Parabiosis stages. N. Teaching
On an isolated bleeding neuromuscular drug frog N. E. The injected combined continuous and intermittent nerve irritation. It was found that under action on the floor of the nerve of drugs or, when he heated or cooling, during squeezing, the action of a strong, etc. This area decreases. When passing through this section of the excitation waves caused by intermittent rhythmic irritation of the nerve, above this area, i.e., on the muscles, there are three main functional states of this plot, or stage. The first stage is preliminary (pharmaceutical), or equalizing. In this stage, weak and strong excitation waves coming from the normal section of the nerve, passing through the changed area, give approximately the same height of Tetanus. These excitation waves reduce lability and lead to the emergence of the second stage - paradoxical. In this stage, the strong irritation of the normal section of the nerve or does not cause Tetanus or causes low Tetanus. Finally, it comes last stage - Brake, when the weak and very strong irritations of the normal section of the nerve do not cause Tetanus. In this stage, complete refractoriness is observed when the modified nerve temporarily lost the ability to function, but it is still alive, since, with the termination of the irritant, its physiological properties are restored. This phenomenon of N. E. Vvedensky called parabital.
In the parabiasis section, an alteration occurs - change, denaturation and change in the structure of nerve fibers. The change in the physiological properties of an allyed plot may result in its dying. N. E. Vvedensky (1901) gave the following scheme of consistent states of an allyed plot: peace - excitation - braking - death. Consequently, parabital is a state, border between life and death.
Parabitosis takes place in two phases: 1) increasing the excitability and increase the maximum and optimal rhythm of the excitation (phase of the electro positive focus of parabiosis, hyperpolarization) and 2) reduction of excitability, lowering the optimal and especially maximum excitation rhythm (phase of electronegability of parabiosis, depolarization). Therefore, in the first phase of parabiasis, there are phenomena characteristic of the subsequent effect of the direct current anode (analchoton), and in the second phase of parabital, the phenomena are typical for the subsequent effect of the direct current cathode (Khaelectron). Depending on the nature of the stimuli, it is more pronounced either the first or the second phase of parabitean. Some authors recognize a parabiotic range - non-light (unlimited) dissemination of changes in excitability (increasing and lowering excitability) due to the occurrence of a parabiotic focus. This is a tonic nervous alarm associated with the existence of a periempotrotone. When enhanced irritation of single nervous fiber, the currents of action are rapidly. Strengthening irritation to a certain critical limit increases Tetanus.
Nervous fibers possess lability- the ability to reproduce a certain number of excitation cycles per unit of time in accordance with the rhythm of existing irritants. The measure of lability is the maximum number of excitation cycles, which can reproduce the nerve fiber per unit of time without transformation of the irritation rhythm. The lability is determined by the duration of the peak of the potential of the action, i.e. the phase of absolute refractoriness. Since the duration of absolute refractoriness in the spike potential of the nerve fiber is the shortest, the lability is the highest. Nervous fiber can reproduce up to 1000 pulses per second.
Phenomenon parabiosis Opened by the Russian physiologist N.E.Vedhensky in 1901 when studying the excitability of the neuromuscular drug. Parabiasis condition can cause various impacts - heavy-blooded, supreme incentives, poisons, medicines and other influences both in the norm and pathology. N. E. Vvedensky found that if the nerve site is subjected to alteration (i.e., the impact of the damaging agent), the lability of such a plot decreases dramatically. Restoring the initial state of the nervous fiber after each action potential in the damaged area is slow. Under action to this section of frequent stimuli, it is not able to reproduce the specified irritation rhythm, and therefore pulses are blocked. Such a state of reduced lability and was named by N. E. Introduced Parabites. The state of parabiasis of the excitable tissue occurs under the influence of strong irritants and is characterized by phase violations of conductivity and excitability. 3 phases are isolated: the primary, the highest activity phase (optimum) and the phase of reduced activity (pessimum). The third phase combines 3 successively by replacing each other stage: equalizing (piercing, transforming - by N.E.Vedhensky), paradoxical and braking.
The first phase (premum) is characterized by a decrease in excitability and increasing lability. In the second phase (optimum), excitability reaches a maximum, lability begins to decline. In the third phase (pessimum), excitability and lability are reduced in parallel and the 3 parabios stages are developing. The first stage is equalized by I.P.Pavlov - is characterized by aligning responses to strong, frequent and moderate irritations. IN equation phasethe adjustment of the response to frequent and rare stimuli is occurring. In normal conditions of functioning of the nervous fiber, the magnitude of the response of the muscular fiber is inexvained to them is subject to the law of force: the response is less for rare stimuli, and the frequent stimuli is more. Under the action of a parabiotic agent and with a rare irritation rhythm (for example, 25 Hz), all excitation impulses are carried out through a parabiotic portion, since the excitability after the previous pulse has time to recover. With a high rhythm of irritation (100Hz), subsequent impulses can act at the moment when the nerve fiber is still in a state of relative refractory caused by the previous potential of action. Therefore, part of the pulses is not carried out. If only every fourth excitation is carried out (ie, 25 pulses out of 100), then the amplitude of the response becomes the same as on rare stimuli (25Hz) -Products the equalization of the response.
The second stage is characterized by a perverted response - strong irritations cause a smaller response than moderate. In this - paradoxical phasethere is a further decrease in lability. At the same time, the response is rare and frequent irritants, but it is much smaller to frequent stimuli, since the frequent stimuli reduce the lability, extending the phase of absolute refractoriness. Therefore, there is a paradox of rare stimuli response more than frequent.
IN brake phasethe lability is reduced to such an extent as rare, and frequent stimuli do not cause a response. At the same time, the membrane of the nerve fiber depolarized and does not go into the stage of repolarization, i.e., its initial state is not restored. Neither strong nor moderate irritations cause a visible reaction, braking develops in the tissue. Parabitating reversible. If a parabiotic substance acts long, then after the cessation of its operation, the nerve comes out of the state of parabiosis through the same phases, but in the reverse order. However, under the action of strong stimuli behind the brake stage, a complete loss of excitability and conductivity may occur, and in the future - the death of the fabric.
Works by N.E.Vedensky in parabitals played an important role in the development of neurophysiology and clinical medicine, showing the unity of the processes of initiation, braking and peace, changed the law of power relations dominant in physiology, according to which the reaction is the greater than the stronger irritant.
Parabiosis phenomenon underlies drug-based local anesthesia. The effect of anesthetic substances knitted with a decrease in lability and a violation of the mechanism for excitation by nerve fibers.
There are a number of laws that are subject to excitable fabrics: 1. The Law "Forces"; 2. The Law "All or Nothing"; 3. The Law "Force - Time"; 4. The law "Current increases"; 5. The Law of the Polar Action of DC.
The law "Forces" The more stroke strength, the greater the quantity of the response. For example, the size of the reduction of the skeletal muscle within certain limits depends on the strength of the stimulus: the greater the power of the stimulus, the greater the reduction of the skeletal muscle (until the maximum response).
The law "All or nothing" response does not depend on the force of irritation (threshold or overspall). If the power of the stimulus is below the threshold, then the fabric does not react ("nothing"), but if the power reached threshold, then the response is the maximum ("all"). Accordingly, this law is reduced, for example, a heart muscle that reacts with a maximum reduction already on the threshold (minimum) irritation force.
The law "Force - Time" The time of the tissue response depends on the force of irritation: the more the power of the irritant, the less time it should act to cause the excitation of the fabric and, on the contrary.
The Act "Accommodation" to cause excitement, the stimulus should increase quickly enough. Under the action of slowly increasing current, the excitation does not occur, since the adaptation of the excitable tissue to the action of an irritant occurs. This phenomenon is called accommodation.
The Act of the "Polar Action" of the DC under the action of direct current, excitation occurs only at the time of closure and opening of the chain. When closed - under the cathode, and when opening - under the anode. The excitation under the cathode is greater than under the anode.
The physiology of the nervous trunk in structure is distinguished by myelin and miserable nerve fibers. In myeline - the excitement extends jumps like. In messenger - continuously along the entire membrane, using local currents.
The laws of initiation on N / B 1. The law of bilateral excitation: the initiation of nerve fiber It may be distributed in two directions from its place of irritation - centripetally and centrifugal. 2. The law of isolated excitation: each nerve fiber, which is part of the nerve, is excited in isolation (PD is not transmitted from one fiber to another). 3. The law of anatomical and physiological integrity of the nervous fiber: for the excitation, anatomical (structural) and physiological (functional) integrity of the nervous fiber is necessary.
The doctrine of parabital developed N. E. Vvedensky in 1891 paradoxical paradoxical phases
Nervous muscular synaps is a structural and functional education that provides excitation transmission from a nervous fiber to muscle. Synaps consists of the following structural elements: 1 - presynaptic membrane (this is part of the nervous end membrane, which is in contact with muscle fiber); 2 - synaptic slit (its width of 20 -30 nm); 3 - postsynaptic membrane (terminal plate); In the nervous end there are numerous synaptic bubbles containing the chemical mediator of excitation transmission from the nerve to the muscle - the mediator. In neuromuscular synapse, the mediator is acetylcholine. In each bubble - about 10,000 acetylcholine molecules.
Stages of neuromuscular transmission The first stage - the release of acetylcholine (ah) into the synaptic gap. It begins with depolarization of the presynaptic membrane. In this case, the SA channels are activated. Calcium on a concentration gradient is included in the nervous end and contributes to the emission by exocytosis of acetylcholine from synaptic bubbles into the synaptic slot. The second stage: the mediator (Ah) by diffusion reaches a postsynaptic membrane, where interacts with the cholinoreceptor (XP). The third stage is the emergence of excitation in muscle fiber. Acetylcholine interacts with a cholinoreceptor on a postsynaptic membrane. In this case, the chemis-duty Na -Chanals are activated. The flow of Na + ions from the synaptic slit inside the muscle fiber (according to the concentration gradient) causes depolarization of the postsynaptic membrane. There is a potential of the terminal plate (PKP). The fourth stage is the removal of the ah of the synaptic gap. This process occurs under the action of enzyme - acetylcholinesterase.
Resintez ah for transmission through synaps one PD requires about 300 bubbles with ah. Therefore, it is necessary to constantly restore the reserves of Ah. Resintez ah occurs: due to decay products (choline and acetic acid); New synthesis of the mediator; The use of the required components by nerve fiber.
Violation of synaptic conductivity Some substances can partially or completely block neuromuscular transmission. Basic blocking paths: a) blockade of excitation of nervous fiber (local anesthetics); b) violation of the synthesis of acetylcholine in the presynaptic nervous end, c) inhibition of acetylcholinesterase (FOS); d) binding of the cholinoreceptor (-bugarotoxin) or long-term displacement ah (coarara); Inactivation of receptors (succinylcholine, decametonium).
Motor units to each muscular fiber fits a motor mechanone. As a rule, 1 motioneon innervates several muscle fibers. This is a motor (or motor) unit. Motor units differ in size: the volume of the body of the motionerone, its axon thickness and the number of muscle fibers included in the motor unit.
Muscle physiology muscle functions and their meaning. Physiological properties of muscles. Muscle cuts. Muscle cutting mechanism. Work, strength and fatigue of muscles.
18 muscle functions in the body exist 3 types M. (skeletal, hearty, smooth), which carry out movement in space interconnecting parts of the body maintaining poses (sitting, standing) heat generation (thermoregulation) blood movement, lymphs inhale and exhale movement of food in the duct internal organs
19 Muscle properties M. possess the following properties: 1. excitability; 2. conductivity; 3. reduction; 4. Elasticity; 5. Extension.
20 Types of muscle cuts: 1. Isotonic - when the length of the muscles changes with the reduction (they are shortened), but the tension (tone) of the muscles remains constant. Isometric cuts are characterized by an increase in muscle tone, while the muscle length does not change. Auxotonic (mixed) - reductions in which the length changes and the muscle tone.
21 Types of muscle contraction: also distinguish single and totanic muscle contractions. Single abbreviations There are in response to the action of rare solitary impulses. With a high frequency of irritating pulses, the sum of muscle contractions occurs, which causes long-lasting muscle shortening - Tetanus.
Toto-totanus occurs in conditions when each subsequent pulse falls during the relaxation of a single muscular abbreviation
Smooth Tetanus arises in conditions when each subsequent pulse falls during the shortening period of a single muscular reduction.
31 Muscular cutting mechanism (sliding theory): excitation transition from nerve to muscle (through neuro-muscular synaps). The propagation of the PD along the muscular fiber membrane (sarclamem) and in the depth of the muscle fiber in the t-tube (transverse tubes - the deepening of the sarcollama in the sarcoplasma) release of Ca ++ ions from lateral tanks of sarcoplasmic reticulum (calcium depot) and its diffusion to myofibrils. The interaction of CA ++ with protein - troponin, located on actin threads. Release centers for actines and contact of the transverse bridges of myozin with these areas of actin. The release of ATP energy and gliding actin yarn along the alone threads. This leads to the shortening of myofibrils. Next, the calcium pump is activated, which provides active transportation of Ca from sarcoplasm to sarcoplasmic reticulm. The concentration of sa in sarcoplasm decreases, as a result, miofibrilla relaxation occurs.
Muscle power is the maximum cargo that muscles raised, or the maximum voltage that it develops with its reduction is called the power of the muscles. It is measured in kilograms. Muscle strength depends on the thickness of the muscle and its physiological cross section (this is the sum of the transverse sections of all muscle fibers that make up this muscle). In muscles with longitudinal muscle fibers, the physiological cross-section coincides with the geometric. The muscles with the oblique location of the fibers (muscles of a peristry type) physiological cross-section greatly exceeds the geometric section. They belong to the power muscles.
Types of muscle A - parallel b - periody in - spindle-shaped
The work of the muscle lifting the cargo, the muscle performs mechanical work, which is measured by the product of the cargo to the height of its lifting and is expressed in kilogram meters. A \u003d f x s, where f - the weight of the load, S is the height of its lift if f \u003d 0, then the operation is a \u003d 0 if S \u003d 0, then work A \u003d 0 The maximum work of the muscle is performed at average loads (the law "Middle loads).
Tlying is called a temporary decline in muscle performance as a result of long, excessive loads that disappears after rest. Target is a complex physiological process associated primarily with the fatigue of nervous centers. According to the theory of "clogging" (E. Plfulger), a certain role in the development of fatigue plays the accumulation in the working muscle of the commercial products (lactic acid, etc.). According to the theory of "exhaustion" (K. Schiff), fatigue is caused by gradual exhaustion in the working muscles of energy reserves (ATP, Glycogen). Both of these theories are formulated on the basis of data obtained in experiments on an isolated skeletal muscle and explain fatigue one-way and simplistic.
The theory of active recreation to the present time a single theory explaining the cause and essence of fatigue is not. In natural conditions, the fatigue of the organismist organism is a multifactor process. I. M. Sechenov (1903), examining on the ergograph designed by him for two hands, the performance of the muscles when lifting the cargo, found that the operability of a tired right hand is restored fully and faster after active recreation, that is, recreation accompanied by the work of the left hand. Thus, the active rest is more effective tool Combating muscle fatigue than simple peace. The reason for the restoration of muscle performance under conditions of active recreation of Sechenov connected with the action on the CNS of afferent impulses from muscle, tendon receptors of working muscles.
Parabiosis - Means "Near Life". It occurs when actions on the nerves parabiotic stimuli (ammonia, acid, fat solvent, KCL, etc.), this stimulus changes lability , reduces it. And reduces its phase, gradually.
^ Parabiosis phases:
1. First observed equalizing phase Parabecia. Usually a strong stimulus gives a strong answer, and the smaller is smaller. Here there are equally weak answers to various stimuli (demonstration of the schedule).
2. The second phase - paradoxical phase Parabecia. A strong stimulus gives a weak answer, a weak - strong answer.
3. Third Phase - brake phase Parabecia. And there is no answer to the weak and strong irritant. This is due to the change in lability.
The first and second phase - reversible . With the termination of the parabiotic agent, the fabric is restored to a normal state, to the initial level.
The third phase is not reversible, the brake phase passes through a short period of time into the death of the fabric.
^ The mechanisms of parabiotic phases
1. The development of parabiasis is due to the fact that under the action of the damaging factor occurs reduction of lability, functional mobility . This is the basis of answers that call parabiosis phases .
2. In normal condition, the fabric obeys the law of irritation force. The greater the power of irritation, the greater the answer. There is an irritant that causes the maximum answer. And this value is indicated as the optimum frequency and force of irritation.
If this frequency or the power of the stimulus exceeds, the response is reduced. This phenomenon is pessimum frequency or irritation force.
3. The value of the optimum coincides with the magnitude of lability. Because Labeliness is the maximum ability of the fabric, the maximum possible tissue response. If the lability changes, then the values \u200b\u200bin which instead of optimum develops pessimum, shifted. If you change the lability of the tissue, then the frequency that caused the optimum response will now cause pessimum.
Biological Parabiosis
The discovery of the injected parabiosis on a neuromuscular drug in the laboratory had colossal consequences for medicine:
1. showed that death phenomenon not instantly , There is a transition period between life and death.
2. This transition is carried out phazno .
3. The first and second phases reversible , and the third not reversible .
These discoveries led in medicine to the concepts - clinical death, biological death.
Clinical death - This is a reversible condition.
^ Biological death - irreversible condition.
As soon as the concept of "clinical death" was formed, a new science appeared - resuscitation ("Re" - a return pretext, "Anima" - life).
^ 9. DC effect ...
Permanent current on the fabric has Two types of action:
1. Exciting action
2. Electrotonic action.
The excitation effect is formulated in three porugger laws:
1. Under the action of a direct current on the fabric, the excitation occurs only at the time of circuit of the chain or at the time of opening the chain, or with a sharp change in the current force.
2. Excitation occurs when closed under the cathode, and when opening - under the anode.
3. The cathodezacing threshold is less than the threshold of annexicing effect.
We will analyze these laws:
1. The excitation occurs during closure and opening or with a strong current of the current, because it is these processes that create the necessary conditions for the occurrence of depolarization of membranes under the electrodes.
2. ^ Under the cathode, closure chain, we substantially enter the powerful negative charge on the outer surface of the membrane. This leads to the development of the depolarization process of the membrane under the cathode.
Therefore, it is precisely under the cathode that the process of excitation during closure occurs.
Consider a cage under the anode. When the circuit is closed, there is a powerful positive charge on the surface of the membrane, which leads to membrane hyperpolarization. Therefore, under the anode there is no excitement. Under the action of current develops accommodation. Kud. shifted Following the potential of the membrane, but to a lesser extent. Ecavitability is reduced. No conditions for excitement
We open the chain - the potential of the membrane will quickly return to the initial level.
^ Kudok quickly cannot change, it will return gradually and rapidly changing the potential of the membrane will reach Kud -there will be an arousal . In thatmain reason thatexcitation arisesat the moment of opening.
At the moment of opening under the cathode ^ Kud slowly returns to the initial level, and the membrane potential does it quickly.
1. under the cathode at durable action DC to the fabric will appear phenomenon - catail depression.
2. Under the anode at the time of the closure there will be an anode block.
The main feature of the catalog depression and the anode block is Reducing excitability and conductivity to zero level.However, the biological tissue remains alive.
^ Electrootonic action of direct current on fabric.
Under an electrotonic action, the action of direct current on the fabric is understood, which leads to a change in the physical and physiological properties of the tissue. In connection with these distinguishes two types of electrotroid:
Physical electrotone.
Physiological electrotone.
Under the physical electrotone understand the change physical properties Membranes occurring under the action of DC - change permeability Membranes, critical level of depolarization.
Under physiological electrotone, the change in the physiological properties of the tissue is understood. Namely - empathy, conductivity Under the action of electric flow.
In addition, the electrotone is divided into the analchoton and the canoecotrotone.
Annechoton - changes in the physical and physiological properties of tissues under the action of the anode.
Caekelectron - changes in the physical and physiological properties of tissues under the action of the cathode.
The permeability of the membrane will change and this will be expressed in the hyperpolarization of the membrane and under the action of the anode will be gradually decreased by KUD.
In addition, under the anode under the action of constant electric current develops physiological component of electrotroid. So under the action of the anode varies excitability. How does the excitability change under the action of the anode? Included electric strokes - Kud shifts down, the membrane hyperpolarized, the level of rest potential was dramatically shifted.
The difference Majda Kudud and the rest potential increases at the beginning of the electrical current under the anode. So excitability under the anode at the beginning will decrease. The membrane potential will slowly shift down, and Kud is strong enough. This will lead to the recovery of excitability to the initial level, and with a long-term action of the DC under the anode, excitability will grow upsince the difference between the new level where the membrane potential is less than alone.
^ 10. Building Biommbran ...
The organization of all membranes has a lot in common, they are built in the same principle. The basis of the membrane is a lipid bilayer (double layer of amphiphilic lipids) that have a hydrophilic "head" and two hydrophobic "tail". In the lipid layer, lipid molecules are spatially oriented, addressed to each other with hydrophobic "tails", the heads of molecules are facing the outer and inner surface of the membrane.
^ Membrane lipids: phospholipids, sphingolipids, glycolipids, cholesterol.
Perform, in addition to the formation of the bilipid layer, other functions:
form an environment for membrane proteins (altowork activators of a number of membrane enzymes);
are predecessors of some second intermediaries;
Perform an "anchor" function for some peripheral proteins.
Among membranes belkov Allocate:
peripheral - located on the outer or inner surfaces of the bilipid layer; On the outer surface, they include receptor proteins, adhesion proteins; On the inner surface - system proteins secondary intermediaries, enzymes;
integral - Partially immersed in the lipid layer. These include receptor proteins, adhesion proteins;
transmembrane - permeate the whole membrane turn, and some proteins pass through the membrane once, and others - repeatedly. This type of membrane proteins generates pores, ion channels and pumps, carrier proteins, receptor proteins. Transmembrane proteins play a leading role in the interaction of the environment with the environment, providing a signal reception, carrying it into a cell, gain at all distribution stages.
In the membrane, this type of protein forms domains (Subunits), which provide transmembrane proteins of essential functions by transmembrane proteins.
The domain base is the transmembrane segments formed by non-polar amino acid residues shrewd in the form of OS-helix and emembrane loops representing the polar areas of proteins, which can be quite far beyond the bilipid layer of the membrane (denoted as intracellular, extracellular segments), separately seen and NN 2 -Terminal domains.
Often simply allocate transmembrane, out and intracellular parts of the domain - subunit. Membrane proteins also divide on:
Structural proteins: Press the membrane form, a number of mechanical properties (elasticity, etc.);
Transport proteins:
Form transport streams (ion channels and pumps, carriers proteins);
Protect the creation of transmembrane potential.
Proteins providing intercellular interactions:
Adhesive proteins, bind cells with each other or with extracellular structures;
protein structures involved in the formation of specialized intercellular contacts (desplaomomomy, nexus, etc.);
Proteins directly participating in the transmission of signals from one cell to another.
The membrane includes carbohydrates in the form of glycolipid and glycoprotein. They form oligosaccharide chains, which are located on the outer surface of the membrane.
^ Membrane properties:
1. Self-assembly in aqueous solution.
2. Circuit (self-seating, closedness). The lipid layer always closes itself to the formation of fully delimited compartments. This provides self-access during the membrane damage.
3. Asymmetry (transverse) - the outer and inner layers of the membrane differ in composition.
4. Liquidity (mobility) of the membrane. Lipids and proteins can be moved in their layer under certain conditions:
lateral mobility;
rotation;
bending,
And also go to another layer:
Vertical movements (flip flops)
5. Semipermeability (selective permeability, selectivity) for specific substances.
^ Membrane functions
Each of the membranes in the cell plays its biological role.
Cytoplasmic membrane:
Rewards the cell from the environment;
Carries out the regulation of metabolism between the cell and the microenvironment (transmembrane exchange);
Recognition and reception of irritants;
Takes part in the formation of intercellular contacts;
Ensures the attachment of cells to the extracellular matrix;
Generates electrosenesis.
Date added: 2015-02-02 | Views: 3624 |
Many physiological states of humans and animals, such as the development of sleep, hypnotic states can be explained from parabiosis positions. In addition, the functional value of parabiasis is determined by the mechanism of action of some medicines. So, at the heart of the dual, local anasthetics (Novocaine, Lidocaine, etc.), analgesics, inhalation of the anesthesia lies this phenomenon.
Local anesthetics (from Greek. An - denial, Aesthesis - sensitivity) reversibly reduce the excitability of sensitive nerve endings and block the conduction of the pulse in the nerve conductors at the place of direct use. These substances are used to eliminate pain. For the first time, the drug from this group of Cocaine was highlighted in 1860 by Albert Niman from the leaves of the South American Shrub Erythroxylon Coca. In 1879 V.K. AREPEMSTOR Military Medical Academy of St. Petersburg confirmed the ability of cocaine to cause anesthesia. In 1905, E. Eindhorn synthesized and applied Novocain for local anesthesia. Since 1948, Lidocaine is used.
Local anesthetics consist of hydrophilic and lipophilic parts, which are connected by ether or alkyd bonds. Biologically (physiologically) the active part is the lipophilic structure, forming an aromatic ring.
The mechanism of the action of local anesthetics is a violation of the permeability of the rapid potential-dependent sodium channels. These substances are associated with open sodium channels during the action potential and cause them to inactivation. Local anesthetics do not interact with closed channels during rest potential and channels in an inactivated state, during the development of the phase of repolarization of the potential of action.
Receptors for local anesthetics are located in S 6 segment of the IV domain of the intracellular part of sodium channels. In this case, the action of local anesthetics reduce the permeability of activated sodium channels. This in turn causes an increase in the arousal threshold, and ultimately, to a decrease in tissue excitability. At the same time, there is a decrease in the number of potentials of action and the rate of excitation. As a result, a block for nerve impulses is formed in the field of application of local anesthetics.
According to one of the theories, the mechanism of action for inhalation of drugs is also described from the standpoint of the theory of parabiosis. NOT. The introduction believed that the means for inhalation of anesthesia act on the nervous system as severe irritants, causing parabiteances. At the same time, there is a change in the physicochemical properties of the membrane and the change in the activity of ion channels. All these processes cause the development of parabios with a decrease in lability, conductivity of neurons and central nervous system generally.
Currently, the term parabital is used in particular to describe pathological and extreme states.
An example of a pathological state are experimental neurosis. They develop as a result of overvoltage in the cerebral cortex of basic nerve processes - excitation and braking, their strength and mobility. Neuroses with a repeated overvoltage of higher nervous activity can occur not only acutely, but also chronically for many months or years.
The neurosis is characterized by a violation of the main properties of the nervous system, normalizing the processes of irritation and excitation determining the relationship. As a result, weakening of the health of nerve cells can be observed, violation of equilibrium, etc. In addition, phase states are characterized for neuroses. Their entity lies in the disorder between the action of the irritant and the response.
Phase phenomena may occur not only in pathological conditions, but also very briefly, for several minutes, when moving from wakefulness to sleep. In neurosis, the following phases are distinguished:
Equability
In this phase, all conditional stimuli, regardless of their strength, give the same answer.
Paradoxical
In this case, weak stimuli give a strong effect, and the strong - the smallest effect.
Ultraparadsal
Phase, when positive stimuli begins to act as negative, and vice versa, i.e. The reaction of the cortex of the brain on the action of irritants occurs.
Brake
It is characterized by the weakening or complete disappearance of all conditional reflector reactions.
However, it is not always possible to observe a strict sequence in the development of phase phenomena. Phase phenomena with neurosis coincide with phases, previously open N.E. Introduced on the nervous fiber when switching it to a parabiotic state.