Neurohumoral regulation of heart work. Nervously - humoral regulation of vascular tone humoral regulation of vascular tone

16.08.2020 Preparations

Nervous regulation. The main center of cardiac regulation is in oblong brain. The excitation of sympathetic nerves increases the power of heart abbreviations (positive inotropic effect), the frequency (positive chronotropic effect), the excitability (positive battle action) and the conductivity (positive drromotropic effect) of the heart muscle. Trophic or amplifying nerve I.P. Pavlova (a branch of a sympathetic nerve) is only a positive inotropic effect. The wandering nerve (parasympathetic) has negative ina, chrono-, butmol and drromotropic effect on the heart. The heart is under the tone of the wandering nerve (constant braking effect on the heart).

Hemodynamic regulation mechanisms: heterometric regulation (Frank Starling Law) - the stronger the muscle fibers are stretched during the diastole, the more blood flow to the heart, the greater the power of heart abbreviations. Homeometric regulation (does not depend on the initial length of muscle fibers) - the "staircase" of Bouldich (an increase in the frequency of heart cuts at a constant force of the stimulus leads to an increase in the force of heart cuts), the phenomenon of Anurga (the higher the pressure in the aorta and pulmonary arteryThe greater the power of heart abbreviations).

Reflexary regulation of the heart: intracardiac peripheral reflexes (due to intraganic functioning nervous system: All links of reflex arc are in the heart), extracardial mechanisms: reflexes from the heart on the heart (bainbridge zone), reflexes from the vessels on the heart (synolokarotid zone and the arc area of \u200b\u200bthe aorta), reflexes with organs on the heart (Reflex Golts and Danigni Ashner).

Humoral regulation of the heart of the heart: adrenaline, norepinephrine and dopamine have positive other, chrono-, butmol and drromotropic effect on the heart; Acetylcholine - negative in-chrono-, batmo- and drromotropic influence; Tyroxin is a positive chronotropic effect; glucagon - positive other and chronotropic action; Corticosteroids and angiotensin is a positive inotropic effect. Calcium ions have positive batmo- and inotropic influences, overdose causes a heart stop in systole; Potassium ions (large doses) - negative batmo- and drromotropic effects and a heart stop in diastole.

Heart research methods: Inspection, palpation, percussion, auscultation, determination of systolic and minute blood volumes, electrocardiography, vector vintage, phonocardiography, ballergardiography, echocardiography, etc.

Vascular system. The flow of blood according to the vessels is subject to the laws of hemodynamics, which is a section of hydrodynamics. Functional classification of vessels: shock absorbing vessels (elastic type vessels); resistive vessels (resistance vessels); sphincter vessels; exchange vessels; capacitive vessels; Shunt vessels (arterio-venous anastomoses). Parameters of blood circulation: blood pressure; linear blood flow rate; The volumetric speed of blood flow; The time of blood circuit. The factors determining the amount of magnitude arterial pressure (HELL): The work of the heart, resistance and elasticity of the vascular wall, the mass of circulating blood, blood viscosity, neurohumoral influences. There are systolic, diastolic, pulse and arid blood pressure. Linear speed of blood flow- The distance that the blood particle passes through the vessels of a certain caliber per unit of time. Blood flow rate - The amount of blood flowing through the vessels of a certain caliber per unit of time. The speed of blood circuit - The time for which the blood particle passes a large and small circles of blood circulation. Arterial Pulse - Rhythmic oscillations of the artery wall due to the increase in pressure during systole. Vienna Pulse - pulse fluctuations in the wall of large veins, due to the difficulty of the blood flow from the veins in the heart during the systole systole and ventricles.

Microcirculation - Processes of blood flow through the smallest blood and lymphatic vessels. Microcirculation includes processes associated with intraigan blood circulation, providing tissue metabolism, redistribution and depositing of blood. In the microcirculation system, 2 types of blood flow distinguish: Slow transcapillary and fast YUCSTAKAPILLER.

Neuro humoral regulation Tonus vessels . Nervous regulation. The main vascular center is in the oblong brain. Sympathetic nerves narrow the vessels; Some parasympathetic nerves (Language, pagan, topless, pelvic) are expanding the vessels of the organ innervocated by them. The vessels are under constant tone of sympathetic nerves. Basal tone - due to the very vascular wall. Additional factors extending vessels: irritation of the rear roots spinal cord, axon reflex, irritation of sympathetic cholinergic fibers. Reflex regulation: own reflexes - reflexes from vessels on vessels (synoloatid and aortic zones) and conjugate reflexes - from organs on the vessels. Gumoral regulation: vasoconductive substances - adrenaline, norepinerenaline, vasopressin, serotonin, renin, endothelin, calcium ions; Vasodilators - Acetylcholine, Histamine, Bradykin, Prostaglandins, Dairy and Pyerogradic Acid, Adenosine, carbon dioxide, nitrogen oxide, potassium and sodium ions.

Vascular research methods: Sphigmography, phlebography, plethysmography, robust.

The lymphatic system is drainage systemThrough which the tissue fluid flows into the bloodstream (venous system). Lymphatic capillaries are closed. Lymphangion is a plot of lymphosor between two valves. Lymph nodes - filters, delaying microorganisms, tumor cells, foreign particles; contain T- and B-lymphocytes responsible for immunity; They produce plasma cells producing antibodies. Functions of the lymphatic system: refund of proteins, electrolytes and water from an interstice in blood system; resorbative, barrier, immunobiological, participation in fat exchange and the exchange of fat-soluble vitamins. The composition of lymph: proteins (albumin, globulines, fibrinogen), lipids, enzymes (lipase and diastasis); chlorine and bicarbonates; Many lymphocytes, little granulocytes and monocytes.

Lesson 1. Heart cycle. Excitation B.

a heart. Automatic. Conductive heart system.

Task 1. Heart cycle at the frog (PR. 87-89).

Task 2.Analysis of the conductive system of heart overlay

ligatures (Stanius ligatures) (Ave. p. 90-92).

Lesson 2. Properties of the heart muscle. Change of excitability

cardiac muscle in various phases of cardiac

activities. Extrasyistol.

Task 1. Playing extrasystole (Ave. p. 98).

Lesson 3. Nervous and humoral regulation of the heart.

Task 1. Influence of irritation of a vague-sympathetic trunk on

heart activity frog. (Ave. p. 111-113).

Lesson 4. Heart research methods. Electric phenomena B.

a heart. Electrocardiography.

Task 1. Registration of electrocardiogram. (Ave. p. 105).

Task 2.Determination of physical performance (test RWS 170)

(PR. 436)

Lesson 5. Physiology of vessels. The main laws of hemodynamics.

Task 1. Blood pressure measurement in humans (by method

Riva-Rachi-Korotkov) (Ave. p. 127).

Task 2. Observation of blood flow in a swimming polar

frogs (Ave. p. 136).

Lesson 6. Methods for researching blood flow. Coronary

bloodstock.

Physiology d s ha i

Breath - Complex, cyclically flowing physiological process, which provides gas exchange (O 2 and CO 2) between the environment and the body in accordance with its metabolic needs. The process of breathing can be divided into several stages: external breathing (gas exchange between atmospheric and alveolar air - "pulmonary ventilation"; gas exchange between the blood of pulmonary capillaries and alveolar air); vehicles of gases blood; exchange of gases between blood and cells of the body; Interior, or tissue breathing.

External respiratory system Includes light and small circulation circle (provide blood arterialization), chest with respiratory muscles (provide respiratory act) and respiratory regulation system (respiratory center and other CNS departments). Inhale: Impulse from the respiratory center - reducing the inspiratory respiratory muscles (diaphragms and external intercostal muscles with a calm breath) - Willing volume chest - increasing negative pressure in the pleural cavity - an increase in the volume of the lungs - a decrease in intra-germinal pressure below atmospheric - air flow into the lungs. Negative pressure in the pleural cavity due to elastic lungs. Elastic lung thrust-Sile, with which the lungs constantly seek to reduce their volume.

Pneumothorax - air intake in pleural cavity. Atelectaz- Amend Alveol.

Pulmonary volumes and capacities: the life capacity of the lungs (jerking), which includes the respiratory volume (up to), the backup volume of the inhalation (ROVD) and the reserve exhalation (RODD); residual volume (oo); Functional residual capacity (Foy \u003d Rowd + oo); total lung tank + oo); The volume of the dead space (air located in the aerial paths and not participating in gas exchange), which is part of before. Pulmonary ventilation. Lone respiratory volume (mod \u003d up to X CH). Alveolar ventilation \u003d (up to-volume dead space) X CH. Gas exchange indicators: oxygen consumption (Vo 2), oxygen use coefficient (KIO 2).

Transport gas blood. The mechanism for transferring oxygen from alveolar air into blood and carbon dioxide from the blood to the alveolar air is diffusion. Oxygen transfer form: oxygen dissolved in plasma; In the form of oxygemoglobin. Oxygen blood capacity- The maximum amount of oxygen, which is capable of tie hemoglobin during its full oxygen saturation. The dissociation curve of oxymemoglobin is the dependence of the binding of oxygen with blood from its partial pressure. Factors affecting its shifts to the right and left (RSO2, temperature, pH). Carbon dioxide transfer form: Carbon dioxide dissolved in plasma; in the form of carbomoglobin; in the form of sodium bicarbonates (in plasma) and potassium (in red blood cell).

Neurohumoral respiratory regulation. Nervous regulation. Centers: spinal (C3-C5 and T2-T10); Bulbarbar (main), consisting of inspiratory and expiratory departments with automation; Varoliev Bridge (pneumotactic). The diaphragmal nerve and intercostal nerves innervat the respiratory muscles. The replete regulation - respiratory reflexes begin with various receptors: slowly adaptable pulmonary stretch receptors (Reflex Goring Breyer, wandering nerve), irritant quickly adapting mechanoreceptors (cough, bronchospasm), J receptors, or " Yuchstakapillary "lung receptors (pulmonary swelling), breathing muscles, peripheral (arterial in carotid sinus) and central (in hypothalamus) chemoreceptors. Humoral regulation: hypercup (increasing CO2 in the blood), hypoxia (lack of oxygen in tissues) and hydrogen ions (acidosis) stimulate breathing. Hitch (reduction of CO2 in blood) and hyperoxia (an increase in O2 in alveolar air) inhibit breathing. Frederic experience with cross circulation. Experience in Holdane.

Methods for the study of the respiratory function: spirometry and spirography, pneumotachography.

Lesson 1. External breathing. Pulmonary volumes and tanks.

Task 1. Spirometry: dry and water spirometers (Ave. p. 174).

Task 2.Definition of a minute volume of breathing alone and

exercise (Ave. p. 188).

Lesson 2. Gas exchange in the lungs. Gas transport blood.

Task 1. Gasanalysis of atmospheric, exhaled, alveolar air

with gas analyzers. (Demonstration).

Task 2. Determination of pH, PO 2, RSO 2 in arterialized blood with

using a microanalyzer. (Demonstration).

Lesson 3. Respiratory regulation.

Task 1.Pnemography (Ave. p. 182).

Task 2. Evaluation of tracheobronchial wood

the "pneumoscreen-2" device. (Demonstration).

Similar information.

Algorithm for the treatment of internal hospitality

Anatomy and histology of the heart. Circle circles. Physiological properties of the heart muscle. Phase analysis of a single cardiac cycle

This regulation is provided complex mechanism, Including sensitive (afferent), central and efferent links.

5.2.1. Sensitive link.Vascular receptors - angioceptor- in its function are divided into baroreceptors(press receptors) reacting to the change in blood pressure, and chemoreceptors, change sensitive chemical composition blood. Their greatest clusters are in main reflexogenic zones:aortic, sylocarotide, in the vessels of the pulmonary circle of blood circulation.

Stimulus baroreceptors It is not pressure as such, but the speed and degree of stretching the wall of the vessel with pulse or increasing blood pressure fluctuations.

Chemoreceptors React to change in blood concentration O 2, CO 2, H +, some inorganic and organic substances.

Reflexes arising from prescription zones of cardio-vascular system and determining the regulation of relationships within exactly this system are called own (system) circulatory reflexes.With an increase in irritation force in the response, in addition to the cardiovascular system, it is involved breath. It will be already conjugated reflex.The existence of conjugated reflexes allows the blood circulation system to quickly and adequately adapt to the changing conditions of the inner environment of the body.

5.2.2. Central linkcall called vasodent (vasomotor) center.The structures relating to the vasomotor center are localized in the spinal, oblong brain, hypothalamus, the crust of large hemispheres.

Spinal level of regulation.Nervous cells whose axons form vesseloring fibers are located in the lateral horns of the chest and first lumbar segments of the spinal cord and are the cores of the sympathetic and parasympathetic system.

Bulbar level regulation.The alternating brain vessels is the main center for maintaining the tone of vessels and reflex regulation of blood pressure.

The vessels center is divided into depressor, pressor and cardioengging zones. This division is quite conditionally, since due to the mutual overlap of zones, it is impossible to determine the boundaries.

Depressor zoneit helps to reduce blood pressure by reducing the activity of sympathetic vesseloring fibers, thereby causing the extension of the vessels and the drop in peripheral resistance, as well as the weakening of the sympathetic stimulation of the heart, i.e. decrease heart Emission.

Pressorny zoneit has the opposite effect, increasing blood pressure through an increase in the peripheral resistance of the vessels and cardiac output. The interaction of decerserous and pressing structures of the vasomotor center is complex synergo-antagonistic.

Cardioengisticthe effect of the third zone is mediated by the fibers of the wandering nerve, reaching the heart. Its activity leads to a decrease in cardiac output and thus combines with the activity of the depressor zone in reducing blood pressure.

The state of the tonic excitation of the vesselor center and, accordingly, the level of total blood pressure is governed by pulses, which are from vascular reflexogenic zones. In addition, this center is part of the reticular formation of the oblong brain, from where numerous collateral excitations also receive from all specifically conductive paths.

Hypotalamic level of regulationit plays an important role in the implementation of adaptive blood circulation reactions. Integrative centers of hypothalamus have a descending effect on the cordial-vascular center of the oblong brain, providing its control. In the hypothalamus, as well as in the boulevard vessels, distinguish depressantand pressorzones.

Corrk level of regulation N.ay mostly studied with conditional reflexes.So, it is relatively easy to work out a vascular reaction to a previously indifferent stimulus, while causing a feeling of heat, cold, pain, etc.

Certain zones of the brain cortex, like the hypothalamus, have a descending effect on the main center of the oblong brain. These influences are formed as a result of a comparison of information, which entered the highest departments of the nervous system from various recipe areas, with the preceding body's experience. They provide the realization of the cardiovascular component of emotions, motivations, behavioral reactions.

5.2.3. Efferent link. Efferent regulation of blood circulation is realized through the smooth muscle elements of the wall of the blood vessel, which are constantly in a state of moderate voltage - vascular tone. There are three mechanism for regulating a vascular tone:

1. AUTORGULATION

2. Nervous regulation

3. Humoral regulation

AuToregulation Provides a change in the tone of smooth muscle cells under the influence of local excitation. Moogenic regulation is associated with a change in the state of smooth muscle cells of the vessels, depending on the degree of their stretching - the effect of witness-beylis. The smooth muscle cells of the walls of the vessels are resolved on stretching and relaxation - to reduce pressure in vessels. Meaning: Maintaining at a constant level of blood volume coming to the organ (the most pronounced mechanism in the kidneys, liver, lung, brain).

Nervous regulation The vascular tone is carried out by the vegetative nervous system, which has a vasoconstrictor and vasodilating effect.

Sympathetic nerves are vasoconstrictors (narrow vessels) for vessels of the skin, mucous membranes, gastrointestinal tract and vasodilators (Expand the vessels) for vessels of the brain, lungs, hearts and working muscles. Parasympathetic The nervous system department has an extensive effect on the vessels.

Innervations are subject to almost all vessels, with the exception of capillaries. The innervation of veins corresponds to the innervation of arteries, although in general the density of the innervation of veins is significantly less.

Humoral regulation It is carried out by substances of system and local action. The systemic substances include calcium, potassium, sodium ions, hormones:

Calcium ions cause narrowing vessels potassium ions Expanding action.

The ability to expand the vessels possess biologically active substances and local hormones, such as histamine, serotonin, bradykin, prostaglandins.

Vasopressin - increases the tone of smooth muscle cells arteriole, causing the narrowing of the vessels;

Adrenalin on artery and arterioles of the skin, digestive, kidney and lung organs vasoconstrictor influence; on the vessels of skeletal muscles, smooth "muscles of bronchi - expandingSupporting the redistribution of blood in the body. In physical tension, emotional excitement, it helps to increase blood flow through skeletal muscles, brain, heart. The effect of adrenaline and norepinephrine on the vascular wall is determined by the existence different types Adrenoreceptors - α and β, representing areas of smooth muscle cells with special chemical sensitivity. Both types of receptors are usually available in vessels. The interaction of mediators with an α-adrenoreceptor leads to a reduction in the vessel wall, with a β-receptor - to relaxation.

Atrial sodium systemic peptide - ma scent vasodilator (expands blood vessels, reducing blood pressure). Reduces reabsorption (reverse absorption) sodium and water in the kidneys (reduces the volume of water in vascular bed). Endocrine atrial cells are released when they are excessive tension.

Tyroxin - stimulates energy processes and causes narrowing blood vessels;

Aldosterone It is produced in the cortical layer of adrenal glands. Aldosterone has an unusually high ability to strengthen the reverse suction of sodium in the kidneys, salivary glands, digestive systemBy changing the sensitivity of the vessel walls to the influence of adrenaline and norepinephrine.

Vasopressin causes the narrowing of the arteries and arterioles of the organs abdominal cavity and lungs. However, as under the influence of adrenaline, the brain and heart vessels react to this hormone expansion, which helps to improve nutrition and brain tissue, and heart muscle.

Angiotenzine II. - this is a product of enzymatic splitting angiotensinogen or angiotensin I.under influence renin.. It has a powerful vasoconstrictor (vesseloring) effect, significantly superior to the power of norepinephrine, but unlike the latter does not cause blood release from the depot. Renin and angiotensin are renin angiotensin system.

In the nervous and endocrine regulation, hemodynamic mechanisms of short-term action are distinguished, intermediate and long action. To mechanisms short-termactions include circulatory reactions of nervous origin - baroreptor, chemoreceptor, reflex on Izhemia CNS. Their development occurs within a few seconds. Intermediate(in time) Mechanisms encompass changes in transcapillary metabolism, relaxation of the stressed vessel wall, reaction of the renin-angiotensin system. For the inclusion of these mechanisms, moments are required, and for maximum development - hours. Regulatory mechanisms longactions affect the ratio between intravascular blood volume ivessel capacity. This is carried out by means of a transcapillary fluid exchange. In this process, the renal regulation of fluid volume, vasopressin and aldosterone is involved.

Date added: 2014-05-22 | Views: 899 | Violation of copyright

| | | | | | 7 | | | | |

In this part, we are talking about the nervous and humoral regulation of the tone of vessels: about the efferent innervation of blood vessels, brief description Vasomotor centers, about the reflex regulation of the tone of the vessels, about humoral regulation of the tone of the vessels.

Nervous and humoral regulation of vessel tone.

The blood supply of organs depends on the size of the vessels from their tone and the number of blood-emitted blood in them. Therefore, when considering the regulation of the function of the vessels, first of all, it is necessary to talk about the mechanisms for maintaining a vascular tone and the interaction of the heart and blood vessels.

Efferent innervation of vessels.

Vascular clearance is mainly regulated by the sympathetic nervous system. Its nerves independently or as part of mixed motor nerves approach all arteries and arteriols and have a vasoconstrictor influence. Bright demonstration of this effect are the experiments of the Bernard Claude, spent on the rabbit's ear vessels. In these experiments, a sympathetic nerve was cut on the neck of the rabbit, after which the redness of the operated side of the operated side was observed and a slight increase in its temperature due to the extension of the vessels and an increase in the blood supply of the ear. The irritation of the peripheral end of the converted sympathetic nerve caused the judgment of the vessels and the broadband of the ear.

Sympathetic nerves, innervating most of the vessels of the abdominal cavity, are suitable for them in the composition of the crank nerve. To the limb vessels, sympathetic fibers come together with motor nerves.

Under the influence of the sympathetic nervous system of the muscles of vessels is in a state of reduction - tonic voltage.

In natural conditions of the body's livelihoods, the change in the lumen of most vessels (their judgment and expansion) occurs due to changes in the number of pulses going on sympathetic nerves. The frequency of these pulses is small - approximately one impulse per second. Under the influence of reflex influences, their number can be increased or decreased. With an increase in the number of pulses, the tone of the vessels increases - their narrowing occurs. If the number of pulses decreases, the vessels are expanding.

The parasympathetic nervous system has a vasodilatory influence only on the vessels of some organs. In particular, it expands the language vessels, salivary glands and genital organs. Only these three organs have double innervation: sympathetic (vasoconstrictor) and parasympathetic (vasodilant).

Brief description of vesselot centers.

Neurons of the sympathetic nervous system, on the processes of which the pulses of the vessels go, are located in the side horns of the spinal cord. The level of activity of these neurons depends on the influences of the overlying departments of the central nervous system.

In 1871, F.V. Vysyannikov showed that neurons are under the oblong brain, under the influence of which the vessels are due to the influence of vessels. This center was called vascular. Its neurons are concentrated in the oblong brain at the bottom of the IV ventricle near the nucleus of the wandering nerve.

In the vesaled center there are two departments: press, or vasoconducting, and depressor, or vasodilator. In case of irritation of the neurons of the pressing center, the narrowing of the vessels and an increase in blood pressure occurs, and with irritation of the depressor - the expansion of the vessels and a decrease in blood pressure. The neurons of the depressor center at the time of their excitement cause a decrease in the tone of the pressing center, as a result of which the number of toning pulses going to the vessels decreases and their expansion occurs.

The pulses from the brain vesseloring center come to the side horns of the spinal cord gray, where the neurons of the sympathetic nervous system are located, forming the spinal cord thoroughbuilding center. From it on the fibers of the sympathetic nervous system, pulses go to the muscles of vessels and cause them to reduce them, as a result of which the narrowing of the vessels occurs.

Reflex regulation of tons of vessels.

There are own cardiovascular reflexes and conjugate.

Conjugated cardiovascular reflexes are divided into two groups: exterorceceptive (arising from irritation of receptors lying on the surface of the body) and interoreceptive (arising from irritation of the receptors of internal organs).

Any action on the body comes from exterorceptors primarily increases the tone of the vessels and causes a pressing reaction. Thus, with mechanical or pain irritation of the skin, the reflex narrowing of the vessels occurs with a strong irritation of the vessels and other receptors.

The redistribution of blood in the body and blood supply to the working bodies is associated with vascular reactions.

Especially important in the redistribution of blood in the body have reactions arising from irritation of interoreceptors and receptors from working muscles. The provision of working muscles with oxygen and nutrients occurs due to the extension of the vessels and an increase in blood supply to working muscles. The extension of the vessels occurs when chemoreceptors are irritating - mat, milk, coal and other acids, which cause a decrease in tone and extension of vessels. More blood flows into extended vessels and the power of the working muscles improves. But at the same time, the redistribution of blood takes place. Under the influence of efferent pulses from the Vasomotor Center, the narrowing of the vessels of non-working organs occurs. Extended vessels of working bodies are insensitive to these vasoconstrictor impulses.

Humoral regulation of the tone of vessels.

Chemicals affecting the lumen of vessels are divided into vasoconstrictors and vasodilators.

Adrenaline and norepinephrine have the most powerful vesseloring effect. They cause narrowing of arteries and arterioles of the skin, lungs and abdominal organs. At the same time, they cause an expansion of heart and brain vessels.

Adrenaline is a biologically very active drug and acts in very low concentrations. 0.0002 mg of adrenaline per 1 kg of body weight is enough to cause blood pressure narrowing and raising blood pressure. Adrenaline vesseloring effect is carried out by different paths. It acts directly on the wall of the vessels and reduces the membrane potential of its muscle fibers, increasing excitability and creating conditions for the rapid appearance of excitation. Adrenaline affects the hypothalamus and leads to strengthening the stream of vasocomponing pulses and an increase in the amount of vasopressin released.

Indirect influence on the change in the lumen of the vessels and maintaining constancy of blood pressure has a renin in kidney. Its education increases with a decrease in the amount of sodium in the blood and reduce blood pressure. Interacting with plasma protein by hypertension, it forms a biologically active substance of hypertension, causing the narrowing of the vessels and an increase in blood pressure.

Sumorizing factors include serotonin, which, narrowing the damaged vessel, helps reduce bleeding.

Acetylcholine, anti-sinngenogen, medulin, bradykin, foremeady, histamine, and others have vasodilatory action.

Acetylcholine causes the expansion of small arteries and a decrease in blood pressure. Its action briefly, since in the blood, it is quickly destroyed.

Anti-shiftsingen is constantly in the blood along with hypertension, balancing its action. The oscillations of its amount in the blood are aimed at maintaining constancy of blood pressure.

In kidneys, medulus is formed, causing extension of vessels.

Bradykin is formed in the tissues of the pancreas and submandibular glands, in the lungs, leather, etc. It lowers the tone of the smooth arteriole musculature, contributing to a decrease in blood pressure.

Histamine is formed in the process of metabolism in skeletal muscles, in the skin, in the walls of the stomach and intestines, etc., the arterioles are expanded under the influence of histamine and the control of the capillaries increases, and therefore a large amount of blood is delayed. Therefore, blood inflows decreases to the heart, which leads to a drop in blood pressure in the arteries.

This regulation is ensured by a complex mechanism. sensitive (afferent), central and efferent links.

5.2.1. Sensitive link.Vascular receptors - angioceptor- in its function are divided into baroreceptors(press receptors) reacting to the change in blood pressure, and chemoreceptors, sensitive to changes in the chemical composition of blood. Their greatest clusters are in main reflexogenic zones:aortic, sylocarotide, in the vessels of the pulmonary circle of blood circulation.

Stimulus baroreceptors It is not pressure as such, but the speed and degree of stretching the wall of the vessel with pulse or increasing blood pressure fluctuations.

Chemoreceptors React to change in blood concentration O 2, CO 2, H +, some inorganic and organic substances.

Reflexes arising from the recipes of the cardiovascular system and determining the regulation of relationships within exactly this system are called own (system) circulatory reflexes.With an increase in irritation force in the response, in addition to the cardiovascular system, it is involved breath. It will be already conjugated reflex.The existence of conjugated reflexes allows the blood circulation system to quickly and adequately adapt to the changing conditions of the inner environment of the body.

Bulbar level regulation.The alternating brain vessels is the main center for maintaining the tone of vessels and reflex regulation of blood pressure.

Depressor zoneit helps to reduce blood pressure by reducing the activity of sympathetic vesseloring fibers, thereby causing the extension of the vessels and the drop in peripheral resistance, as well as by attenuating the sympathetic stimulation of the heart, that is, reduction of cardiac output.

1. AUTORGULATION

2. Nervous regulation

3. Humoral regulation

Nervous regulation The vascular tone is carried out by the vegetative nervous system, which has a vasoconstrictor and vasodilating effect.

Humoral regulation It is carried out by substances of system and local action. The systemic substances include calcium, potassium, sodium ions, hormones:

Calcium ions cause narrowing vessels potassium ions Expanding action.

The ability to expand the vessels possess biologically active substances and local hormones, such as histamine, serotonin, bradykin, prostaglandins.

Vasopressin - increases the tone of smooth muscle cells arteriole, causing the narrowing of the vessels;

Adrenalin on artery and arterioles of the skin, digestive, kidney and lung organs vasoconstrictor influence; on the vessels of skeletal muscles, smooth "muscles of bronchi - expandingSupporting the redistribution of blood in the body. In physical tension, emotional excitement, it helps to increase blood flow through skeletal muscles, brain, heart. The effect of adrenaline and norepinephrine on the vascular wall is determined by the existence of different types of adrenoreceptors - α and β, which are areas of smooth muscle cells with special chemical sensitivity. Both types of receptors are usually available in vessels. The interaction of mediators with an α-adrenoreceptor leads to a reduction in the vessel wall, with a β-receptor - to relaxation.

Tyroxin - stimulates energy processes and causes the narrowing of blood vessels;

Aldosterone It is produced in the cortical layer of adrenal glands. Aldosterone has an unusually high ability to strengthen the inverse sodium suction in the kidneys, salivary glands, the digestive system, thus changing the sensitivity of the vessel walls to the influence of adrenaline and norepinephrine.

Vasopressin It causes the narrowing of the arteries and the arterioles of the abdominal organs and the lungs. However, as under the influence of adrenaline, the brain and heart vessels react to this hormone expansion, which helps to improve nutrition and brain tissue, and heart muscle.

In the nervous and endocrine regulation, hemodynamic mechanisms of short-term action, intermediate and long-term action are distinguished. To mechanisms short-termactions include circulatory reactions of nervous origin - baroreptor, chemoreceptor, reflex on Izhemia CNS. Their development occurs within a few seconds. Intermediate(in time) Mechanisms encompass changes in transcapillary metabolism, relaxation of the stressed vessel wall, reaction of the renin-angiotensin system. For the inclusion of these mechanisms, moments are required, and for maximum development - hours. Regulatory mechanisms longactions affect the ratio between intravascular blood volume ivessel capacity. This is carried out by means of a transcapillary fluid exchange. In this process, the renal regulation of fluid volume, vasopressin and aldosterone is involved.

Regional blood circulation

Due to the heterogeneity of the structure of different organs, the differences in them exchange processes, as well as various functions, it is customary to distinguish between regional (local) blood circulation in separate organs and fabrics: coronary, brain, pulmonary, etc.

Circulation in the heart

Mammal myocardium gets blood on two crown (coronary) arteries - The right and left, the mouths of which are located in the Lukovice Aorta. The capillary myocardial network is very thick: the number of capillaries is approaching muscle fibers.

The conditions of blood circulation in heart vessels differ significantly from the conditions of circulation in the vessels of other organs of the body. Rhythmic pressure fluctuations in the cavities of the heart and changing its shape and sizes during the heart cycle have a significant effect on the bloodstream. So, at the time of the systolic voltage of the ventricles, the heart muscle squeezes the vessels in it, so blood flow weaken, Oxygen delivery to tissues is reduced. Immediately after the end of Systole, blood supply to the heart increases. Tachycardia can be a problem for coronary perfusion, because most of the flow occurs during the diastolic period, which becomes shorter when the CSS increases.

Brain circulation

Circulation brain is more intense than other organs. The brain requires constant feeding O 2 and the influx of blood to the brain is relatively independent of the IOC and the activities of the vegetative nervous nervous
Systems. The cells of the highest sections of the CNS with insufficient supply with oxygen cease to function earlier than the cells of other organs. The cessation of blood flow to the brain of the cat by 20 C causes the complete disappearance of electrical processes in the crust of large hemispheres, and the cessation of blood flow on 5 min leads to irreversible damage to the brain cells.

About 15% of the blood of each heart ejection into a large circle of blood circulation enters the brain vessels. With intensive mental operation, brain blood supply increases to 25%, in children - up to 40%. Brain artery are muscular type vessels with abundant adrenergic innervation, which allows them to change the clearance in wide limits. The number of capillaries is the greater than more intense tissue metabolism. In the gray substance, the capillaries are much curious than in white.

The blood flowing from the brain enters the veins forming the sines in the solid shell of the brain. In contrast to other parts of the body, the venous brain system does not perform the capacitive function, the brain vein capacity does not change, so possible significant venosal pressure drops.

The effectors of brain blood flow control are intracerebral arteries and artery soft brain shellwho are characterized specific functional features. With a change in total blood pressure under certain limits, the intensity of the brain circulation remains constant. This is carried out by changing the resistance in the arteries of the brain, which are narrowed by increasing the overall blood pressure and expand when it is reduced. In addition to such an autoregument of blood flow, brain protection from high blood pressure and pulsation redundancy occurs mainly due to the characteristics of the structure of the vascular system of this area. These features are that in the course of the vascular bed there are numerous bends ("Siphons"). The bends smooth the pressure drops and the pulsating nature of blood flow.

Brain Bloodstock is also determined moiogenic auto regulationin which blood flow is relatively constant in a wide range of MAP, from about 60 mm mercury pillars up to 130 mm Hg.

Brain blood flow also reacts on changes in local metabolism. Increasing neuron activity and enhanced consumption O 2 causes local extension of vessels.

Gaza blood Also strongly affect brain-blooded blood flow. For example, dizziness with hyperventilation is caused by the narrowing of the brain vessels as a result of an increase in the output from the blood CO 2 and the decrease in Paco 2. In this case, the flow of nutrients decreases, the efficiency of the brain is disturbed. On the other hand, the increase in Paco 2 is the cause of cerebral vasodilation. PAO 2 variations have a small effect, but with severe hypoxia (low PAO 2), pronounced cerebral vasodulation occurs.

Lonantic circulation

The blood supply to the lungs is carried out by the pulmonary and bronchial vessels. Pulmonary vessels make up a small circle of blood circulation and perform mainly gas exchange function Between blood and air. Bronchial vessels Provided food fabrics and belong to K. big circle blood circulation ..

A feature of a small circle of blood circulation is the relatively small length of its vessels, less (about 10 times compared with the large circuit) resistance to the stream of blood, the subtlety of the walls of arterial vessels and the almost immediate contact of the capillaries with air of pulmonary alveol. Due to smaller resistance, blood pressure in the arteries of a small circle is 5-6 times less than the pressure in the aorta. Erythrocytes pass through the lungs about 6 s, while in the metabolic capillaries of 0.7 s.

Blood circulation in the liver

Liver gets at the same time, arterial and venous blood. Arterial blood comes on the hepatic artery, venous - from a gorgeous vein from the digestive tract, pancreas and spleen. Common outflow of blood from the liver to the hollow vein is carried out on the hepatic veins. Hence, deoxygenated blood From the digestive tract, the pancreas and spleen returns to the heart only after passing even further through the liver. Such a feature of the blood supply to the liver, called the name portal blood circulation, associated with digestion and execution of the barrier function. Blood in the portal system passes through two capillary networks. The first network is located in the walls of the digestive, pancreas, spleen, it provides the absorption, excretory and motor functions of these organs. The second network of capillaries is located directly in the liver parenchyma. It provides its exchange and excretory functions, preventing the body intoxication by the products formed in the digestive tract.

The studies of the Russian surgeon and physiologist N. V. Ekka showed that if the blood from the portal vein is sent directly to the hollow vein, that is, bypassing the liver, the body poisoning will occur with fatal.

The feature of the microcirculation in the liver is the close relationship between the ramifications of the portal vein and the actual hepatic artery with the formation of the liver sinusoid capillaries, whose membranes are directly adjacent hepatocytes. A large surface of blood contact with hepatocytes and slow blood flow in sinusoid capillaries create optimal conditions for exchange and synthetic processes.

Renal blood circulation

Through each human kidney for 1 min, about 750 ml of blood passes, which is 2.5 times the mass of the organ and is 20 times greater than the blood supply to many other organs. During the day through the kidneys, about 1000 liters of blood passes. Consequently, with this volume of blood supply, the entire amount of blood in the body of blood for 5-10 minutes passes through the kidneys.

Blood enters the kidneys on renal arteries. They branched to K. mozgovoy and cortova substance, the latter - on cluster (bringing) and yuCstaglomerular. Bringing the arterioles of the cortical substance branches on the capillaries that form vascular gloves Renal Taurus of Cork Nephron. Clotter capillaries are collected in the gloming arterioles. Bringing and submitting arteries differ in diameter by about 2 times (submitting less). As a result of this ratio in the capillaries of the glomeruli of cortex nephrons, an unusually high blood pressure occurs - up to 70-90 mm Hg. Art., What serves as the basis for the appearance of the first phase of urging, which is the nature of filtration of substance from the blood plasma into the kidney channel system.

Extinguishing arterioles, having passed a short way, again disintegrate on the capillaries. The capillaries tear the tubes of the nephron, forming a peritobullic capillary network. It " secondary "capillaries. In contrast to the "primary" blood pressure in them is relatively low - 10-12 mm Hg. Art. Such low pressure contributes to the occurrence of the second phase of urica, which is the nature of the process of reverse absorption of the fluid and dissolved in it the substances of the tubules into the blood. Both arterioles - bringing and endowing vessels - can change their lumen as a result of a reduction or relaxation of smooth muscle fibers available in their walls.

Unlike the total peripheral blood flow, the influx of blood to the kidneys is not controlled by metabolic factors. The renal blood flow is most strongly subject to the effects of autoregulation and a sympathetic tone. In most cases, the renal blood flow is relatively constant, because miogenic auto regulation operates in the range from 60 mm Hg. up to 160 mm Hg. The increase in the tone of the sympathetic nervous system occurs during exercise Or if the baroreceptor reflex, which stimulates the decrease in blood pressure as a result of renal vasoconstriction.

Circulation in the spleen

The spleen is an important hematopoietic and protective organ, which is strongly variating in volume and mass, depending on the number of blood deposited in it and the activity of blood formation processes. Splezenka takes part in elimination of extending or damaged red blood cells and neutralization of ex- and endogenous antigens that were not detained lymphatic nodes and penetrated the bloodstream.

Vascular spleen system due to a peculiar structure plays a significant role in the function of this organ. The feature of blood circulation in the spleen is due the atypical structure of her capillaries. The end branches of the capillaries have tassels ending with blind extensions with holes. Through these holes, blood passes into the pulp, and from there in the sinuses having holes in the walls. Due to this feature of the structure of the spleen, like a sponge, can deposit a large amount of blood.

Blood supply of organs depends on the size of the vessels, their tone and the amount of blood ejected in them. Therefore, when considering the regulation of the function of vessels, first of all, we must talk about the mechanisms for maintaining a vascular tone and the interaction of the heart and blood vessels.

Efferent innervation of vessels. Vascular clearance is mainly regulated by the sympathetic nervous system. Her nerves on their own or as part of mixed motor nerves suitable for all arteries and arteriols and have a vasoconstrictor influence (Vasoconstriction). Bright demonstration of this effect are the experiments of the Bernard Claude, spent on the rabbit's ear vessels. In these experiments, a sympathetic nerve was cut on the neck of the rabbit, after which the redness of the operated side of the operated side was observed and a slight increase in its temperature due to the extension of the vessels and an increase in the blood supply of the ear. The irritation of the peripheral end of a converted sympathetic nerve caused the narrowing of the vessels and the broadband of the ear.

Under the influence of the sympathetic nervous system of the muscles of vessels is in a state of reduction - tonic voltage.

In the natural conditions of the body's life, the change in the lumen of most vessels occurs due to the change in the number of pulses going on the sympathetic nerves. The frequency of these pulses is small - approximately 1 impulse per second. Under the influence of reflex influences, their number can be increased or decreased. With an increase in the number of pulses, the tone of the vessels increases - their narrowing occurs. If the number of pulses decreases, the vessels are expanding.

Parasympathetic nervous system has a vasodilatory effect ( vasodilatation) Only on the vessels of some organs. In particular, it expands the vessels of the language, salivary glands and genital organs. Only these three organs have double innervation: sympathetic (vasoconstrictor) and parasympathetic (vasodilant).

Characteristic of the vessels center. Neurons of the sympathetic nervous system, on the processes of which the pulses of the vessels go, are located in the side horns of the spinal cord. The level of activity of these neurons depends on the effects of the overlying CNS departments.

In 1871 F.V. Ovsyannikov showed that neurons are under the oblong brain, under the influence of which the vessels are escalating. This center got a name vasomotory. Its neurons are concentrated in the oblong brain at the bottom of the IV ventricle near the nucleus of the wandering nerve.

In the vesaled center there are two departments: press, or vasoconducting, and depressor, or vasodilator. With irritation of neurons pressor The center is the narrowing of the vessels and the increase in blood pressure, and when irritating de pressing - Expansion of vessels and decrease in blood pressure. The neurons of the depressor center at the time of their excitement cause a decrease in the tone of the pressing center, as a result of which the number of toning pulses going to the vessels decreases and their expansion occurs.

Reflex regulation of vessel tone. There are own and conjugate cardiovascular reflexes.

Own vascular reflections Called signals from the receptors of the vessels themselves. Especially important physiological records are receptors that are in the aortic arc and carotid sine. Impulses from these receptors take part in the regulation of blood pressure.

Conjugated vascular reflections There are in other organs and systems and are manifested mainly by the increase in blood pressure. So, with mechanical or pain irritation of the skin, strong irritation of the visual and other receptors there comes a reflex narrowing of vessels and an increase in blood pressure.

Humoral regulation of the tone of vessels. Chemicals affecting the lumen of vessels are divided into vasoconstrictors and vasodilators.

The most powerful vasoconducting The vehicles of the brain layer of the adrenal glands have the action - adrenalin and noradrenalinas well as the rear lobe of the pituitary vasopressin.

Adrenaline and norepinephrine narrowing the arteries and arterioles of the skin, abdominal organs and lungs, and Vasopressin acts mainly on arterioles and capillaries.

Adrenaline is a biologically very active drug and acts in very low concentrations. 0.0002 mg of adrenaline per 1 kg of body weight is enough to cause vessels and an increase in blood pressure. Adrenaline vesseloring effect is carried out by different paths. It acts directly on the wall of the vessels and reduces the membrane potential of its muscle fibers, increasing excitability and creating conditions for the rapid appearance of excitation. Adrenaline affects the hypothalamus and leads to strengthening the stream of vasocomponing pulses and an increase in the amount of vasopressin released.

The number of humoral vesseloring factors belongs serotonin produced in the intestinal mucosa and in some parts of the brain. Serotonin is also formed during the collapse of platelets. Serotonin narrows the vessels and prevents bleeding from the affected vessel. In the second phase of blood coagulation, developing after the formation of thrombus, serotonin expands the vessels.

Special vasoconstrictor factor - renin It is formed in the kidneys, and those in more quantities, the lower the blood supply to the kidneys. For this reason, after partially squeezing the renal arteries in animals there is a persistent increase in the blood pressure due to the narrowing of the arteriole. Renin is a proteolytic enzyme. Renin himself does not cause the narrowing of the vessels, but, entering blood, breaks away and 2 -Globulin plasma - angiotensinogenand turns it into relatively lowactive - angiotenzine I.The latter under the influence of a special angiotensin-converting enzyme turns into a very active vesseloring agent - angiotensin II.

In the conditions of normal blood supply to the kidneys, a relatively small amount of renin is formed. In large quantities, it is produced when the blood pressure level is dropped throughout the vascular system. If you lower blood pressure from a dog by bleeding, then the kidneys will be aligned into blood increased quantity Renin, which will contribute to the normalization of blood pressure.

The opening of the renin and the mechanism of its vasoconductive action represents a large clinical interest: it explained the cause of high blood pressure concomitant of some kidney diseases (hypertension of renal origin).

Vasteransior Action has medulin, prostaglandins, bradykin, acetylcholine, histamine.

Medulin It is produced in the brain layer of the kidney and is a lipid.

Currently, education in many tissues of the body of a number of vessels, called name prostandinov. This name is given because for the first time these substances were found in the seed fluid in men, and it was assumed that they were formed prostate. Prostaglandins are derivatives of unsaturated fatty acids.

From the submandibular, pancreas, from the lungs and some other organs, an active vasodilator polypeptide was obtained bradykinin. It causes the relaxation of the smooth muscles of arteriol and lowers the level of blood pressure. Bradykinin appears in the skin under the action of heat and is one of the factors resulting in the expansion of vessels during heating. It is formed when splitting one of the globulins of blood plasma under the influence of an enzyme in the tissues.

Refers to vasodilators acetylcholine (Ah), which is formed in the endings of parasympathetic nerves and sympathetic vasodilators. It quickly collapses in the blood, so its action on the vessels in physiological conditions is purely local.

The vasodilatory substance is also histamine, Forming in the mucous membrane of the stomach and intestines, as well as in many other organs, in particular in the skin during its irritation and in skeletal muscles during operation. Histamine expands the arterials and increases the bloodstream capillaries. With the introduction of 1-2 mg of histamine in Vienna a cat, despite the fact that the heart continues to work with the previous force, the level of blood pressure drops quickly due to the reduction of blood flow to the heart: a very large amount of the animal blood is concentrated in capillaries, mainly the abdominal cavity. Reducing the blood pressure and circulatory disorder is similar to what they occur with a large blood loss. They are accompanied by a violation of the CNS activities due to brain circulation disorder. The combination of listed phenomena is combined with the concept of "shock".

Heavy disorders arising in the body with the introduction of large doses of histamine, are called histamine shock.

The enhanced formation and action of histamine explains the reaction of the redness of the skin. This reaction is caused by the effect of various irritations, such as rubbing the skin, thermal exposure, ultraviolet radiation.