th century - Eccles and Renshaw showed the existence of special inhibitory intercalary neurons that have synaptic contacts with motor neurons.

Central braking mechanisms

• Depending from neural mechanism, distinguish between primary inhibition, carried out via inhibitory neurons And secondary inhibition, carried out without the help of inhibitory neurons.

• Primary inhibition:
• Postsynaptic;
• Presynaptic.
• Secondary braking
• 1. Pessimal;
• 2. Post-activation.

Postsynaptic inhibition

• - the main type of inhibition that develops in the postsynaptic membrane of axosomatic and axodendritic synapses under the influence of activation inhibitory neurons, from the presynaptic endings of which it is released and enters the synaptic cleft brake mediator(glycine, GABA).

• The inhibitory transmitter causes an increase in permeability for K+ and Cl- in the postsynaptic membrane, which leads to hyperpolarization in the form of inhibitory postsynaptic potentials (IPSPs), the spatiotemporal summation of which increases the level of membrane potential, reducing the excitability of the postsynaptic cell membrane. This leads to the cessation of the generation of propagating APs in the axonal hillock.
• Thus, postsynaptic inhibition is associated with decreased excitability of the postsynaptic membrane.

Presynaptic inhibition

• Depolarization of the postsynaptic region causes a decrease in the amplitude of the AP arriving at the presynaptic ending of the excitatory neuron (the “barrier” mechanism). It is assumed that the decrease in excitability of the excitatory axon during prolonged depolarization is based on the processes of cathodic depression (the critical level of depolarization changes due to inactivation of Na + channels, which leads to an increase in the depolarization threshold and a decrease in axon excitability at the presynaptic level).
• A decrease in the amplitude of the presynaptic potential leads to a decrease in the amount of released transmitter up to the complete cessation of its release. As a result, the impulse is not transmitted to the postsynaptic membrane of the neuron.
• The advantage of presynaptic inhibition is its selectivity: in this case, individual inputs to the nerve cell are inhibited, while with postsynaptic inhibition the excitability of the entire neuron as a whole decreases.

• Develops in axoaxonal synapses, blocking the spread of excitation along the axon. Often found in stem structures, in the spinal cord, and in sensory systems.
• Impulses at the presynaptic terminal of the axoaxonal synapse release a neurotransmitter (GABA), which causes long-term depolarization postsynaptic region by increasing the permeability of their membrane to Cl-.

Pessimal inhibition

• Represents a type of braking central neurons.
• Occurs with high frequency of irritation. . It is assumed that the underlying mechanism is the inactivation of Na channels during prolonged depolarization and the change in membrane properties is similar to cathodic depression. (Example - a frog turned on its back - powerful afferentation from vestibular receptors - the phenomenon of numbness, hypnosis).

• Does not require special structures. Inhibition is caused by a pronounced trace hyperpolarization of the postsynaptic membrane in the axonal hillock after prolonged excitation.

• Post-activation inhibition

Depending on the structure of neural networks differentiate three types braking:

• Returnable;
• Reciprocal (conjugate);
• Lateral.

Return braking

• Inhibition of neuron activity caused by the recurrent collateral of the axon of a nerve cell with the participation of an inhibitory interneuron.
• For example, a motor neuron in the anterior horn of the spinal cord gives off a lateral collateral that returns back and ends on inhibitory neurons - Renshaw cells. The Renshaw cell axon ends on the same motor neuron, exerting an inhibitory effect on it (feedback principle).

Reciprocal (conjugate) inhibition

• The coordinated work of antagonistic nerve centers is ensured by the formation of reciprocal relationships between nerve centers due to the presence of special inhibitory neurons - Renshaw cells.
• It is known that flexion and extension of the limbs is carried out due to the coordinated work of two functionally antagonistic muscles: flexors and extensors. The signal from the afferent link through the interneuron causes excitation of the motor neuron innervating the flexor muscle, and through the Renshaw cell inhibits the motor neuron innervating the extensor muscle (and vice versa).

Lateral inhibition

• With lateral inhibition, excitation transmitted through the axon collaterals of the excited nerve cell activates intercalary inhibitory neurons, which inhibit the activity of neighboring neurons in which excitation is absent or weaker.
• As a result, very deep inhibition develops in these neighboring cells. The resulting inhibition zone is located laterally in relation to the excited neuron.
• Lateral inhibition according to the neural mechanism of action can take the form of both postsynaptic and presynaptic inhibition. Plays an important role in identifying features in sensory systems and the cerebral cortex.

Braking value

• Coordination of reflex acts. Directs excitation to certain nerve centers or along a certain path, turning off those neurons and paths whose activity is in this moment is insignificant. The result of such coordination is a certain adaptive reaction.
• Irradiation limitation.
• Protective. Protects nerve cells from overexcitation and exhaustion. Especially under the influence of super-strong and long-acting irritants.

Coordination

• In the implementation of the information-control function of the central nervous system, a significant role belongs to processes coordination activity of individual nerve cells and nerve centers.
• Coordination– morphofunctional interaction of nerve centers aimed at implementing a certain reflex or regulating a function.
• Morphological basis of coordination: connection between nerve centers (convergence, divergence, circulation).
• Functional basis: excitation and inhibition.

Basic principles of coordination interaction

• Conjugate (reciprocal) inhibition.
• Feedback. Positive– signals arriving at the system input via the feedback circuit act in the same direction as the main signals, which leads to increased mismatch in the system. Negative– signals arriving at the system input via the feedback circuit act in the opposite direction and are aimed at eliminating the mismatch, i.e. deviations of parameters from a given program ( PC. Anokhin).
• General final path (funnel principle) Sherrington). The convergence of nerve signals at the level of the efferent link of the reflex arc determines physiological mechanism the principle of a “common final path”.
• Facilitation. This is an integrative interaction of nerve centers, in which the total reaction with simultaneous stimulation of the receptive fields of two reflexes is higher than the sum of reactions with isolated stimulation of these receptive fields.
• Occlusion. This is an integrative interaction of nerve centers, in which the total reaction with simultaneous stimulation of the receptive fields of two reflexes is less than the sum of reactions with isolated stimulation of each of the receptive fields.
• Dominant. Dominant is called a focus (or dominant center) of increased excitability in the central nervous system that is temporarily dominant in the nerve centers. By A.A. Ukhtomsky, the dominant focus is characterized by:
• - increased excitability,
• - persistence and inertia of excitation,
• - increased summation of excitation.
• The dominant significance of such a focus determines its inhibitory effect on other neighboring centers of excitation. The principle of dominance determines the formation of the dominant excited nerve center in close accordance with the leading motives and needs of the body at a particular moment in time.
• 7. Subordination. Ascending influences are predominantly of an exciting stimulating nature, while descending influences are of a depressing inhibitory nature. This scheme is consistent with the ideas about growth in the process of evolution, the role and significance of inhibitory processes in the implementation of complex integrative reflex reactions. Has a regulatory nature.

Questions for students

• 1. Name the main inhibitory mediators;
• 2. What type of synapse is involved in presynaptic inhibition?;
• 3. What is the role of inhibition in the coordination activity of the central nervous system?
• 4. List the properties of the dominant focus in the central nervous system.

Slide 2

The nervous system is divided into the central nervous system and the peripheral nervous system. Brain CNS Spinal cord Peripheral nervous system: - nerve fibers, ganglia.

Slide 3

The central nervous system carries out: 1. Individual adaptation of the body to the external environment. 2. Integrative and coordinating functions. 3. Forms goal-oriented behavior. 4. Performs analysis and synthesis of received stimuli. 5. Forms a flow of efferent impulses. 6. Maintains the tone of body systems. The modern concept of the central nervous system is based on the neural theory.

Slide 4

CNS is a collection of nerve cells or neurons. Neuron. Sizes from 3 to 130 microns. All neurons, regardless of size, consist of: 1. Body (soma). 2. Axon dendrites

Structural and functional elements of the central nervous system. The cluster of neuron bodies makes up the gray matter of the central nervous system, and the cluster of processes makes up the white matter.

Slide 5

Each element of the cell performs a specific function: The body of the neuron contains various intracellular organelles and ensures the life of the cell. The body membrane is covered with synapses, therefore it perceives and integrates impulses coming from other neurons. Axon (long process) - conducts a nerve impulse from the body of the nerve cell and to the periphery or to other neurons. Dendrites (short, branching) - perceive irritations and communicate between nerve cells.

Slide 6

1. Depending on the number of processes, they are distinguished: - unipolar - one process (in the nuclei of the trigeminal nerve) - bipolar - one axon and one dendrite - multipolar - several dendrites and one axon2. In functional terms: - afferent or receptor - (receive signals from receptors and conduct them to the central nervous system) - intercalary - provide communication between afferent and efferent neurons. - efferent - conduct impulses from the central nervous system to the periphery. They are of 2 types: motor neurons and efferent neurons of the VNS - excitatory - inhibitory

CLASSIFICATION OF NEURONS

Slide 7

The relationship between neurons is carried out through synapses.

1. Presynaptic membrane 2. Synaptic cleft 3. Postsynaptic membrane with receptors. Receptors: cholinergic receptors (M and N cholinergic receptors), adrenergic receptors - α and β Axonal hillock (axon expansion)

Slide 8

CLASSIFICATION OF SYNAPSES:

1. By location: - axoaxonal - axodendritic - neuromuscular - dendrodendritic - axosomatic 2. By the nature of the action: excitatory and inhibitory. 3. By signal transmission method: - electrical - chemical - mixed

Slide 9

The transmission of excitation in chemical synapses occurs due to mediators, which are of 2 types - excitatory and inhibitory. Exciting agents - acetylcholine, adrenaline, serotonin, dopamine. Inhibitory – gamma-aminobutyric acid (GABA), glycine, histamine, β-alanine, etc.

Mechanism of excitation transmission in chemical synapses

Slide 10

The mechanism of excitation transmission in the excitatory synapse (chemical synapse): impulse → nerve ending into synaptic plaques → depolarization of the presynaptic membrane (Ca++ input and transmitter output) → mediators → synaptic cleft → postsynaptic membrane (interaction with receptors) → generation of EPSP → AP.

Slide 11

In inhibitory synapses, the mechanism is the following impulse → depolarization of the presynaptic membrane → release of the inhibitory transmitter → hyperpolarization of the postsynaptic membrane (due to K+) → IPSP.

Slide 12

In chemical synapses, excitation is transmitted using mediators. Chemical synapses have one-way conduction of excitation. Fatigue (depletion of neurotransmitter reserves). Low lability 100-125 pulses/sec. Summation of excitation Blazing a path Synaptic delay (0.2-0.5 m/s). Selective sensitivity to pharmacological and biological substances. Chemical synapses are sensitive to temperature changes. There is trace depolarization at chemical synapses. PHYSIOLOGICAL PROPERTIES OF CHEMICAL SYNAPSES

Slide 13

Physiological properties of electrical synapses (effapses).

Electrical transmission of excitation Bilateral conduction of excitation High lability No synaptic delay Only excitatory.

Slide 14

REFLECTOR PRINCIPLE OF REGULATION OF FUNCTION

The activity of the body is a natural reflex reaction to a stimulus. In the development of reflex theory, the following periods are distinguished: 1. Descartes (16th century) 2. Sechenovsky 3. Pavlovsky 4. Modern, neurocybernetic.

Slide 15

METHODS OF RESEARCH OF THE CNS

Extirpation (removal: partial, complete) Irritation (electrical, chemical) Radioisotope Modeling (physical, mathematical, conceptual) EEG (recording of electrical potentials) Stereotactic technique. Development of conditioned reflexes Computed tomography Pathoanatomical method

View all slides

summary of other presentations

“Fundamentals of higher nervous activity” - Internal inhibition. Reflexes. Paradoxical dream. External braking. Insight. Neural connection. Sequence of elements of a reflex arc. Choleric temperament. Formation of a conditioned reflex. Dream. Acquired by the body during life. Congenital reflexes. Creation of the doctrine of GNI. Wakefulness. Human children. Sanguine temperament. Type of internal braking. Correct judgments.

“Autonomic division of the nervous system” - Pilomotor reflex. Raynaud's disease. Pharmacological tests. Parasympathetic part of the autonomic nervous system. Functions internal organs. Test with pilocarpine. Solar reflex. Limbic system. Bulbar department. The sympathetic part of the autonomic nervous system. Bernard's syndrome. Features of autonomic innervation. Damage to the autonomic ganglia of the face. Sacral department. Cold test. Sympathotonic crises.

“Evolution of the nervous system” - Class Mammals. Diencephalon. Nervous system of vertebrates. Shellfish. Pisces class. Medulla oblongata (hind) brain. Anterior section. Evolution of the nervous system. Cerebellum. Bird class. Reflex. Class Amphibians. Neuron. The nervous system is a collection of various structures of nervous tissue. Evolution of the nervous system of vertebrates. Divisions of the brain. Cells of the body. Nerve tissue is a collection of nerve cells.

“The work of the human nervous system” - Ivan Petrovich Pavlov. Sechenov Ivan Mikhailovich. Reflex arc. Reflex principle of the nervous system. Active state of neurons. Comparison of unconditioned and conditioned reflexes. The concept of reflex. M. Gorky. Find a match. Knee reflex.

“Physiology of VND” - Physiology of higher nervous activity. Decreased metabolic activity. Cochlear implant. Connecting neurons. Patient. Global working space. Vegetative state. Psychophysiological problem. Flexibility of modules. Modern neurophysiological theories of consciousness. Creating a global workspace. A variety of different states of consciousness. The problem of consciousness in cognitive science.

“Features of human higher nervous activity” - Unconditional inhibition. Classification of conditioned reflexes. Development of a conditioned reflex. Features of human higher nervous activity. Formation of a temporary connection. Types of inhibition of mental activity. The dog eats from a bowl. Unconditioned reflexes. Insight. Reflexes. Conditioned reflexes. Saliva is produced. Brain functions. Fistula for collecting saliva. Types of instincts. Basic characteristics of a conditioned reflex.