Presentation on the topic central nervous system. Presentation "Physiology of the central nervous system (CNS): inhibition"
TOPIC: CENTRAL NERVOUS SYSTEM (CNS) PLAN: 1. The role of the CNS in the integrative, adaptive activity of the body. 2. Neuron - as a structural and functional unit of the central nervous system. 3. Synapses, structure, functions. 4. Reflex principle of regulation of functions. 5. History of the development of reflex theory. 6.Methods for studying the central nervous system.
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.
The central nervous system 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 dendritic processes 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.
Each cell element performs a specific function: The neuron body 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 a nerve cell and to the periphery or to other neurons. Dendrites (short, branching) - perceive irritations and communicate between nerve cells.
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 axon 2. In functional terms: - afferent or receptor - (perceive signals from receptors and carried 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 ANS - excitatory - inhibitory CLASSIFICATION OF NEURONS
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 extension)
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
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
The mechanism of excitation transmission in the excitatory synapse (chemical synapse): impulse, nerve ending into synaptic plaques, depolarization of the presynaptic membrane (input of Ca++ and output of transmitters), neurotransmitters, synaptic cleft, postsynaptic membrane (interaction with receptors), generation of EPSP AP.
1. In chemical synapses, excitation is transmitted using mediators. 2. Chemical synapses have one-way conduction of excitation. 3.Fatigue (depletion of neurotransmitter reserves). 4.Low lability imp/sec. 5. Summation of excitation 6. Blazing a path 7. Synaptic delay (0.2-0.5 m/s). 8. Selective sensitivity to pharmacological and biological substances. 9.Chemical synapses are sensitive to temperature changes. 10. There is trace depolarization at chemical synapses. PHYSIOLOGICAL PROPERTIES OF CHEMICAL SYNAPSES
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.
METHODS OF RESEARCH OF THE CNS 1. Extirpation (removal: partial, complete) 2. Irritation (electrical, chemical) 3. Radioisotope 4. Modeling (physical, mathematical, conceptual) 5. EEG (registration of electrical potentials) 6. Stereotactic technique. 7. Development of conditioned reflexes 8. Computed tomography 9. Pathological method
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.
- 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.
- 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.
- - 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.
- 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-.
- 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
- Returnable;
- Reciprocal (conjugate);
- Lateral.
- 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).
- 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).
- 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.
- Coordination of reflex acts. Directs excitation to certain nerve centers or along a certain path, turning off those neurons and paths whose activity is currently unimportant. 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.
- 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.
- 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 the physiological mechanism of the “common final path” principle.
- 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.
- 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.
Multimedia support for lectures on “Fundamentals of neurophysiology and GND” General physiology of the central nervous system and excitable tissues
Basic manifestations of vital activity Physiological rest Physiological activity Irritation Excitation Inhibition
Types of biological reactions Irritation is a change in structure or function under the influence of an external stimulus. Excitation is a change in the electrical state of the cell membrane, leading to a change in the function of a living cell.
Structure of biomembranes The membrane consists of a double layer of phospholipid molecules, covered on the inside with a layer of protein molecules, and on the outside with a layer of protein molecules and mucopolysaccharides. The cell membrane has very thin channels (pores) with a diameter of several angstroms. Through these channels, molecules of water and other substances, as well as ions with a diameter corresponding to the size of the pores, enter and leave the cell. Various charged groups are fixed on the structural elements of the membrane, which gives the channel walls a particular charge. The membrane is much less permeable to anions than to cations.
Resting potential Between the outer surface of the cell and its protoplasm at rest there is a potential difference of the order of 60-90 mV. The surface of the cell is charged electropositively with respect to protoplasm. This potential difference is called the membrane potential, or resting potential. Its accurate measurement is possible only with the help of intracellular microelectrodes. According to the Hodgkin-Huxley membrane-ion theory, bioelectric potentials are caused by the unequal concentration of K+, Na+, Cl- ions inside and outside the cell, and the different permeability of the surface membrane to them.
Mechanism of MP formation At rest, the membrane of nerve fibers is approximately 25 times more permeable to K ions than to Na + ions, and when excited, sodium permeability is approximately 20 times higher than potassium. Of great importance for the occurrence of membrane potential is the concentration gradient of ions on both sides of the membrane. It has been shown that the cytoplasm of nerve and muscle cells contains 30-59 times more K + ions, but 8-10 times less Na + ions and 50 times less Cl - ions than the extracellular fluid. The value of the resting potential of nerve cells is determined by the ratio of positively charged K + ions, diffusing per unit time from the cell outward along the concentration gradient, and positively charged Na + ions, diffusing along the concentration gradient in the opposite direction.
Distribution of ions on both sides of the cell membrane Na + K +A – Na +K + rest excitation
Na. Na ++ -K-K ++ - - membrane pump 2 Na +3K + ATP -ase
Action potential If a section of a nerve or muscle fiber is exposed to a sufficiently strong stimulus (for example, a jolt of electric current), excitation occurs in that section, one of the most important manifestations of which is a rapid oscillation of the MP, called an action potential (AP)
Action potential In AP, it is customary to distinguish between its peak (the so-called spike) and trace potentials. The PD peak has an ascending and descending phase. Before the ascending phase, a more or less pronounced so-called local potential, or local response. Since the initial polarization of the membrane disappears during the ascending phase, it is called the depolarization phase; accordingly, the descending phase, during which membrane polarization returns to its original level, is called the repolarization phase. The duration of the AP peak in nerve and skeletal muscle fibers varies within 0.4-5.0 ms. In this case, the repolarization phase is always longer.
The main condition for the occurrence of AP and spreading excitation is that the membrane potential must become equal to or less than the critical level of depolarization (Eo<= Eк)
CONDITION OF SODIUM OUTPUT CHANNELS A L A D E P O L A R I S A T I O N S R E P O L A R I S A T I O N
Excitability parameters 1. Excitability threshold 2. Useful time 3. Critical slope 4. Lability
Threshold of stimulation The minimum value of stimulus strength (electric current) required to reduce the membrane charge from the resting level (Eo) to the critical level (Eo) is called the threshold stimulus. Threshold of irritation E p = Eo - Ek Subthreshold stimulus is less powerful than threshold Above-threshold stimulus is stronger than threshold
The threshold strength of any stimulus, within certain limits, is inversely related to its duration. The curve obtained in such experiments is called the “force-duration curve.” From this curve it follows that a current below a certain minimum value or voltage does not cause excitation, no matter how long it lasts. The minimum current strength that can cause excitation is called rheobase. The shortest time during which an irritating stimulus must act is called useful time. Increasing the current leads to a shortening of the minimum stimulation time, but not indefinitely. With very short stimuli, the force-time curve becomes parallel to the coordinate axis. This means that with such short-term irritations, excitation does not occur, no matter how great the strength of irritation.
LAW "STRENGTH IS DURATION"
Determining useful time is practically difficult, since the point of useful time is located on a section of the curve that turns into parallel. Therefore, it is proposed to use the useful time of two rheobases - chronaxy. Chronaximetry has become widespread both experimentally and clinically for diagnosing damage to motor nerve fibers.
LAW "STRENGTH IS DURATION"
The threshold value for irritation of a nerve or muscle depends not only on the duration of the stimulus, but also on the steepness of the increase in its strength. The irritation threshold has the smallest value for rectangular current impulses, characterized by the fastest possible increase in current. When the slope of the current increase decreases below a certain minimum value (the so-called critical slope), the PD does not occur at all, no matter to what final strength the current increases. The phenomenon of adaptation of excitable tissue to a slowly increasing stimulus is called accommodation.
The “all or nothing” law According to this law, under threshold stimuli they do not cause excitation (“nothing”), but with threshold stimuli, excitation immediately acquires a maximum value (“all”), and no longer increases with further intensification of the stimulus.
lability The maximum number of impulses that excitable tissue is capable of reproducing in accordance with the frequency of stimulation nerve - over 100 Hz muscle - about 50 Hz
Laws of excitation conduction Law of physiological continuity; Law of bilateral conduction; Law of isolated conduction.
The location where the axon originates from the nerve cell body (axon hillock) is of greatest importance in the excitation of the neuron. This is the trigger zone of the neuron; it is here that excitation occurs most easily. In this area for 50-100 microns. the axon does not have a myelin sheath, therefore the axon hillock and the initial segment of the axon have the lowest irritation threshold (dendrite - 100 mV, soma - 30 mV, axon hillock - 10 mV). Dendrites also play a role in the excitation of a neuron. They have 15 times more synapses than the soma, so PDs passing along the dendrites to the soma can easily depolarize the soma and cause a volley of impulses along the axon.
Features of neuronal metabolism High consumption of O 2. Complete hypoxia for 5-6 minutes leads to the death of cortical cells. Ability for alternative routes of exchange. The ability to create large reserves of substances. A nerve cell lives only with glia. Ability to regenerate processes (0.5-4 microns/day).
Classification of neurons Afferent, sensitive Associative, intercalary Efferent, effector, motor receptor muscle
Afferent stimulation is carried out along fibers that differ in the degree of myelination and, therefore, in the speed of impulse conduction. Type A fibers are well myelinated and conduct excitations at speeds of up to 130-150 m/s. They provide tactile, kinesthetic, as well as rapid pain sensations. Type B fibers have a thin myelin sheath and a smaller overall diameter, which also leads to a lower impulse conduction speed - 3-14 m/s. They are components of the autonomic nervous system and do not participate in the work of the skin-kinesthetic analyzer, but can conduct some of the temperature and secondary pain stimuli. Type C fibers - without a myelin sheath, impulse conduction speed up to 2-3 m/s. They provide slow pain, temperature and pressure sensations. Usually this is vaguely differentiated information about the properties of the stimulus.
Synapse(s) is a specialized zone of contact between neurons or neurons and other excitable cells, ensuring the transfer of excitation with the preservation, change or disappearance of its information value.
Excitatory synapse – a synapse that excites the postsynaptic membrane; an excitatory postsynaptic potential (EPSP) arises in it and the excitation spreads further. An inhibitory synapse is a synapse on the postsynaptic membrane of which an inhibitory postsynaptic potential (IPSP) arises, and the excitation that comes to the synapse does not spread further.
Classification of synapses Based on location, neuromuscular and neuroneuronal synapses are distinguished, the latter in turn divided into axo-somatic, axo-axonal, axo-dendritic, dendro-somatic. According to the nature of the effect on the perceptive structure, synapses can be excitatory or inhibitory. According to the method of signal transmission, synapses are divided into electrical, chemical, and mixed.
Reflex arc Any reaction of the body in response to irritation of receptors when the external or internal environment changes and carried out through the central nervous system is called a reflex. Thanks to reflex activity, the body is able to quickly respond to environmental changes and adapt to these changes. Each reflex is carried out thanks to the activity of certain structural formations of the NS. The set of formations involved in the implementation of each reflex is called a reflex arc.
Principles of classification of reflexes 1. By origin - unconditional and conditional. Unconditioned reflexes are inherited, they are enshrined in the genetic code, and conditioned reflexes are created in the process of individual life on the basis of unconditioned ones. 2. According to biological significance → nutritional, sexual, defensive, orientation, locomotor, etc. 3. According to the location of the receptors → interoceptive, exteroceptive and proprioceptive. 4. By type of receptors → visual, auditory, gustatory, olfactory, pain, tactile. 5. According to the location of the center → spinal, bulbar, mesencephalic, diencephalic, cortical. 6. According to the duration of the response → phasic and tonic. 7. By the nature of the response → motor, secretory, vasomotor. 8. By belonging to the organ system → respiratory, cardiac, digestive, etc. 9. By the nature of the external manifestation of the reaction → flexion, blinking, vomiting, sucking, etc.
1. For the interconnection of sets of neurons (nerve centers) of one or different levels of the nervous system; 2. To transmit afferent information to the regulators of the nervous system (to the nerve centers); 3. To generate control signals. The name “conducting pathways” does not mean that these pathways serve exclusively to conduct afferent or efferent information, similar to the conduction of electric current in the simplest electrical circuits. Chains of neurons - pathways are essentially hierarchically interacting elements of the system regulator. It is in these hierarchical chains, as elements of regulators, and not just at the end points of paths (for example, in the cerebral cortex), that information is processed and control signals are generated for control objects of body systems. 4. To transmit control signals from nervous system regulators to control objects - organs and organ systems. Thus, the initially purely anatomical concept of “path”, or the collective “path”, “tract” also has a physiological meaning and is closely related to such physiological concepts as a control system, inputs, regulator, outputs.
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 extension)
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
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