Histohematic barrier - it is a set of morphological structures, physiological and physico-chemical mechanisms that function as a whole and regulate the flow of substances between the blood and organs.

Histohematic barriers are involved in maintaining the homeostasis of the body and individual organs. Due to the presence of histohematic barriers, each organ lives in its own special environment, which can differ significantly from the composition of individual ingredients. Particularly powerful barriers exist between the brain, the blood and tissue of the gonads, the blood and moisture of the chambers of the eye, the blood of the mother and fetus.

Histohematic barriers of various organs have both differences and a number of common features buildings. Direct contact with blood in all organs has a barrier layer formed by the endothelium of blood capillaries. In addition, the HGB structures are the basement membrane (middle layer) and adventitial cells of organs and tissues (outer layer). Histohematic barriers, changing their permeability to various substances, can limit or facilitate their delivery to the organ. For a number of toxic substances, they are impenetrable, which manifests their protective function.

The most important mechanisms that ensure the functioning of blood-histohematic barriers are further considered using the example of the blood-brain barrier, the presence and properties of which the doctor often has to take into account when using drugs and various effects on the body.

Blood-brain barrier

Blood-brain barrier is a set of morphological structures, physiological and physico-chemical mechanisms that function as a single whole and regulate the flow of substances between the blood and brain tissue.

The morphological basis of the blood-brain barrier is the endothelium and basement membrane of the cerebral capillaries, interstitial elements and glycocalyx, neuroglia astrocytes, covering the entire surface of the capillaries with their legs. The movement of substances across the blood-brain barrier involves the transport systems of the endothelium of the capillary walls, including vesicular transport of substances (pino- and exocytosis), transport through channels with or without the participation of carrier proteins, enzyme systems that modify or destroy incoming substances. It has already been mentioned that specialized water transport systems function in the nervous tissue using the aquaporin proteins AQP1 and AQP4. The latter form water channels that regulate the formation of cerebrospinal fluid and the exchange of water between the blood and brain tissue.

Brain capillaries differ from capillaries in other organs in that endothelial cells form a continuous wall. At the points of contact, the outer layers of endothelial cells merge, forming the so-called "tight junctions".

The blood-brain barrier performs protective and regulatory functions for the brain. It protects the brain from the action of a number of substances formed in other tissues, foreign and toxic substances, participates in the transport of substances from the blood to the brain and is an important participant in the mechanisms of homeostasis of the intercellular fluid of the brain and cerebrospinal fluid.

The blood-brain barrier is selectively permeable to various substances. Some biologically active substances, such as catecholamines, practically do not pass through this barrier. The only exceptions are small areas of the barrier on the border with the pituitary gland, pineal gland and some areas where the permeability of the blood-brain barrier for many substances is high. In these areas, channels and interendothelial gaps penetrating the endothelium were found, through which substances from the blood penetrate into the extracellular fluid of the brain tissue or into themselves. The high permeability of the blood-brain barrier in these areas allows biologically active substances (cytokines,) to reach those neurons of the hypothalamus and glandular cells, on which the regulatory circuit of the neuroendocrine systems of the body closes.

A characteristic feature of the functioning of the blood-brain barrier is the possibility of changing its permeability for a number of substances under different conditions. Thus, the blood-brain barrier is able, by regulating permeability, to change the relationship between the blood and the brain. Regulation is carried out by changing the number of open capillaries, blood flow velocity, changes in the permeability of cell membranes, the state of the intercellular substance, the activity of cellular enzyme systems, pino- and exocytosis. The permeability of the BBB can be significantly impaired in conditions of ischemia of the brain tissue, infection, the development of inflammatory processes in the nervous system, and its traumatic injury.

It is believed that the blood-brain barrier, while creating a significant obstacle to the penetration of many substances from the blood into the brain, at the same time well passes the same substances formed in the brain in the opposite direction - from the brain into the blood.

The permeability of the blood-brain barrier for various substances is very different. Fat-soluble substances tend to cross the BBB more easily than water-soluble substances.. Easily penetrate oxygen, carbon dioxide, nicotine, ethyl alcohol, heroin, fat-soluble antibiotics ( chloramphenicol and etc.)

Lipid-insoluble glucose and some essential amino acids cannot pass into the brain by simple diffusion. Carbohydrates are recognized and transported by special transporters GLUT1 and GLUT3. This transport system is so specific that it distinguishes between stereoisomers of D- and L-glucose: D-glucose is transported, but L-glucose is not. Glucose transport into the brain tissue is insensitive to insulin, but is inhibited by cytochalasin B.

Carriers are involved in the transport of neutral amino acids (for example, phenylalanine). For the transfer of a number of substances, active transport mechanisms are used. For example, due to active transport against concentration gradients, Na + , K + ions, the amino acid glycine, which acts as an inhibitory mediator, are transported.

Thus, the transfer of substances using various mechanisms is carried out not only through plasma membranes but also through the structures of biological barriers. The study of these mechanisms is necessary to understand the essence of regulatory processes in the body.

Histohematic barrier(from the Greek ἱστός - "cloth" and αἷμα - "blood"), internal barrier, histiocytic barrier- common name physiological mechanisms functioning between blood and tissue fluid, regulating metabolic processes between blood and tissues, thereby ensuring the constancy of the composition and physico-chemical properties of the tissue fluid, as well as delaying the transition of foreign substances into it from the blood and intermediate metabolic products.

The morphological substrate of the histohematic barrier is the capillary wall, which consists of:

1) fibrin film;

2) endothelium on the basement membrane;

3) a layer of pericytes;

4) adventitia.

In the body, they perform two functions - protective and regulatory.

Protective function associated with the protection of tissue from incoming substances (foreign cells, antibodies, endogenous substances, etc.).

Regulatory function is to ensure a constant composition and properties internal environment organism, conduction and transmission of molecules of humoral regulation, removal of metabolic products from cells.

The histohematic barrier can be between tissue and blood and between blood and fluid.

The main factor affecting the permeability of the histohematic barrier is permeability. Permeability- the ability of the cell membrane of the vascular wall to pass various substances. It depends on:

1) morphofunctional features;

2) activities of enzyme systems;

3) mechanisms of nervous and humoral regulation.

In the blood plasma there are enzymes that can change the permeability of the vascular wall. Normally, their activity is low, but in pathology or under the influence of factors, the activity of enzymes increases, which leads to an increase in permeability. These enzymes are hyaluronidase and plasmin. Nervous regulation is carried out according to the non-synaptic principle, since the mediator enters the capillary walls with a fluid current. sympathetic division of the autonomic nervous system reduces permeability, and parasympathetic - increases.

Humoral regulation is carried out by substances that are divided into two groups - increasing permeability and decreasing permeability.

The mediator acetylcholine, kinins, prostaglandins, histamine, serotonin, and metabolites that shift the pH to an acidic environment have an increasing effect.

Heparin, norepinephrine, Ca ions can have a lowering effect.

Histohematic barriers are the basis for the mechanisms of transcapillary exchange.

Thus, the work of histohematic barriers big influence render the structure of the vascular wall of the capillaries, as well as physiological and physico-chemical factors.

The histohematic barrier ensures the relative stability of the composition, physical, chemical and biological properties of the interstitial fluid, creating an adequate environment for the performance of specific functions of cellular elements.

There are blood-brain, hemato-ophthalmic, hematolabyrinthic barrier, blood-gonadal barrier, hematoliquor, hematolymphatic, hematopleural, hematosynovial, etc.

The main structural elements of the histohematic barrier are blood capillaries with structural features of their endothelial cells, structural features of the ground substance (glycosaminoglycans), the basal membrane of blood vessels, in the brain - the perivascular legs of astroglia, which run to the capillaries.

Histohematic barriers are considered as self-regulating systems subject to nervous and humoral influences, intended for the normal course of metabolic processes in organs and tissues.

Hematohepatic barrier(from the Greek αἷμα - "blood" and ἧπαρ - "liver") - determines the relative constancy of the composition and properties of the internal environment of the liver. It has a dual function - regulatory and protective; the first function - regulates the penetration into the liver of biogenic physiologically active substances; the second is protection against penetration into the liver of substances alien to its function.

Hematolabyrinth barrier- a specialized barrier formation, the selective permeability of which is an essential factor in the normal function of sound and spatial analyzers. Determines the penetration into the labyrinth of both physiologically active biogenic and various medicinal substances.

Hematolyenal barrier lien- "spleen") is located between the blood and tissue fluid of the spleen; has regulatory and protective functions.

Hematoliquor barrier(from Greek αἷμα - "blood" and Latin liquor- "fluid") - one of the histohematic barriers, which is a protective barrier between the cerebrospinal fluid and blood. Performs a protective function - in healthy individuals, substances containing iodine, nitric acid, salicylic acid, methylene blue, colloids, immune bodies, antibiotics do not pass from the blood into the cerebrospinal fluid. Easily pass alcohol, chloroform, strychnine, morphine hydrochloride, tetanus toxin. The regulatory function of the hematoliquor barrier is manifested in a change in the permeability of the barrier for some biologically active substances present in the blood. Such selective permeability can serve as a method of regulation functional state brain.

Hematoophthalmic barrier(from the Greek αἷμα - "blood" and ὀφθαλμός - "eye") is a physiological mechanism that performs a barrier function in relation to the transparent media of the eye. Regulates the relative constancy of the composition of the intraocular fluid, affects the metabolism of the cornea, lens and other tissues of the eye. In the formation of intraocular fluid, the most important role belongs to the endothelium of capillaries and the epithelium of the ciliary body - they are the main anatomical substrates of the barrier through which the exchange between blood and intraocular fluid takes place.

Hematopulmonary barrier(from Greek αἷμα - "blood" and Latin pulmo- “lung”) regulates and protects the relative constancy of the composition and properties of the internal environment of the lungs. Physiologically adequate lung permeability is an essential factor in their normal function. Substances alien to the body accumulate in the lungs extremely slowly. Along with this, antibiotics during electrophoretic inhalation accumulate in a significant amount in the respiratory organs. This applies to specific antibiotics used in the treatment of lung diseases.

Hematorenal barrier(from Greek αἷμα - "blood" and Latin ren- "kidney") is located between the blood and vascular system kidneys; has regulatory and protective functions. Participates in the regulation of water and electrolyte metabolism.

Hematotesticular barrier(from Greek αἷμα - "blood" and Latin testiculus- "testicle") - morphologically, the structure of the hemato-testicular barrier includes the outer wall of the vessels, the own membrane of the convoluted tubules, sustentocytes (Sertoli cells), the protein coat and interstitial tissue. It has a high resistance, which many authors compare with that of the blood-brain barrier.

Blood-brain barrier(from the Greek αἷμα - "blood" and ἐγκέφαλος - "brain") or brain barrier- histohematic barrier between blood and cerebrospinal fluid. It has a dual function - regulatory and protective. The functions of the barrier depend on the choroid plexuses of the brain, the permeability of the meningeal membranes, mesodermal structures and ultrastructural elements in the form of membrane mechanisms. The transfer of substances from the blood to the brain occurs in two ways: directly to the brain and through the cerebrospinal fluid. The permeability of the blood-brain barrier for physiologically active biogenic substances is determined by the regulatory function. The penetration of substances foreign to the brain is associated with a violation of the protective function of the blood-brain barrier, which in some cases leads to the development of pathological processes.

liver barrier- the general name of the physiological and biochemical processes carried out in the liver, aimed at neutralizing toxic substances formed as a result of metabolism or coming from outside.

Spinal cord, spinal nodes: microscopic structure, tissue components, sources of development, functions. Own apparatus of the spinal cord: components of the reflex arc. Outside, it is covered with a pia mater, which contains blood vessels that penetrate into the substance of the brain.

It consists of two symmetrical halves, delimited from each other in front by a deep median fissure, and behind by a connective tissue septum. In the center is the central canal of the spinal cord, which is located in the gray matter, lined with ependyma, contains cerebrospinal fluid, which is in constant motion. The halves of the gray matter are connected by the anterior and posterior commissures of the gray matter.

The inner part of the spinal cord is darker - this is its gray matter. On the periphery of it is a lighter white matter. The gray matter on the cross section of the brain is seen in the form of a butterfly. The protrusions of the gray matter are called horns. There are anterior, or ventral, posterior, or dorsal, and lateral, or lateral, horns. The gray matter of the spinal cord consists of multipolar neurons, non-myelinated and thin myelinated fibers, and neuroglia.

Gray matter The spinal cord consists of neuron bodies, non-myelinated and thin myelinated fibers, and neuroglia. The main component of gray matter, which distinguishes it from white, are three types of multipolar neurons.

The first type of neurons is phylogenetically older and is characterized by a few long, straight and weakly branching dendrites (isodendritic type). The second type of neurons has a large number of strongly branching dendrites that intertwine, forming "tangles" (idiodendritic type).

The third type of neurons, in terms of the degree of development of dendrites, occupies an intermediate position between the first and second types.

During the development of the spinal cord, neurons are formed from the neural tube, grouped in 10 layers, or in plates. For a person, the following architectonics of the indicated plates is characteristic: plates I-V correspond to the posterior horns, plates VI-VII - to the intermediate zone, plates VIII-IX - to the anterior horns, plate X - to the zone of the near-central canal. The gray matter of the brain consists of multipolar neurons.

Gray matter neurons are divided into:

1) internal. Completely (with processes) located within the gray matter. They are intercalary and are found mainly in the posterior and lateral horns. There are:

a) Associative. located within one half.

b) Commissural. Their processes extend into the other half of the gray matter.

2) beam neurons. They are located in the posterior horns and in the lateral horns. form nuclei or are located

diffusely. Their axons enter the white matter and form bundles of nerve fibers in an ascending direction. They are inserts.

3) radicular neurons. They are located in the lateral nuclei (kernels of the lateral horns), in the anterior horns. Their axons

extend beyond the spinal cord and form the anterior roots of the spinal cord. In the superficial part of the posterior horns there is a spongy layer, which contains a large number of small intercalary neurons.

white matter The spinal cord is a collection of longitudinally oriented predominantly myelinated fibers.

The white matter contains ascending (sensitive) pathways, which are located in the posterior cords and in the peripheral part of the lateral horns. They are separated by glial-connective tissue septa. In the white matter, the anterior, lateral and posterior cords are distinguished. Descending nerve pathways (motor) are located in the anterior cords and in the inner part of the lateral cords.

Bundles of nerve fibers that communicate between different parts of the nervous system are called pathways of the spinal cord.

In the middle part of the posterior horn of the spinal cord is located own nucleus of the posterior horn. It consists of bundle cells, the axons of which, passing through the anterior white commissure to the opposite side of the spinal cord into the lateral funiculus of the white matter, form the ventral spinocerebellar and spinothalamic pathways and go to the cerebellum and optic tubercle. The cells of the nucleus provide exteroceptive sensitivity.

Diffusely located in the posterior horns intercalary neurons. These are small cells whose axons terminate within the gray matter of the spinal cord of the same (associative cells) or opposite (commissural cells) side.

Dorsal nucleus, or Clark's thoracic nucleus, consists of large cells with branched dendrites. At the base of the posterior horns. Their axons cross the gray matter, enter the lateral funiculus of the white matter of the same side and as part of tr. spinocerebellaris posterior and tr. spinothalamicus posterior ascend to the cerebellum and thalamus. The cells of this nucleus provide proprioceptive sensitivity.

medial intermediate nucleus contains large beam neurons, is located in the intermediate zone, its cell neurites join the ventral spinocerebellar tract of the same side, the lateral intermediate nucleus is located in the lateral horns and is a group of associative cells of the sympathetic reflex arc. The axons of these cells leave the spinal cord together with the somatic motor fibers as part of the anterior roots and separate from them in the form of white connecting branches of the sympathetic trunk. Their axons go to the white matter of the same half and form tr. spinocerebellaris anterior. Provides visceral sensation.

The largest neurons of the spinal cord are located in the anterior horns, they also form nuclei from the bodies of nerve cells, the roots of which form the bulk of the fibers of the anterior roots.

As part of the mixed spinal nerves, they enter the periphery and end with motor endings in the skeletal muscles.

Lateral intermediate nucleus refers to the autonomic nervous system. In the thoracic and upper lumbar regions it is the sympathetic nucleus, and in the sacral region it is the nucleus of the parasympathetic nervous system. It contains an intercalary neuron, which is the first neuron of the efferent link of the reflex arc. This is a radicular neuron. Its axons exit as part of the anterior roots of the spinal cord.

The anterior horns contain large motor nuclei, which contain motor radicular neurons having short dendrites and a long axon. The axon exits as part of the anterior roots of the spinal cord, and then goes as part of the peripheral mixed nerve, represents motor nerve fibers and is pumped at the periphery by a neuromuscular synapse on skeletal muscle fibers. They are effectors. Forms the third effector link of the somatic reflex arc.

In the anterior horns secrete medial group of nuclei. It is developed in the thoracic region and provides innervation to the muscles of the body.

Lateral group of nuclei located in the cervical and lumbar regions and innervates the upper and lower limbs.

The gray matter of the spinal cord contains a large number of diffuse bundle neurons (in the posterior

horns). Their axons go into the white matter and immediately divide into two branches that go up and down. Branches through 2-3 segments of the spinal cord return back to the gray matter and form synapses on the motor neurons of the anterior horns. These cells form own apparatus of the spinal cord, which provides a connection between adjacent 4-5 segments of the spinal cord, due to which a response of a muscle group is provided (an evolutionarily developed protective reaction).

Regeneration. Very poorly regenerates gray matter. Regeneration of white matter is possible, but the process is very long.

Histohematic barriers.

concept histohematic barriers proposed to designate barrier structures between blood and organs. Unlike external

Among the barriers that separate the internal environment of the body, its tissues and cellular structures from the external environment, histohematic barriers are internal, separating blood from tissue fluid. Histohematic barriers are understood as a complex of physiological mechanisms that regulate metabolic processes between blood and tissues, thereby ensuring the constancy of the composition and physicochemical properties of tissue fluid, as well as delaying the transfer of foreign substances from the blood into it.

Histohematic barriers, due to not only selective, but also changing permeability, regulate the supply of necessary plastic and energy materials to cells from the blood and the timely outflow of cellular metabolic products. Thus, these structural and functional mechanisms ensure the constancy of the internal environment. Histohematic barriers in various tissues and organs have significant differences, and some of them, due to a certain specialization, acquire a special vital role. These specialized barriers include blood-brain(between blood and brain tissue) hematoophthalmic(between blood and intraocular fluid) barriers, which are distinguished not only by high selectivity of permeability, but also deprive the barrier tissues immunological tolerance(see below). As a result of damage to these barriers, the macromolecular structures of the barrier tissues are perceived by the immunological system as "foreign" for the body, "unfamiliar" to the immune system, and an immune response is formed against the own tissue structures of the brain or eye / called autoimmune.

Permeability histohematic barriers depends on the chemical structure of the molecules of the transferred substances, on their physicochemical properties. So, for lipid-soluble substances, histohematic barriers are more permeable, since such molecules more easily pass through the lipid layers of cell membranes. According to the peculiarities of permeability for proteins at the blood-tissue level, all histohematic barriers are divided into three groups: insulating, partially insulating and non-insulating. TO insulating barriers include: blood-brain, hematoliquor, hematoneuronal (at the level of the peripheral nervous system), hematotesticular, lens barrier of the eye. TO partially insulating include barriers at the level of the bile capillaries of the liver, the adrenal cortex, the pigment epithelium of the eye between the vascular and retinal membranes, the hemato-ophthalmic barrier at the level of the ciliary processes of the eye, the barriers of the thyroid gland and the end lobes of the pancreas. non-insulating barriers, although they allow the protein to penetrate from the blood into the interstitial fluid, however, limit its transport into the microenvironment and cytoplasm of parenchymal cells. Such barriers exist in the myocardium, skeletal muscle ah, adrenal medulla, parathyroid glands.

The main functions of histohematic barriers are protective and regulatory. Protective function is to delay barriers

the transition of harmful or excessive substances of an endogenous nature, as well as foreign molecules from the blood into the interstitial environment and the microenvironment of cells. At the same time, not only the vascular wall itself with its selective permeability, but also the cellular-colloidal structures of the interstitium prevent the entry of such substances into the microenvironment of cells. If there was a penetration of large-molecular foreign substances into the interstitial space and they did not undergo adsorption, phagocytosis and decay here, then they enter the lymph, and not the cellular microenvironment. Lymph in this regard is like a "second line of defense", since it provides the neutralization of foreign substances, realizing the mechanisms of immunity.

Regulatory function Histohematic barriers implies a wide variety of processes, the ultimate goal of which is the regulation of metabolism and cell functions. Histohematic barriers regulate the composition and properties of the microenvironment of cells, providing it necessary quantity certain nutrients. These barriers control the supply of humoral information to the cells about the state of vital activity in other organs, and biologically active substances and hormones coming from the blood through the barrier to the cells change their metabolism and functions adequately to the general needs of the body.

The main structural element of histohematic barriers is the wall of blood capillaries. Morphological and functional features of endothelial cells, intercellular ground substance and basement membrane determine the permeability of the barrier. The substances contained in the blood can penetrate the barrier in two ways (Fig. 2.5.): transcellular(through endothelial cells) and paracellularly (through the intercellular ground substance). Transcellular transport substances is determined by the properties of the cell membrane of endotheliocytes and can be passive(i.e. along a concentration or electrochemical gradient without consuming energy) and active(against the energy cost gradient). Transcellular transport of substances can also be carried out with the help of pinocytosis, i.e. the process of active absorption by cells of fluid bubbles or colloidal solutions. The membrane of endothelial cells has pores and fenestra, which are also involved in the transcellular transport of substances. Endothelial cells around the entire perimeter are covered with a thin layer of a substance containing glycosaminoglycans in its composition and, accordingly, significantly affecting the permeability. The transfer of substances through endothelial cells depends on the state of metabolism in endotheliocytes. An important role is played by blood platelets absorbed by endothelial cells for trophic purposes.

Paracellular transport or the transfer of substances through intercellular gaps filled with the main substance, enveloping the fibrous structures of the fibrillar protein, is possible for molecules different sizes(from 2 to 30 microns), since the sizes of intercellular gaps in capillaries are not the same. The state of permeability between

Fig.2.5. Transport of substances through the capillary wall.

Er - erythrocytes, EC - endothelial cells, L - leukocytes.

cell spaces, as well as transcellular transport, depends on the metabolism of endotheliocytes.

The binding membrane of the capillaries of different organs has an unequal thickness, and in some tissues it is discontinuous. This barrier structure plays the role of a filter that allows molecules of a certain size to pass through. The basement membrane contains glycosaminoglycans that can reduce the degree of polymerization and adsorb enzymes that increase the permeability of the barrier. Outside, in the basement membrane, there are process cells - pericytes. There is no exact information about the function of these cells; it is assumed that they play a supporting role and produce the main substance of the basement membrane.

The permeability of histohematic barriers changes under the influence of the autonomic nervous system (sympathetic influences reduce permeability) and humoral factors. In addition to hormones circulating in the blood, for example, corticosteroids, tissue biologically active substances and enzymes, formed both by the endothelial cells themselves and by the cellular elements of the interstitial space, play the main role in changes in the permeability of histohematological barriers. Among these substances, it is necessary to name hyaluronidase - an enzyme that causes depolymerization of hyaluronic acid of the main substance of intercellular spaces and sharply increases the permeability of barriers, biogenic amines - serotonin (reducing permeability) and histamine (increasing it), heparin - inhibiting hyaluronidase and reducing permeability, cyto-

kinases - activating plasminogen and barrier permeability. Increase the permeability of barriers and metabolites that cause a pH shift, such as lactic acid.

Histohematic barrier It is the barrier between blood and tissue. They were first discovered by Soviet physiologists in 1929. The morphological substrate of the histohematic barrier is the capillary wall, which consists of:

1) fibrin film;

2) endothelium on the basement membrane;

3) a layer of pericytes;

4) adventitia.

In the body, they perform two functions - protective and regulatory.

Protective function associated with the protection of tissue from incoming substances (foreign cells, antibodies, endogenous substances, etc.).

Regulatory function is to ensure a constant composition and properties of the internal environment of the body, the conduction and transmission of molecules of humoral regulation, the removal of metabolic products from cells.

The histohematic barrier can be between tissue and blood and between blood and fluid.

1) morphofunctional features;

2) activities of enzyme systems;

3) mechanisms of nervous and humoral regulation.

In the blood plasma there are enzymes that can change the permeability of the vascular wall. Normally, their activity is low, but in pathology or under the influence of factors, the activity of enzymes increases, which leads to an increase in permeability. These enzymes are hyaluronidase and plasmin. Nervous regulation is carried out according to the non-synaptic principle, since the mediator enters the capillary walls with a fluid current. The sympathetic division of the autonomic nervous system reduces permeability, while the parasympathetic division increases it.

Humoral regulation is carried out by substances that are divided into two groups - increasing permeability and decreasing permeability.

The mediator acetylcholine, kinins, prostaglandins, histamine, serotonin, and metabolites that shift the pH to an acidic environment have an increasing effect.

Heparin, norepinephrine, Ca ions can have a lowering effect.

Histohematic barriers are the basis for the mechanisms of transcapillary exchange.

Thus, the structure of the vascular wall of capillaries, as well as physiological and physicochemical factors, greatly influence the work of histohematic barriers.

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Anatomical properties
1. Three-component focal arrangement of nerve centers. The lowest level of the sympathetic department is represented by the lateral horns from the VII cervical to III-IV lumbar vertebrae, and the parasympathetic - the cross

Physiological properties
1. Features of the functioning of the autonomic ganglia. The presence of the phenomenon of multiplication (the simultaneous occurrence of two opposite processes - divergence and convergence). Divergence - divergence

Functions of the sympathetic, parasympathetic and metsympathetic types of the nervous system
The sympathetic nervous system innervates all organs and tissues (stimulates the work of the heart, increases the lumen of the respiratory tract, inhibits secretory, motor and suction

General ideas about the endocrine glands
Endocrine glands- specialized bodies, which do not have excretory ducts and secrete into the blood, cerebral fluid, lymph through the intercellular gaps. Endo

Properties of hormones, their mechanism of action
There are three main properties of hormones: 1) the distant nature of the action (the organs and systems that the hormone acts on are located far from the place of its formation); 2) strict with

Synthesis, secretion and excretion of hormones from the body
Biosynthesis of hormones is a chain of biochemical reactions that form the structure of a hormonal molecule. These reactions proceed spontaneously and are genetically fixed in the corresponding endocrine systems.

Regulation of the activity of the endocrine glands
All processes occurring in the body have specific regulatory mechanisms. One of the levels of regulation is intracellular, acting at the cell level. Like many multistage biochemical

Anterior pituitary hormones
The pituitary gland occupies a special position in the system of endocrine glands. It is called the central gland, because due to its tropic hormones, the activity of other endocrine glands is regulated. pituitary gland -

Middle and posterior pituitary hormones
In the middle lobe of the pituitary gland, the hormone melanotropin (intermedin) is produced, which affects the pigment metabolism. The posterior pituitary gland is closely related to the supraoptic

Hypothalamic regulation of pituitary hormone production
Neurons of the hypothalamus produce neurosecretion. Neurosecretion products that promote the formation of hormones of the anterior pituitary gland are called liberins, and those that inhibit their formation are called statins.

Hormones of the epiphysis, thymus, parathyroid glands
The epiphysis is located above the superior tubercles of the quadrigemina. The meaning of the epiphysis is extremely controversial. Two compounds have been isolated from its tissue: 1) melatonin (takes part in the regulation

Thyroid hormones. iodinated hormones. thyrocalcitonin. Thyroid dysfunction
The thyroid gland is located on both sides of the trachea below the thyroid cartilage, has a lobular structure. The structural unit is a follicle filled with colloid, where iodine-containing protein is located.

Hormones of the pancreas. Pancreatic dysfunction
The pancreas is a mixed function gland. The morphological unit of the gland is the islets of Langerhans, they are mainly located in the tail of the gland. islet beta cells produce

Pancreatic dysfunction
A decrease in insulin secretion leads to the development diabetes, the main symptoms of which are hyperglycemia, glucosuria, polyuria (up to 10 liters per day), polyphagia (increased appetite), poly

Adrenal hormones. Glucocorticoids
The adrenal glands are paired glands located above the upper poles of the kidneys. They have important vitality. There are two types of hormones: cortical hormones and medulla hormones.

Physiological significance of glucocorticoids
Glucocorticoids affect the metabolism of carbohydrates, proteins and fats, enhance the formation of glucose from proteins, increase the deposition of glycogen in the liver, and are insulin antagonists in their action.

Regulation of glucocorticoid formation
An important role in the formation of glucocorticoids is played by corticotropin of the anterior pituitary gland. This influence is carried out on the principle of direct and feedback: corticotropin increases glucocorticoid production

Adrenal hormones. Mineralocorticoids. sex hormones
Mineralocorticoids are formed in the glomerular zone of the adrenal cortex and take part in the regulation of mineral metabolism. These include aldosterone deoxycorticosterone

Regulation of mineralocorticoid formation
The secretion and formation of aldosterone is regulated by the renin-angiotensin system. Renin is formed in special cells of the juxtaglomerular apparatus of the afferent arterioles of the kidney and is released

Significance of epinephrine and norepinephrine
Adrenaline performs the function of a hormone, it enters the blood constantly, under various conditions of the body (blood loss, stress, muscle activity), its formation increases and is excreted.

sex hormones. Menstrual cycle
The gonads (testes in men, ovaries in women) are glands with a mixed function, the intrasecretory function is manifested in the formation and secretion of sex hormones, which are directly

The menstrual cycle has four periods
1. Pre-ovulation (from the fifth to the fourteenth day). The changes are due to the action of follitropin, in the ovaries there is an increased formation of estrogens, they stimulate the growth of the uterus, growth with

Hormones of the placenta. The concept of tissue hormones and antihormones
Placenta - unique education that links the mother to the fetus. It performs numerous functions, including metabolic and hormonal. It synthesizes the hormones of two

The concept of higher and lower nervous activity
Lower nervous activity is an integrative function of the spinal and brainstem, which is aimed at the regulation of vegetative-visceral reflexes. With its help, they provide

The formation of conditioned reflexes
For education conditioned reflexes certain conditions are required. 1. The presence of two stimuli - indifferent and unconditional. This is due to the fact that an adequate stimulus will cause b

Inhibition of conditioned reflexes. The concept of a dynamic stereotype
This process is based on two mechanisms: unconditional (external) and conditional (internal) inhibition. Unconditional inhibition occurs instantly due to the termination of the

The concept of the types of the nervous system
The type of the nervous system directly depends on the intensity of the processes of inhibition and excitation and the conditions necessary for their development. The type of the nervous system is a set of processes, n

The concept of signaling systems. Stages of formation of signaling systems
The signaling system is a set of conditioned reflex connections of the body with environment, which subsequently serves as the basis for the formation of higher nervous activity. By time about

Components of the circulatory system. Circles of blood circulation
The circulatory system consists of four components: the heart, blood vessels, organs - the blood depot, regulation mechanisms. The circulatory system is a component of the

Morphofunctional features of the heart
The heart is a four-chambered organ, consisting of two atria, two ventricles and two auricles. It is with the contraction of the atria that the work of the heart begins. The mass of the heart in an adult

Physiology of the myocardium. The conduction system of the myocardium. Properties of atypical myocardium
The myocardium is represented by striated muscle tissue, consisting of individual cells - cardiomyocytes, interconnected by means of nexuses, and forming the muscle fiber of the myocardium. So about

Automatic heart
Automation is the ability of the heart to contract under the influence of impulses that arise in itself. It was found that nerve impulses can be generated in atypical myocardial cells

Energy supply of the myocardium
For the heart to work as a pump, a sufficient amount of energy is needed. The process of providing energy consists of three stages: 1) education; 2) transport;

ATP-ADP-transferases and creatine phosphokinase
ATP by active transport with the participation of the enzyme ATP-ADP-transferase is transferred to the outer surface of the mitochondrial membrane and with the help of the active center of creatine phosphokinase and Mg ions deliver

Coronary blood flow, its features
For the full-fledged work of the myocardium, a sufficient supply of oxygen is necessary, which is provided by the coronary arteries. They begin at the base of the aortic arch. The right coronary artery supplies blood

Reflex influences on the activity of the heart
The so-called cardiac reflexes are responsible for the two-way communication of the heart with the central nervous system. Currently, there are three reflex influences - own, conjugated, non-specific. own

Nervous regulation of the activity of the heart
Nervous regulation is characterized by a number of features. 1. The nervous system has a starting and corrective effect on the work of the heart, providing adaptation to the needs of the body.

Humoral regulation of the activity of the heart
Factors of humoral regulation are divided into two groups: 1) substances of systemic action; 2) substances of local action. Systemic agents include

Vascular tone and its regulation
Vascular tone, depending on the origin, can be myogenic and nervous. Myogenic tone occurs when some vascular smooth muscle cells begin to spontaneously generate nerve

Functional system that maintains a constant level of blood pressure
A functional system that maintains the value of blood pressure at a constant level is a temporary set of organs and tissues that is formed when indicators deviate in order to

The essence and significance of the processes of respiration
Breathing is the most ancient process by which regeneration is carried out. gas composition the internal environment of the body. As a result, organs and tissues are supplied with oxygen, and give away

Apparatus for external respiration. The value of the components
In humans, external respiration is carried out with the help of a special apparatus, the main function of which is the exchange of gases between the body and external environment. Apparatus for external respiration

Mechanism of inhalation and exhalation
In an adult, the respiratory rate is approximately 16–18 breaths per minute. It depends on the intensity of metabolic processes and the gas composition of the blood. Respiratory

Concept of breathing pattern
Pattern - a set of temporal and volumetric characteristics of the respiratory center, such as: 1) respiratory rate; 2) the duration of the respiratory cycle; 3)

Physiological characteristics of the respiratory center
By modern ideas the respiratory center is a collection of neurons that provide a change in the processes of inhalation and exhalation and adaptation of the system to the needs of the body. Allocate nes

Humoral regulation of respiratory center neurons
For the first time, humoral regulation mechanisms were described in the experiment of G. Frederick in 1860, and then studied by individual scientists, including I. P. Pavlov and I. M. Sechenov. G. Frederick spent

Nervous regulation of neuronal activity of the respiratory center
Nervous regulation is carried out mainly by reflex pathways. There are two groups of influences - episodic and permanent. There are three types of constants: 1) from peripheral x

Homeostasis. biological constants
The concept of the internal environment of the body was introduced in 1865 by Claude Bernard. It is a collection of body fluids that bathe all organs and tissues and take part in metabolic processes.

The concept of the blood system, its functions and significance. Physico-chemical properties of blood
The concept of the blood system was introduced in the 1830s. H. Lang. Blood is a physiological system that includes: 1) peripheral (circulating and deposited) blood;

Blood plasma, its composition
Plasma is the liquid part of the blood and is a water-salt solution of proteins. Consists of 90-95% water and 8-10% solids. The composition of the dry residue includes inorganic and organic

Physiology of red blood cells
Erythrocytes are red blood cells that contain the respiratory pigment hemoglobin. These non-nucleated cells are formed in the red bone marrow and destroyed in the spleen. Depending on the size of

Types of hemoglobin and its significance
Hemoglobin is one of the most important respiratory proteins involved in the transfer of oxygen from the lungs to the tissues. It is the main component of red blood cells, each of them contains

Physiology of leukocytes
Leukocytes - nucleated blood cells, the size of which is from 4 to 20 microns. Their life expectancy varies greatly and ranges from 4–5 to 20 days for granulocytes and up to 100 days

Physiology of platelets
Platelets are nuclear-free blood cells, 1.5–3.5 µm in diameter. They have a flattened shape, and their number in men and women is the same and is 180–320 × 109/l.

Immunological basis for determining the blood group
Karl Landsteiner discovered that the red blood cells of some people stick together with the blood plasma of other people. The scientist established the existence of special antigens in erythrocytes - agglutinogens and suggested the presence in

Antigenic system of erythrocytes, immune conflict
Antigens are high molecular weight polymers of natural or artificial origin that carry signs of genetically alien information. Antibodies are immunoglobulins produced by

Structural components of hemostasis
Hemostasis is a complex biological system of adaptive reactions that maintains the liquid state of blood in the vascular bed and stops bleeding from damaged nipples.

Functions of the hemostasis system
1. Maintaining blood in the vascular bed in a liquid state. 2. Stop bleeding. 3. Mediation of interprotein and intercellular interactions. 4. Opsonic - clean

Mechanisms of platelet and coagulation thrombus formation
The vascular-platelet mechanism of hemostasis ensures that bleeding stops in the smallest vessels, where there is low blood pressure and a small lumen of the vessels. Stopping bleeding can

clotting factors
Many factors take part in the process of blood coagulation, they are called blood coagulation factors, they are contained in blood plasma, formed elements and tissues. Plasma coagulation factors cr

Phases of blood clotting
Blood coagulation is a complex enzymatic, chain (cascade), matrix process, the essence of which is the transition of soluble fibrinogen protein into insoluble fiber protein.

Physiology of fibrinolysis
The fibrinolysis system is an enzymatic system that breaks down the fibrin strands that were formed during blood coagulation into soluble complexes. The fibrinolysis system is fully

The process of fibrinolysis takes place in three phases
During phase I, lysokinase, entering the bloodstream, brings the plasminogen proactivator into an active state. This reaction is carried out as a result of cleavage from the proactivator of a number of amino acids.

The kidneys perform a number of functions in the body.
1. They regulate the volume of blood and extracellular fluid (carry out voloreregulation), with an increase in blood volume, volomoreceptors of the left atrium are activated: the secretion of antidiuretic is inhibited

The structure of the nephron
The nephron is the functional unit of the kidney where urine is produced. The composition of the nephron includes: 1) renal corpuscle (double-walled capsule of the glomerulus, inside

Mechanism of tubular reabsorption
Reabsorption is the process of reabsorption of substances valuable to the body from primary urine. IN various parts nephron tubules absorb various substances. In the proximal

The concept of the digestive system. Its functions
The digestive system is a complex physiological system that ensures the digestion of food, the absorption of nutrients and the adaptation of this process to the conditions of existence.

Types of digestion
There are three types of digestion: 1) extracellular; 2) intracellular; 3) membrane. Extracellular digestion occurs outside the cell

Secretory function of the digestive system
The secretory function of the digestive glands is to release secrets into the lumen of the gastrointestinal tract that take part in the processing of food. For their formation, cells must receive

Motor activity of the gastrointestinal tract
Motor activity is the coordinated work of the smooth muscles of the gastrointestinal tract and special skeletal muscles. They lie in three layers and consist of circularly arranged mice.

Regulation of motor activity of the gastrointestinal tract
A feature of motor activity is the ability of some cells of the gastrointestinal tract to rhythmic spontaneous depolarization. This means that they can be rhythmically excited. in cut

The mechanism of the sphincters
Sphincter - thickening of the smooth muscle layers, due to which the entire gastrointestinal tract is divided into certain sections. There are the following sphincters: 1) cardiac;

Physiology of suction
Absorption - the process of transferring nutrients from the cavity of the gastrointestinal tract into the internal environment of the body - blood and lymph. Absorption occurs throughout the stomach

The mechanism of absorption of water and minerals
Absorption is carried out due to physico-chemical mechanisms and physiological patterns. This process is based on active and passive modes of transport. Structure matters a lot

Mechanisms of absorption of carbohydrates, fats and proteins
Absorption of carbohydrates occurs in the form final products metabolism (mono- and disaccharides) in the upper third of the small intestine. Glucose and galactose are absorbed by active transport, and all

Mechanisms of regulation of absorption processes
The normal function of the cells of the mucous membrane of the gastrointestinal tract is regulated by neurohumoral and local mechanisms. In the small intestine, the main role belongs to the local method,

Physiology of the digestive center
The first ideas about the structure and functions of the food center were summarized by I.P. Pavlov in 1911. According to modern ideas, the food center is a collection of neurons located at different levels

Normal physiology: lecture notes Svetlana Sergeevna Firsova

12. Histohematic barrier and its physiological role

1) fibrin film;

2) endothelium on the basement membrane;

3) a layer of pericytes;

4) adventitia.

In the body, they perform two functions - protective and regulatory.

Protective function associated with the protection of tissue from incoming substances (foreign cells, antibodies, endogenous substances, etc.).

The histohematic barrier can be between tissue and blood and between blood and fluid.

1) morphofunctional features;

2) activities of enzyme systems;

3) mechanisms of nervous and humoral regulation.

In the blood plasma there are enzymes that can change the permeability of the vascular wall. Normally, their activity is low, but in pathology or under the influence of factors, the activity of enzymes increases, which leads to an increase in permeability. These enzymes are hyaluronidase and plasmin. Nervous regulation is carried out according to the non-synaptic principle, since the mediator enters the capillary walls with a fluid current. The sympathetic division of the autonomic nervous system reduces permeability, while the parasympathetic division increases it.

Humoral regulation is carried out by substances that are divided into two groups - increasing permeability and decreasing permeability.

The mediator acetylcholine, kinins, prostaglandins, histamine, serotonin, and metabolites that shift the pH to an acidic environment have an increasing effect.

Heparin, norepinephrine, Ca ions can have a lowering effect.

Histohematic barriers are the basis for the mechanisms of transcapillary exchange.

Thus, the structure of the vascular wall of capillaries, as well as physiological and physicochemical factors, greatly influence the work of histohematic barriers.

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