Capillaries, their types, structure and function. The concept of microcirculation
1. According to the diameter of the lumen
Narrow (4-7 microns) are found in the striated muscles, lungs, and nerves.
Wide (8-12 microns) are in the skin, mucous membranes.
Sinusoidal (up to 30 microns) are found in the hematopoietic organs, endocrine glands, liver.
Lacunas (more than 30 microns) are located in the columnar zone of the rectum, the cavernous bodies of the penis.
2. According to the structure of the wall
Somatic, characterized by the absence of fenestra (local thinning of the endothelium) and holes in the basement membrane (perforations). Located in the brain, skin, muscles.
Fenestrated (visceral type), characterized by the presence of fenestra and the absence of perforations. They are located where the processes of molecular transfer occur most intensively: glomeruli of the kidneys, intestinal villi, endocrine glands).
Perforated, characterized by the presence of fenestra in the endothelium and perforations in the basement membrane. This structure facilitates the transition through the cell capillary wall: sinusoidal capillaries of the liver and hematopoietic organs.
Capillary function- the exchange of substances and gases between the lumen of the capillaries and the surrounding tissues is carried out due to the following factors:
1. Thin wall of capillaries.
2. Slow blood flow.
3. Large area of contact with surrounding tissues.
4. Low intracapillary pressure.
The number of capillaries per unit volume in different tissues is different, but in each tissue there are 50% of non-functioning capillaries that are in a collapsed state and only blood plasma passes through them. When the load on the body increases, they begin to function.
There is a capillary network that is enclosed between two vessels of the same name (between two arterioles in the kidneys or between two venules in the portal system of the pituitary gland), such capillaries are called the “miraculous network”.
When several capillaries merge, they form postcapillary venules or postcapillaries, with a diameter of 12-13 microns, in the wall of which there is a fenestrated endothelium, there are more pericytes. When postcapillaries merge, they form collecting venules, in the middle shell of which smooth myocytes appear, the adventitial shell is better expressed. Collecting venules continue into muscle venules, in the middle shell of which contains 1-2 layers of smooth myocytes.
Venule function:
· Drainage (receipt of metabolic products from the connective tissue into the lumen of the venules).
Blood cells migrate from the venules into the surrounding tissue.
The microcirculation includes arteriolo-venular anastomoses (AVA)- These are the vessels through which blood from the arterioles enters the venules bypassing the capillaries. Their length is up to 4 mm, diameter is more than 30 microns. AVAs open and close 4 to 12 times per minute.
AVAs are classified into true (shunts) through which arterial blood flows, and atypical (semi-shunts) through which mixed blood is discharged, tk. when moving along the half-shunt, a partial exchange of substances and gases with the surrounding tissues occurs.
Functions of true anastomoses:
Regulation of blood flow in capillaries.
Arterialization of venous blood.
Increased intravenous pressure.
Functions of atypical anastomoses:
· Drainage.
· Partial exchange.
Heart
It is the central organ of blood and lymph circulation. Due to the ability to contract, it sets the blood in motion. The wall of the heart consists of three layers: endocardium, myocardium and epicardium.
Development of the heart
It occurs as follows: in the cranial pole of the embryo, on the right and on the left, endocardial tubes are formed from the mesenchyme. At the same time, thickenings appear in the visceral sheets of the splanchnotome, which are called myoepicardial plates. The endocardial tubes are inserted into them. The two formed heart rudiments gradually approach and merge into a single tube consisting of three shells, so a single-chamber model of the heart appears. Then the tube grows in length, it acquires an S-shape and is divided into anterior section- ventricular and posterior - atrial. Later, septa and valves appear in the heart.
The structure of the endocardium
The endocardium is the inner shell of the heart, which lines the atria and ventricles, consists of four layers and in its structure resembles the wall of an artery.
Layer I is the endothelium, which is located on the basement membrane.
Layer II - subendothelial, represented by loose connective tissue. These two layers are analogous to the inner lining of the arteries.
Layer III - muscular-elastic, consisting of smooth muscle tissue, between the cells of which elastic fibers are located in the form of a dense network. This layer is the "equivalent" of the middle lining of the arteries.
Layer IV - outer connective tissue, consisting of loose connective tissue. It is similar to the outer (adventitial) membrane of the arteries.
There are no vessels in the endocardium, so its nutrition occurs by diffusion of substances from the blood in the cavities of the heart.
Due to the endocardium, atrioventricular valves and valves of the aorta and pulmonary artery are formed.
The structure of the vessels The cardiovascular system(CCC) consists of the heart, blood and lymphatic vessels. Vessels in embryogenesis are formed from the mesenchyme. They are formed from the mesenchyme of the marginal zones of the vascular strip of the yolk sac or the mesenchyme of the embryo. In late embryonic development and after birth, vessels form by budding from capillaries and post-capillary structures (venules and veins). Blood vessels are subdivided into main vessels (arteries, veins) and vessels of the microvasculature (arterioles, precapillaries, capillaries, postcapillaries and venules). In the main vessels, blood flows at a high speed and there is no exchange of blood with tissues; in the vessels of the microcirculatory bed, blood flows slowly for a better exchange of blood with tissues. All organs of the cardiovascular system are hollow and, except for the vessels of the microcirculatory system, contain three membranes: 1. The inner membrane (intima) is represented by the inner endothelial layer. Behind it is the subendothelial layer (PBST). The subendothelial layer contains a large number of poorly differentiated cells migrating into the middle shell, and delicate reticular and elastic fibers. In muscular arteries, the inner membrane is separated from the middle membrane by an internal elastic membrane, which is a cluster of elastic fibers. 2. The middle shell (media) in the arteries consists of smooth myocytes, located in a gentle spiral (almost circular), elastic fibers or elastic membranes (in the arteries of the elastic type); In the veins, it may contain smooth myocytes (muscle-type veins) or connective tissue predominates (non-muscle-type veins). In veins, unlike arteries, the middle layer (media) is much thinner than the outer layer (adventitia).
3. The outer shell (adventitia) is formed by the RVST. In the arteries of the muscular type, there is a thinner than the inner - the outer elastic membrane.
Arteries Arteries have 3 shells in the structure of the wall: intima, media, adventitia. Arteries are classified according to the predominance of elastic or muscular elements on the artery: 1) elastic, 2) muscular and 3) mixed type.
In the arteries of the elastic and mixed types, in comparison with the arteries of the muscular type, the subendothelial layer is much thicker. The middle shell in the arteries of the elastic type is formed by fenestrated elastic membranes - an accumulation of elastic fibers with zones of their rare distribution ("windows"). Between them there are layers of RVST with single smooth myocytes and fibroblastic cells. Muscular arteries contain many smooth muscle cells. The farther from the heart, the arteries are located with a predominance of the muscular component: the aorta is of the elastic type, the subclavian artery is of the mixed type, and the brachial artery is of the muscular type. An example of a muscular type is also the femoral artery.
Veins The veins have 3 membranes in their structure: intima, media, adventitia. The veins are divided into 1) non-muscular and 2) muscular (with weak, medium or strong development of the muscular elements of the middle shell). Veins of the non-muscular type are located at the level of the head, and vice versa - veins with a strong development of the muscular membrane on lower limbs. Veins with a well-developed muscular membrane have valves. Valves are formed by the inner lining of the veins. Such a distribution of muscle elements is associated with the action of gravity: it is more difficult to raise blood from the legs to the heart than from the head, therefore, in the head - a muscleless type, in the legs - with a highly developed muscle layer (example - femoral vein). The blood supply to the vessels is limited to the outer layers of the media and the adventitia, while in the veins the capillaries reach the inner shell. The innervation of the vessels is provided by autonomic afferent and efferent nerve fibers. They form the adventitious plexus. Efferent nerve endings reach mainly the outer regions of the middle sheath and are predominantly adrenergic. Afferent nerve endings of baroreceptors that respond to pressure form local subendothelial accumulations in the main vessels.
An important role in the regulation of vascular muscle tone, along with autonomic nervous system, play biologically active substances, including hormones (adrenaline, norepinephrine, acetylcholine, etc.).
Blood Capillaries Blood capillaries contain endothelial cells lying on a basement membrane. The endothelium has a metabolic apparatus, is able to produce a large number of biologically active factors, including endothelins, nitric oxide, anticoagulant factors, etc., which control vascular tone and vascular permeability. Adventitial cells are closely adjacent to the vessels. In the formation of basement membranes of capillaries, pericytes take part, which may be in the cleavage of the membrane. There are capillaries: 1. Somatic type. The lumen diameter is 4-8 µm. The endothelium is continuous, not fenestrated (i.e., not thinned, the fenestra is a window in translation). The basement membrane is continuous and well defined. The layer of pericytes is well developed. There are adventitial cells. Such capillaries are located in the skin, muscles, bones (what is referred to as soma), as well as in organs where it is necessary to protect cells - as part of histohematic barriers (brain, gonads, etc.) 2. Visceral type. Clearance up to 8-12 microns. The endothelium is continuous, fenestrated (the cytoplasm of the endotheliocyte is practically absent in the area of the windows and its membrane is adjacent directly to the basement membrane). All types of contacts predominate between endotheliocytes. The basement membrane is thinned. There are fewer pericytes and adventitial cells. Such capillaries are found in internal organs, such as the kidneys, where urine must be filtered.
3. Sinusoidal type. The lumen diameter is more than 12 µm. The endothelial layer is discontinuous. Endotheliocytes form pores, hatches, fenestra. The basement membrane is discontinuous or absent. There are no pericytes. Such capillaries are necessary where not only the exchange of substances between blood and tissues takes place, but also "cell exchange", i.e. in some organs of blood formation (red bone marrow, spleen), or large substances - in the liver.
Arterioles and precapillaries. Arterioles have a lumen diameter of up to 50 µm. Their wall contains 1-2 layers of smooth myocytes. The endothelium is elongated along the course of the vessel. Its surface is flat. The cells are characterized by a well-developed cytoskeleton, an abundance of desmosomal, locking, and tiled contacts. In front of the capillaries, the arteriole narrows and passes into the precapillary. Precapillaries have a thinner wall. The muscular coat is represented by separate smooth myocytes. Postcapillaries and venules. Postcapillaries have a lumen of smaller diameter than that of venules. The structure of the wall is similar to the structure of the venule. Venules are up to 100 µm in diameter. The inner surface is uneven. The cytoskeleton is less developed. Contacts, mostly simple, in a "butt". Often, the endothelium is higher than in other vessels of the microvasculature. Cells of the leukocyte series penetrate through the wall of the venule, mainly in the zones of intercellular contacts. The outer layers are similar in structure to capillaries. Arterio-venular anastomoses.
Blood may come from arterial systems into the venous, bypassing the capillaries, through arteriolo-venular anastomoses (AVA). There are true AVA (shunts) and atypical AVA (half shunts). In half-shunts, the afferent and efferent vessels are connected through a short, wide capillary. As a result, mixed blood enters the venule. In true shunts, there is no exchange between the vessel and the organ, and arterial blood enters the vein. True shunts are divided into simple (one anastomosis) and complex (several anastomoses). It is possible to distinguish shunts without special locking devices (smooth myocytes play the role of the sphincter) and with a special contractile apparatus (epithelioid cells, which, when swollen, compress the anastomosis, closing the shunt).
Lymphatic vessels. Lymphatic vessels are represented by microvessels of the lymphatic system (capillaries and postcapillaries), intraorganic and extraorganic lymphatic vessels. Lymphatic capillaries begin blindly in tissues, contain a thin endothelium and a thinned basement membrane.
In the wall of medium and large lymphatic vessels there is an endothelium, subendothelial layer, muscular membrane and adventitia. According to the structure of the membranes, the lymphatic vessel resembles a muscular vein. The inner membrane of the lymphatic vessels forms valves, which are an integral attribute of all lymphatic vessels after the capillary section.
clinical significance. 1. In the body, arteries are most sensitive to atherosclerosis, and especially of the elastic and muscular-elastic types. This is due to hemodynamics and the diffuse nature of the trophic supply of the inner membrane, its significant development in these arteries. 2. In the veins, the valve apparatus is most developed in the lower extremities. This greatly facilitates the movement of blood against the hydrostatic pressure gradient. Violation of the structure of the valve apparatus leads to a gross violation of hemodynamics, edema and varicose veins lower limbs. 3. Hypoxia and low molecular weight products of cell destruction and anaerobic glycolysis are among the most powerful factors stimulating the formation of new blood vessels. Thus, areas of inflammation, hypoxia, etc., are characterized by subsequent rapid growth of microvessels (angiogenesis), which ensures the restoration of the trophic supply of the damaged organ and its regeneration.
4. Antiangiogenic factors preventing the growth of new vessels, according to a number of modern authors, could become one of the effective antitumor drug groups. By blocking the growth of blood vessels in rapidly growing tumors, doctors could thereby cause hypoxia and death. cancer cells.
cytohistology.ru
Private histology of the cardiovascular system
Vascular development.
The first vessels appear on the second - third week of embryogenesis in the yolk sac and chorion. From the mesenchyme, an accumulation is formed - blood islands. The central cells of the islets round off and turn into blood stem cells. The peripheral cells of the islet differentiate into the vascular endothelium. Vessels in the body of the embryo are laid a little later; in these vessels, blood stem cells do not differentiate. Primary vessels are similar to capillaries, their further differentiation is determined by hemodynamic factors - these are pressure and blood flow velocity. Initially, a very large part is laid in the vessels, which is reduced.
The structure of the vessels.
In the wall of all vessels, 3 shells can be distinguished:
1. internal
2. middle
3. outer
arteries
Depending on the ratio of muscular elastic components, arteries of the type are distinguished:
elastic
Large main vessels - aorta. Pressure - 120-130 mm / hg / st, blood flow velocity - 0.5 1.3 m / s. The function is transport.
Inner shell:
A) endothelium
flattened polygonal cells
B) subendothelial layer (subendothelial)
It is represented by loose connective tissue, contains stellate cells that perform combi functions.
Middle shell:
Represented by fenestrated elastic membranes. Between them a small number of muscle cells.
Outer shell:
It is represented by loose connective tissue, contains blood vessels and nerve trunks.
muscular
Arteries of small and medium caliber.
Inner shell:
A) endothelium
B) subendothelial layer
B) internal elastic membrane
Middle shell:
Smooth muscle cells predominate, arranged in a gentle spiral. Between the middle and outer shell is the outer elastic membrane.
Outer shell:
Represented by loose connective tissue
Mixed
Arterioles
Similar to arteries. Function - regulation of blood flow. Sechenov called these vessels - taps of the vascular system.
The middle shell is represented by 1-2 layers of smooth muscle cells.
capillaries
Classification:
Depending on diameter:
narrow 4.5-7 microns - muscles, nerves, musculoskeletal tissue
medium 8-11 microns - skin, mucous membranes
sinusoidal up to 20-30 microns - endocrine glands, kidneys
gaps up to 100 microns - found in the cavernous bodies
Depending on the structure:
Somatic - continuous endothelium and continuous basement membrane - muscles, lungs, CNS
The structure of the capillary:
3 layers, which are analogues of 3 shells:
A) endothelium
B) pericytes enclosed in a basement membrane
B) adventitial cells
2. Finistered - have thinning or windows in the endothelium - endocrine organs, kidneys, intestines.
3. perforated - there are through holes in the endothelium and in the basement membrane - hematopoietic organs.
similar to capillaries but have more pericytes
Classification:
● fibrous (muscleless) type
Found in spleen, placenta, liver, bones, meninges. In these veins, the subendothelial layer passes into the surrounding connective tissue.
● muscular type
There are three subtypes:
● Depending on the muscle component
A) veins with weak development of muscle elements, located above the level of the heart, blood flows passively due to its severity.
B) veins with an average development of muscular elements - the brachial vein
C) veins with a strong development of muscular elements, large veins lying below the level of the heart.
Muscular elements are found in all three sheaths
Structure
Inner shell:
Endothelium
Subendothelial layer - longitudinally directed bundles of muscle cells. A valve is formed behind the inner shell.
Middle shell:
Circularly arranged bundles of muscle cells.
Outer shell:
Loose connective tissue, and longitudinally arranged muscle cells.
DEVELOPMENT
The heart is laid at the end of the 3rd week of embryogenesis. Under the visceral sheet of the splanchnotome, an accumulation of mesenchymal cells is formed, which turn into elongated tubules. These mesenchymal accumulations protrude into the cylomic cavity, bending the visceral sheets of the splanchnotome. And the areas are myoepicardial plates. Subsequently, the endocardium, myoepicardial plates, myocardium and epicardium are formed from the mesenchyme. The valves develop as duplication of the endocardium.
studfiles.net
BSMU
Discipline: Histology | commentThe importance of the cardiovascular system (CVS) in the life of the body, and hence the knowledge of all aspects of this area for practical medicine, is so great that cardiology and angiology have separated into the study of this system as two independent areas. The heart and blood vessels are systems that function not periodically, but constantly, therefore, more often than other systems, they are subject to pathological processes. Currently, cardiovascular disease, along with cancer, occupies a leading position in terms of mortality. The cardiovascular system ensures the movement of blood throughout the body, regulates the supply of nutrients and oxygen to tissues and the removal of metabolic products, the deposition of blood.
Classification: I. The central organ is the heart. II. Peripheral department: A. Blood vessels: 1. Arterial link: a) arteries of elastic type; b) muscular arteries; c) mixed arteries. 2. Microcirculatory bed: a) arterioles; b) hemocapillaries; c) venules; d) arteriolo-venular anastomoses 3. Venous link: a) muscular type veins (with weak, medium, strong development of muscular elements; b) non-muscular type veins. B. Lymphatic vessels: 1. Lymphatic capillaries. 2. Intraorganic lymphatic vessels. 3. Extraorganic lymphatic vessels. In the embryonic period, the first blood vessels are laid on the 2nd week in the wall of the yolk sac from the mesenchyme (see the stage of megaloblastic hematopoiesis on the topic "Hematopoiesis") - blood islands appear, the peripheral cells of the islet flatten and differentiate into the endothelial lining, and from the surrounding mesenchyme connective tissue and smooth muscle elements of the vessel wall. Soon, blood vessels are formed from the mesenchyme in the body of the embryo, which are connected to the vessels of the yolk sac. Arterial link - represented by vessels through which blood is delivered from the heart to the organs. The term “artery” is translated as “air-containing”, since at autopsy, researchers often found these vessels empty (not containing blood) and thought that vital “pneuma” or air was spreading through them through the body .. Elastic, muscular and mixed type arteries have a common principle of structure: 3 shells are distinguished in the wall - inner, middle and outer adventitia. The inner shell consists of layers: 1. Endothelium on the basement membrane. 2. Subendothelial layer - snotty fibrous sdt with a high content of poorly differentiated cells. 3. Internal elastic membrane - plexus of elastic fibers. The middle shell contains smooth muscle cells, fibroblasts, elastic and collagen fibers. On the border of the middle and outer adventitial membranes there is an external elastic membrane - a plexus of elastic fibers. The outer adventitial membrane of the arteries is histologically represented by a loose fibrous tissue with vascular vessels and vascular nerves. Features in the structure of varieties of arteries are due to differences in the hemadynamic conditions of their functioning. Differences in structure mainly relate to the middle shell (different ratio of the constituent elements of the shell): 1. Arteries of the elastic type - these include the aortic arch, pulmonary trunk, thoracic and abdominal aorta. Blood enters these vessels in bursts under high pressure and moves at high speed; there is a large pressure drop during the transition of systole - diastole. The main difference from arteries of other types is in the structure of the middle shell: in the middle shell of the above components (myocytes, fibroblasts, collagen and elastic fibers), elastic fibers predominate. Elastic fibers are located not only in the form of individual fibers and plexuses, but form elastic fenestrated membranes (in adults, the number of elastic membranes reaches up to 50-70 words). Due to the increased elasticity, the wall of these arteries not only withstands high pressure, but also smooths out large pressure drops (jumps) during the systole-diastole transitions. 2. Arteries of the muscular type - these include all arteries of medium and small caliber. A feature of the hemodynamic conditions in these vessels is a drop in pressure and a decrease in blood flow velocity. Arteries of the muscular type differ from other types of arteries by the predominance of myocytes in the middle membrane over others. structural components; the inner and outer elastic membranes are clearly defined. Myocytes in relation to the lumen of the vessel are oriented spirally and are found even in the outer shell of these arteries. Due to the powerful muscular component of the middle shell, these arteries control the intensity of the blood flow of individual organs, maintain a falling pressure and push the blood further, which is why muscle-type arteries are also called the "peripheral heart".
3. Mixed type arteries - these include large arteries extending from the aorta (carotid and subclavian arteries). In terms of structure and function, they occupy an intermediate position. The main feature in the structure: in the middle shell, myocytes and elastic fibers are approximately the same (1: 1), there is a small amount of collagen fibers and fibroblasts.
Microcirculatory bed - a link located between the arterial and venous link; provides regulation of blood filling of the organ, metabolism between blood and tissues, deposition of blood in organs. Composition: 1. Arterioles (including precapillary ones). 2. Hemocapillaries. 3. Venules (including post-capillary). 4. Arteriolo-venular anastomoses. Arterioles are vessels that connect arteries to hemocapillaries. They retain the principle of the structure of the arteries: they have 3 membranes, but the membranes are weakly expressed - the subendothelial layer of the inner membrane is very thin; the middle shell is represented by a single layer of myocytes, and closer to the capillaries - by single myocytes. As the diameter increases in the middle shell, the number of myocytes increases, first one, then two or more layers of myocytes are formed. Due to the presence of myocytes in the wall (in the precapillary arterioles in the form of a sphincter), arterioles regulate the blood filling of the hemocapillaries, thereby the intensity of the exchange between the blood and tissues of the organ. Hemocapillaries. The wall of hemocapillaries has the smallest thickness and consists of 3 components - endotheliocytes, basement membrane, pericytes in the thickness of the basement membrane. There are no muscle elements in the composition of the capillary wall, however, the diameter of the inner lumen may change somewhat as a result of changes in blood pressure, the ability of the nuclei of pericytes and endotheliocytes to swell and contract. There are the following types of capillaries: 1. Type I hemocapillaries (somatic type) - capillaries with continuous endothelium and continuous basement membrane, diameter 4-7 µm. They are found in skeletal muscles, in the skin and mucous membranes. Diameter 8-12 microns. There are in the capillary glomeruli of the kidney, in the intestine, in the endocrine glands. 3. Type III hemocapillaries (sinusoidal type) - the basement membrane is not continuous, sometimes absent, and there are gaps between endotheliocytes; diameter 20-30 or more microns, not constant throughout - there are expanded and narrowed areas. The blood flow in these capillaries is slowed down. Available in the liver, hematopoietic organs, endocrine glands. Around the hemocapillaries there is a thin layer of loose fibrous sdt with a high content of poorly differentiated cells, the state of which determines the intensity of exchange between the blood and the working tissues of the organ. The barrier between the blood in the hemocapillaries and the surrounding working tissue of the organ is called the histohematic barrier, which consists of endotheliocytes and the basement membrane. Capillaries can change their structure, rebuild into vessels of a different type and caliber; new branches can form from existing hemocapillaries. Precapillaries differ from hemocapillaries in that in addition to endotheliocytes, basement membrane, pericytes, there are single or groups of myocytes in the wall.
Venules begin as postcapillary venules, which differ from capillaries in having a high content of pericytes in the wall and the presence of valve-like folds of endotheliocytes. As the diameter of the venules increases in the wall, the content of myocytes increases - first single cells, then groups, and finally continuous layers.
Arteriolo-venular anastomoses (AVA) are shunts (or fistulas) between arterioles and venules, i.e. carry out a direct connection and participate in the regulation of regional peripheral blood flow. They are especially abundant in the skin and kidneys. ABA - short vessels, also have 3 shells; there are myocytes, especially many in the middle shell, acting as a sphincter.
VIENNA. A feature of hemodynamic conditions in the veins is low pressure (15-20 mm Hg) and low blood flow rate, which causes a lower content of elastic fibers in these vessels. The veins have valves - a duplication of the inner shell. The number of muscle elements in the wall of these vessels depends on whether the blood moves under the influence of gravity or against it. Non-muscular type veins are found in the dura mater, bones, retina, placenta, in red bone marrow. The wall of muscleless veins is internally lined with endotheliocytes on the basement membrane, followed by a layer of fibrous sdt; there are no smooth muscle cells. Veins of the muscular type with weakly expressed muscular elements are located in the upper half of the body - in the system of the superior vena cava. These veins are usually collapsed. In the middle shell they have a small number of myocytes.
Veins with highly developed muscle elements make up the vein system of the lower half of the body. A feature of these veins is well-defined valves and the presence of myocytes in all three membranes - in the outer and inner membranes in the longitudinal direction, in the middle - in the circular direction.
LYMPHATIC VESSELS begin with lymphatic capillaries (LC). LC, unlike hemocapillaries, begin blindly and have a larger diameter. The inner surface is lined with endothelium, the basement membrane is absent. Under the endothelium is a loose fibrous sdt with a high content of reticular fibers. The diameter of the LC is not constant - there are contractions and expansions. Lymphatic capillaries merge to form intraorganic lymphatic vessels - in structure they are close to veins, because. are in the same hemodynamic conditions. They have 3 shells, the inner shell forms valves; unlike veins, there is no basement membrane under the endothelium. The diameter is not constant throughout - there are expansions at the level of the valves. Extraorganic lymphatic vessels are also similar in structure to veins, but the basal membrane of the endothelium is poorly expressed, sometimes absent. In the wall of these vessels, the internal elastic membrane is clearly distinguished. The middle shell receives special development in the lower extremities.
HEART. The heart is laid at the beginning of the 3rd week of embryonic development in the form of a paired rudiment in the cervical region from the mesenchyme under the visceral sheet of splanchnotomes. Paired strands are formed from the mesenchyme, which soon turn into tubules, from which the inner shell of the heart, the endocardium, is ultimately formed. The sections of the visceral sheet of splanchnotomes that envelop these tubules are called myoepicardial plates, which subsequently differentiate into the myocardium and epicardium. As the embryo develops with the appearance of the trunk fold, the flat embryo folds into a tube - the body, while 2 bookmarks of the heart are in the chest cavity, approach and finally merge into one tube. Further, this tube-heart begins to grow rapidly in length and, not fitting in the chest, forms several bends. Neighboring loops of the curving tube grow together and a 4-chambered heart is formed from a simple tube. HEART - the central organ of the CCC, has 3 shells: inner - endocardium, middle (muscular) - myocardium, outer (serous) - epicardium. The endocardium consists of 5 layers: 1. Endothelium on the basement membrane. 2. Subendothelial layer of loose fibrous tissue with a large number of poorly differentiated cells. 3. Muscular-elastic layer (myocytes are elastic fibers). 4. Elastic muscle layer (myocyte elastic fibers). 5. Outer sdt-th layer (loose fibrous sdt). In general, the structure of the endocardium resembles the structure of the wall of a blood vessel. The muscular membrane (myocardium) consists of 3 types of cardiomyocytes: contractile, conductive and secretory (for structural and functional features, see the topic “Muscular tissues”). The endocardium is a typical serous membrane and consists of layers: 1. Mesothelium on the basement membrane. 2. Superficial collagen layer. 3. Layer of elastic fibers. 4. Deep collagen layer. 5. Deep collagen-elastic layer (50% of the entire thickness of the epicardium). Under the mesothelium in all layers between the fibers there are fibroblasts. CCC regeneration. Vessels, endocardium and epicardium regenerate well. Reparative regeneration of the heart is poor, the defect is replaced by a scar; physiological regeneration is well expressed, due to intracellular regeneration (renewal of worn out organelles). Age-related changes in the cardiovascular system. In the vessels in the elderly and senile age, a thickening of the inner membrane is observed, deposits of cholesterol and calcium salts (atherosclerotic plaques) are possible. In the middle shell of the vessels, the content of myocytes and elastic fibers decreases, the number of collagen fibers and acid mucopolysaccharides increases.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-1.jpg" alt="(!LANG:> Lecture: HISTOLOGY OF THE CARDIOVASCULAR SYSTEM Prof. M. Yu. Kapitonova">!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-2.jpg" alt="(!LANG:> Purpose and objectives: 1. Study the structure various vessels: arteries, veins,"> Purpose and tasks: 1. To study the structure of various vessels: arteries, veins, ICR vessels 2. To identify structural and functional correlations in different parts of the vascular system 3. To compare the structure and ultrastructure of the myocardium and other types of muscle tissue. 4 Give a comparative description of typical and atypical cardiomyocytes 5. Find common and features in the structure of the wall of the heart and large vessels.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-3.jpg" alt="(!LANG:>Scheme cardiovascular systems ">
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-4.jpg" alt="(!LANG:> DEFINITIONS Vascular system = CCC ("> ОПРЕДЕЛЕНИЯ Сосудистая система = ССС (система гемоциркуляции) + !} lymphatic system. CCC = heart + arteries + capillaries + veins. Layers of the vascular wall: tunica intima, tunica media, tunica adventitia. Microvasculature = Vessels visible only under a microscope (less than 0.1 mm in diameter). Microvasculature = arterioles + precapillary arterioles + capillaries + postcapillary venules + venules.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-5.jpg" alt="(!LANG:>Capillaries are the smallest functional units"> Капилляры - это мельчайшие СХЕМА МЦР функциональные единицы кровеносной системы, они вставлены между артериальным и венозным звеном гемоциркуляции. Они ветвятся, образуя мощную сеть, степень развития которой отражает функциональную активность органа и ткани. Мощные капиллярные сети присутствуют в легких, печени, почках, железах. Вместе с артериолами и венулами капилляры составляют микроциркуляторное русло (диаметр его сосудов менее 100 мкм).!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-6.jpg" alt="(!LANG:> Endothelial lining of capillaries The circulatory system has a continuous endothelial lining, represented by one"> Эндотелиальная выстилка капилляров Кровеносная система имеет непрерывную эндотелиальную выстилку, представленную одним слоем эндотелиальных клеток с зазубренными клеточными границами. Снаружи от эндотелия количество клеток и их слоев прогрессивно увеличивается с ростом калибра сосуда.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-7.jpg" alt="(!LANG:> About capillaries: 1. Most cells in the human body"> О капиллярах: 1. Большинство клеток организма человека находятся не более чем на 50 мкм удаленными от капилляров. 2. В организме человека площадь поверхности капилляров около 600 кв. м. 3. Площадь поперечного сечения всех капилляров в 800 раз больше, чем площадь сечения аорты (сравните скорость кровотока в аорте и в капиллярах). 4. Длина капилляра варьирует от 0. 2 5 до 1 мм (последняя цифра характерна для капилляров мышечной ткани). К коре надпочечников, мозговом веществе почки капилляры могут быть длиной до 5 мм. Общая длина всех капилляров тела человека 0 96, 000 км.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-8.jpg" alt="(!LANG:>The capillary contains an inner membrane - tunica intima, represented by endothelial cells lying one layer"> Капилляр содержит внутреннюю оболочку – tunica intima, представленную эндотелиальными клетками, лежащими одним слоем на базальной мембране, в то время как tunica media и tunica adventitia значительно редуцированы. Эндотелиальная клетка выглядит как тонкая изогнутая пластинка с овальным или удлиненным ядром. Обычно клетки вытянуты вдоль оси капилляра и имеют сужающиеся концы. В месте содержания ядра клетка выбухает в просвет капилляра. Клетки соединены между собой соединительными комплексами и содержат множество пиноцитозных пузырьков. Стрелками показаны фенестры. Фенестрированный капилляр, TЭM, x 10, 000!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-9.jpg" alt="(!LANG:>Fenestrated capillary, TEM, x 10,000 Outside endothelium"> Фенестрированный капилляр, TЭM, x 10, 000 Снаружи от эндотелия располагается прерывистый слой клеток перицитов (стрелка), также обернутых листками базальной мембраны. Некоторые авторы считают, что слой перицитов – это редуцированная tunica media. Перициты – это плюрипотентные клетки, которые могут давать начало другим клеткам, таким как фибробласты. При тканевой травме перициты пролиферируют и дифференцируются с образованием новых кровеносных сосудов и соединительнотканных клеток. В стенке капилляра могут присутствовать небольшое количество коллагеновых и эластических волокон, основного вещества, адвентициальных клеток, фибробластов.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-10.jpg" alt="(!LANG:>Classification of capillaries Based on integrity"> Класси- фикация капилляров Основана на целостности эндотелия: они бывают непрерывными, фенестрирован- ными и синусодальным и.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-11.jpg" alt="(!LANG:> Continuous type capillary Continuous capillaries *somatic type) is"> Капилляр непрерывного типа Непрерывные капилляры *соматический тип) – это такие капилляры, у которых эндотелиальные клетки образуют внутреннюю выстилку без каких-либо межклеточных или внутрицитоплазменных дефектов или прерывистостей. Это выстилка не прерывается ни фенестрами, ни порами. Это наиболее распространенный тип капилляров, в которых вещества транспортируются через стенку посредством пиноцитоза. Такие капилляры присутствуют в мышцах, нервной и соединительной тканях. Они играют важную роль в образовании гемато- энцефалического барьера.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-12.jpg" alt="(!LANG:>Fenestrated type capillary Fenestrated capillaries contain pores with a diameter of 60"> Капилляр фене- стрированного типа Фенестрированные капилляры содержат поры диаметром 60 -70 нм в диаметре, которые обеспечивают более быстрый транскапиллярный транспорт, чем микропиноцитоз в непрерывных капиллярах. Фенестры могут быть перекрыты тонкими диафрагмами. Диффузия через фенестры – это самый важный механизм обмена ыеществами между плазмой крови и интерстициальной жидкостью. Такие капилляры присутствуют в почках, кишечнике, эндокринных железах.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-13.jpg" alt="(!LANG:>Sinusoidal capillary type Sinusoidal capillaries have an increased diameter (up to 40 µm) ."> Синусоидальный тип капилляра Синусоидальные капилляры имеют увеличенный диаметр (до 40 мкм). У них прерывистый не только эндотелий, но и окружающая его базальная мембрана. В стенке присутствуют макрофагальные клетки (например, клетки Купфера в капиллярах печени). Прерывистый эндотелий с огромными фенестрами без диафрагм, и прерывистая базальная мембрана обеспечивают усиленный обмен между кровью и тканями. Синусоиды особенно многочисленны в кроветворных органах и печени.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-14.jpg" alt="(!LANG:> CAPILLARY FUNCTIONS 1. Permeability - capillaries serve as a selective barrier"> ФУНКЦИИ КАПИЛЛЯРОВ 1. Проницаемость – капилляры служат в качестве селективного барьера проницаемости (с крупными и мелкими порами). Клинические корреляции: v Проницаемость микрососудов может увеличиваться при определенных условиях: (воспаление, высвобождение биологически !} active substances such as histamine and bradykinin). v This can lead to the development of edema of the perivascular space and increased infiltration of blood cells that migrate from the bloodstream by diapedesis through intercellular junctions.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-15.jpg" alt="(!LANG:>Functions of capillaries: 2. Metabolic functions a) activation (transformation of angiotensin I in angiotensin"> Функции капилляров: 2. Метаболические функции a) активация (превращение angiotensin I в angiotensin II) b) инактивация – превращение норадреналина, серотонина, брадикинина в биологически инертные соединения c) липолиз – расщепление липопротеинов d) Продукция вазоактивных факторов – эндотелинов, VCAM etc. 3. Антитромбогенная функция - служат контейнером для крови, предотвращающим свертывание.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-16.jpg" alt="(!LANG:>There are 4 types of ICR: Types of ICR 1. Conventional"> Существует 4 типа МЦР: Типы МЦР 1. Обычная Precapil- последовательность: Capillary lary артериола - прекапил- Arteriole sphincter лярная артериола (метартериола) – капил- 1 Post- capillary ляр – посткапиллярная Metarte- venule венула – вена. rioles 2. Артерио-венозные 2 Arterio- анастомозы – отсутствие venous Anasto- капилляров, когда обмен 3 mosis не столь существенен и Capillary важнее всего обеспечить Glome- rular быстрый прогон крови. Capil- laries 3. Артериальная чудесная сеть (в почке). 4. Венозная чудесная сеть (в 4 печени и аденогипофизе). Vein!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-17.jpg" alt="(!LANG:> COMPARATIVE CHARACTERISTICS OF CAPILLARS Sign Continuous- Fenestrial- Lymphatic- Sinus- Venous -"> СРАВНИТЕЛЬНАЯ ХАРАКТЕРИСТИКА КАПИЛЛЯРОВ Признак Непрерыв- Фенестри- Лимфати- Синусои- Веноз- Лимф. ный рованный ческий дальный синус капилляр синус Типичная мышцы Большин- Лимфати- Печень, Селе- Лимфа- Локализа- ство ческие селезенка, зенка тические ция внутрен- узлы красный узлы ностей костный мозг Эндоте- Непрерыв- Прерывис- Преры- лий ный тый вистый, с вистый, макрофа- с макро- гами рофа- фагами гами Фенестры нет Много Только в Крупнее нет в эндо- мелких млечных по разме- телии (0. 07 - ходах рам, варь- 0. 1 мкм) ируют (0. 1 -0. 2 mcm) Фагоцитар нет высокая огра- очень ная актив- ничена высокая ность!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-18.jpg" alt="(!LANG:> COMPARATIVE CHARACTERISTICS OF CAPILLARS sign Continuous- Fenestrial- Lymphatic Sinus- Venous- Lymph."> СРАВНИТЕЛЬНАЯ ХАРАКТЕРИСТИКА КАПИЛЛЯРОВ признак Непрерыв- Фенестри- Лимфатич Синусо- Веноз- Лимф. ный рованный еский иды ные синусы капилляр синусы Диаметр Мелкий (6 - Более Варьиру- Наиболее Круп- просвета 10 мкм), 10 мкм), крупный(1 ющий (5 - круп- ный, правиль- 0 -50 мкм), 30 мкм), ный, непра- ный неправи- непра- виль- льный вильный Базаль- Хорошо Скудная, Отсут- ная развита, или отсут- или преры- ствует мембрана непрерыв- ствует отсутст- вистая ная вует Межкле- нет есть, 0. 1 - варьиру- присут- точные 0. 5 мкм ют ствуют простран- ства перициты присут- отсут- м. б. в отсут- ствуют печени ствуют Соедини- Присутст- Присут- Обычно Отсутств Отсутст- Нет тельные вуют ствуют отсут- уют, кро- вуют данных комплек- ствуют ме селе- сы зенки!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-19.jpg" alt="(!LANG:>"> Сравнительная характеристика кровеносных сосудов Капил- Постка- Собираю- Мышеч- Средние Крупные ляры пилляр- щие(пери- ные вены ные цитарные) венулы венулы) Диаметр 5 -12 мкм 12 -30 30 -50 мкм 50 мкм-3 3 мм-1 >1 cм просвета(8 мкм 40 мкм мм см 3 cм средний и 20 мкм 1 мм 0. 5 cм диапазон) Толщина 1 мкм 2 мкм Нет 0. 1 мм 0. 5 мм 1. 5 мм стенки данных Гладком - - +/- + (много ышечные в адвен- клетки тиции) Эластиче - - +/- + ++ ские волокна Пери- + ++(непол ++++(полн - - циты ный ый слой) слой) Vasa - - - ++++ vasorum!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-20.jpg" alt="(!LANG:> Comparative characteristics of blood vessels"> Сравнительная характеристика кровеносных сосудов Капил- Посткап Собираю- Мышеч- Средние Крупные ляры илляр- щие ные вены ные венулы (перици- тарные) Иннерва- - - +++ ция Лимфати - - +/- +++ ческие сосуды Кров. дав- 22 Нет 12 5 3 (м. б. от- ление у данных рицатель- взрослых ным у Hg мм сердца) Скрость 0. 1 Нет 0. 5 5 15 кровотока данных м/секc функции обмен O 2, Как у Проницае Транс- Собира- Несут CO 2, капил- мы, важны порт ют венозную пит. вещест ляров для обмена венозной венозную кровь к вами крови кровь сердцу!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-21.jpg" alt="(!LANG:> STRUCTURAL AND FUNCTIONAL FEATURES OF ARTERIES 1. Arteries carry blood from the heart to authorities"> СТРУКТУРНО-ФУНКЦИОНАЛЬНЫЕ ОСОБЕННОСТИ АРТЕРИЙ 1. Артерии несут кровь от сердца к органам и тканям. 2. За исключением легочных и пупочных артерий, все они несут кровь, богатую кислородом. 3. По мере удаления от сердца они уменьшаются в диаметре и увеличиваются в количестве. 4. Артерии классифицируются по размере и преобладанию тканевых элементов в стенке на: v Эластического типа: аорта, !} pulmonary artery(these are large arteries). v Muscular-elastic (subclavian, common carotid artery, etc. - these are also large arteries) v Muscular type (ulnar, radial, renal, etc. - these are medium and small arteries). The arteries of the hybrid are also isolated.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-22.jpg" alt="(!LANG:> Aorta, Weigert stain, 162 x. Aortic wall contains 3"> Аорта, Окраска по Вейгерту, 162 x. Стенка аорты содержит 3 слоя: tunica intima (внутренний слой), tunica media (средний слой) и tunica adventitia (наружный слой), четкие границы между которыми отсутствуют.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-23.jpg" alt="(!LANG:> Aorta stained with Intima orcein"> Аорта, окраска орсеином Intima Elastica interna Media Adventitia Толщина стенка аорты в 10 раз меньше ее диаметра. Толщ интимы 150 мкм). Состоит из эндотелия, базальной мембраны и субэндотелиального слоя с коллагеновыми и эластическими волокнами и продольными пучками гладкомышечных клеток. Самая толстая оболочка – средняя (2 mm) , содержит окончатых эластических мембран. Адвентиция тонкая, содержит пучки коллагеновых волокон, немного эдастических волокон, кровеносных и лимфатических сосудов.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-24.jpg" alt="(!LANG:> The elastic membranes of the AORTA in the tunica media are called fenestrated, so"> Эластические мембраны АОРТА в tunica media называются фенестрированными, так как содержат отверстия (фенестры) облегчающие диффузию питательных веществ и продуктов распада. Соседние мембраны соединены эластическими волокнами (ЭВ). Обильная эластическая сеть в стенке аорты делает ее растяжимой и позволяет поддерживать постоянные кровоток не зависимо от сокращений сердца.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-25.jpg" alt="(!LANG:> axillary artery, staining according to Gomory - In mixed (muscular-elastic arteries) "> Axillary artery, staining according to Gomory - In mixed (muscular-elastic arteries) (external carotid, axillary) elastic and smooth muscle elements are mixed in the middle shell. - Hybrid include visceral branches of the abdominal aorta - in them, smooth muscle elements predominate in the inner parts of the media, and elestic ones - in the outer ones.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-26.jpg" alt="(!LANG:> ARTERIES: v Large arteries are called conductive because they"> АРТЕРИИ: v Крупные артерии называются проводящими, так как их основная функция – отводить кровь от сердца. v Крупные артерии выравнивают колебания кровяного давления, создаваемые ударами сердца. v Во время систолы эластические мембраны крупных артерий растягиваются и тем самым уменьшают давление, создаваемое выбросом крови. v Во время диастолы давление, создаваемое выбросом крови, резко падает, но эластические элементы крупных артерий сокращаются, выравнивая давление в кровеносном русле. v !} Arterial pressure decreases with distance from the heart, as does blood flow velocity. Pressure fluctuations between systole and diastole are leveled.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-27.jpg" alt="(!LANG:> Muscular type artery They can be large (like femoral, renal) and"> Артерия мышечного типа Они могут быть крупными (как бедренная, почечная) и мелкими, как безымянные внутриорганные артерии. Если функция артерий эластического типа заключается в проведении крови, то функция мышечных артерий – в распределении крови между органами. По мере необходимости они могут увеличиваться в размерах. Например, при закупорке основной артерии, мелкие коллатеральные артерии могут расшириться настолько, что полностью компенсируют недостаток!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-28.jpg" alt="(!LANG:>Tunica intima consists of an endothelial layer and a flattened muscular subendothelial artery"> Tunica intima состоит из слоя эндотелия и уплощенного Артерия мышечного субэндотелиального слоя из типа, x 132 коллагеновых и эластических волокон (последние могут отсутствовать в !} small arteries). To these two layers is added an internal elastic membrane (arrow) that separates the intima from the tunica media. Tunica media ™ is very thick and mainly consists of smooth muscle cells, forming 5-30 concentrically arranged layers of whorls. Among smooth muscle cells there may be thin reticular, collagen and elastic fibers, as well as amorphous intercellular substance. The outer elastic membrane (two arrows) is located between the tunica media and the adventitia and consists of several layers of elastic fibers.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-29.jpg" alt="(!LANG:> Muscle type artery under high magnification Adventitia sufficient"> Артерия мышечного типа под большим увеличением Адвентиция достаточно толстая, составляет ½ толщины tunica media. Она содержит эластические и коллагеновые волокна, немного фибробластов и адипоцитов. Лимфатические сосуды, vasa vasorum и нервы также обнаруживаются в адвентиции, они также могут проникать в наружную часть tunica media. В tunica media присутствуют прерывис- тые эластические мембраны (E).!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-30.jpg" alt="(!LANG:> Comparative characteristics of elastic and muscular arteries Elastic type"> Сравнительная характеристика артерий эластического и мышечного типа Эластический тип Мышечный тип Tunica intima: ширина~1/5 толщины Tunica intima тоньше в мышечных всей стенки, меньше эластических артериях, во многих местах элементов, чем в tunica media эндотелий лежит прямо на внутренней эластической мембране Tunica media: составляет основную толщу стенки В tunica media в основном эластические мембраны, гладкомышечные клетки; отдельные гладкомышечные относительно мало коллагеновых, клетки ретикулярных и эластических волокон Tunica adventitia относительно Adventitia толстая, примерно 1/3 тонкая, с коллагеновыми и или 2/3 толщины tunica media, эластическими волокнами содержит и эластические, и коллагеновые волокна!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-31.jpg" alt="(!LANG:> Veins 1. Return blood from the capillary bed to the heart. 2. Per"> Вены 1. Возвращают кровь от капиллярного русла к сердцу. 2. За исключением легочных и пупочных вен несут кровь, богатую углекислым газом. 3. Считаются емкостными сосудами, так как содержат одновременно свыше 70% общего объема крови.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-32.jpg" alt="(!LANG:> Muscular artery and accompanying vein"> Мышечная артерия и сопровождающая вена Поскольку давление и скорость кровотока в венах меньше, чем в артериях, они крупнее, чем артерии, но имеют более тонкие стенки. В основном структура стенки артерий и вен схожа, имеются те же 3 слоя: tunica intima , media & adventitia, хотя в венах они не столь резко vein artery отграничены. Просвет вен, в отличие от артерий, нередко спавшийся и в нем содержатся эритроциты.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-33.jpg" alt="(!LANG:> Muscular vein with strong development of muscular elements Valves"> Мышечная вена с сильным развитием мышечных элементов Клапаны появляются в венах, уже начиная с посткапиллярных венул, но особенно многочисленны они в венах с сильным развитием мышечных элементов – крупных венах нижних конечностей, несущих кровь против гравитации. Клапаны не встречаются в венах головного мозга, костного мозга, внутриорганных и полых венах. Безмышечные вены не содержат ГМК в стенке (вены трабекул селезенки, костей, мозговых оболочек: их стенки срастаются с окружающими тканями).!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-34.jpg" alt="(!LANG:> Comparative characteristics of muscular artery and vein Arteries do not contain valves!"> Сравнительная характеристика мышечной артерии и вены Артерии не содержат клапанов! 1. Просвет артерии уже, чем сопровождающей вены. 2. Стенка артерии более толстая и упругая, чем сопровождающей вены. 3. Артерии богаче эластические волокнами и ГМК, в то время как вены – коллагеновыми волокнами. 4. Самая толстая оболочка артерии – средняя, а вены – наружная. 5. Стенка вены более рыхлая, чем артерии. 6. Внутренняя эластическая мембрана лучше развита у артерии, чем у вены.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-35.jpg" alt="(!LANG:>The vein in the tunica media is thinner than in the"> Вена со В венах tunica media тоньше, чем в средним артериях, и составлена из циркулярно развитием расположенных гладкомышечных клеток, перемежающихся с элементов, соединительной тканью. H & E.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-36.jpg" alt="(!LANG:>Vena, with poor muscle development Some veins lack tunica media ( so-called"> Вена, со слабым развитием мышечных элементов Некоторые вены лишены tunica media (так называемый безмышечный тип): это вены селезенки, сетчатки глаза, костей, материнской части плаценты, а также большинство менингеальных и церебральных вен.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-37.jpg" alt="(!LANG:> Vein characteristics type TUNICA INTIMA TUNICA MEDIA TUNICA ADVENTITIA"> Характеристика вен тип TUNICA INTIMA TUNICA MEDIA TUNICA ADVENTITIA Крупные Эндотелий, базаль- Соединитель- Гладкомышечные клет- вены ная пластинка, в ная ткань, ки ориентированы некоторых – клапа- гладкомышеч- продольными пучками, ны, субэндотелиаль- ные клетки кардиомиоциты около ная соединительная впадения в сердце, слои ткань коллагеновых волокон с фибробластами Средние и Эндотелий, база- Ретикулярные Слои коллагеновых мелкие льная пластинка, в и эластиче- волокон с вены некоторых – кла- ские волокна, фибробластами паны, субэндотели- немного альная соедини- гладкомышеч тельная ткань ных клеток венулы Эндотелий, база- Скудная сое- Немного коллагеновых льная пластинка динительная волокон и мало (перициты в ткань с не- фибробластов посткапиллярных многими глад- венулах) комышечн. кл.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-38.jpg" alt="(!LANG:> Large vein - inferior vena cava"> Крупная вена – нижняя полая вена Диаметр крупных вен может превышать 1 см. Адвентиция составляет большая часть толщины стенки. В месте слияния с сердцем полые вены приобретают кардиомиоциты в своей адвентиции. В крупных венах сосуды сосудов достигают максимального развития – они могут проникать даже в!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-39.jpg" alt="(!LANG:>Superior vena cava, H & E. Tunica intima is represented by endothelium and subendothelial tissue."> Верхняя полая вена, H & E. Tunica intima представлена эндотелием и субэндотелиальной тканью. Tunica intima смешивается с tunica media , толщина которой резко редуцирована, в ней содержатся единичные гладкомышечные клетки и коллагеновые волокна. Сосуды в tunica adventitia составляют vasa vasorum , снабжающие !} vascular wall nutrients and oxygen, which do not get here from the lumen of the vessel. Adventitia: The inner layer contains thick tufts of CV in a spiral configuration - they shorten and lengthen along with the excursion of the diaphragm. The middle layer contains longitudinally oriented SMCs or cardiomyocytes. The outer layer contains thick bundles of CV intertwined with EV.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-40.jpg" alt="(!LANG:> The heart has three layers: HEART endocardium, myocardium and epicardium. Layers"> Сердце имеет три оболочки: HEART эндокард, миокард и эпикард. Слои эндокарда: v Эндотелий с базальной мембраной, v Субэндотелиальный слой (SL), - тонкий слой рыхлой соединительной ткани с немногочисленными фибро- бластами и тонкими КВ, v Миоэластический слой (ML), относительно плотная соединительная ткань с толстыми коллагеновыми и эластическими волокнами и вертикальными гладкомышеч- ными клетками, v Субэндокардиальный слой – рыхлая соединительная ткань, продолжающаяся в эндомизий миокарда. В области желудочков здесь содержатся волокна Пуркинье.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-41.jpg" alt="(!LANG:> Purkinje fibers, muscle fibers PAS response Myocardium –"> Волокна Пуркинье, ШИК-реакция muscle fibers Миокард – это самая толстая оболчка сердца, содержащая пучки сократительных мышечных волокон (типичные кардиомиоциты со спиральным ходом волокон) и видоизмененные несократительные мышечные волокна – волокна Пуркинье с субэндокардиальным расположением.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-42.jpg" alt="(!LANG:> Cardiomyocyte diagram Intercalated discs Cardiac"> Схема кардиомиоцита Вставочные диски Сердечная мышца, как и скелетная, является исчерченной, но в отличие от скелетной мышцы, в миокарде имеются клетки – кардиомиоциты, разделенные вставочными дисками, которые представляют собой соединительные комплексы на границе между соседними кардиомиоцитами.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-43.jpg" alt="(!LANG:> Intercellular junctions of cardiomyocytes The transverse part of the junction complex contains desmosomes"> Межклеточные соединения кардиомиоцитов Поперечная часть соединительного комплекса содержит десмосомы и нексусы (щелевые соединения), а продольная часть – длинные нексусы.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-44.jpg" alt="(!LANG:> Cardiomyocyte transverse striation Sarcomere structure in both cardiac and skeletal muscle"> Поперечная исчерченность кардиомиоцита Структура саркомера и в сердечной, и в скелетной мышце схожи – это заключенные между двумя Z- полосками две половинки изотропного диска и один анизотропный диск в центре саркомера, разделенный М-полоской пополам.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-45.jpg" alt="(!LANG:> Comparative characteristics of the sarcoplasmic reticulum and T-tubules in skeletal and cardiac muscle"> Сравнительная характеристика саркопламатического ретикулума и Т-трубочек в скелетной и сердечной мышце Скелетная сердечна я I диск T-трубочки Т-трубочка Z по- лоска Саркоплазма- тический Саркоплазма- ретикулум тический A диск ретикулум Терминальные диада цистерны Z-по- лоска Однако в миокарде Т-трубочки располагаются на уровне Z-полоски, а не между А- и I- дисками, как в скелетной мышце. Саркоплазматический ретикулум не столь развит, как в скелетной мышце, и терминальная цистерна хуже развита, уплощена, прерывиста и образует диаду, а не триаду, как в скелетной мышце, так как Т-трубочка связана только с одной терминальной цистерной (латеральным расширением саркоплазматического ретикулума).!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-46.jpg" alt="(!LANG:>Epicardial layers Heart v mesothelium (Mes), with"> Слои эпикарда Сердце v мезотелий (Mes), с базальной пластинкой (BL); v Субэпикардиальный слой (Sp. L), РСТ, богатая ЭВ, сосудами, НВ, адипоцитами вдоль коронарных сосудов. Сердце одето фибросерозным мешком - перикардом (P), состоящим из: v Мезотелия (Mes), с БМ, обращенного к эпикарду, и фиброзного слоя (FL), содержащего плотную CT с КС, ЛС, НВ.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-47.jpg" alt="(!LANG:> Cardiac conduction system Aorta Superior"> Проводящая система сердца Aorta Superior vena cava Левая ножка пучка Гиса Передний пучок Синоатриальный узел Атрио-вентрикуляр- ный узел Пучок Гиса Правая ножка пучка Гиса Задний пучок Волокна Пуркинье Это система видоизмененных кардиомиоцитов с функцией выработки и проведения импульсов !} heart contraction to different parts of the myocardium, as well as ensuring a rhythmic alternation of contraction of the ventricles and atria. Includes sinoatrial node, atrioventricular node, bundle of His (left and right leg) and Purkinje fibers.
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-48.jpg" alt="(!LANG:>Purkinje fibers, high magnification, H&E Action potential conduction velocity in atypical higher cardiomyocytes,"> Волокна Пуркинье, большое увеличение, H&E Скорость проведения потенциала действия у атипичных кардиомиоцитов выше, чем у типичных (3 -4 ms против to 0. 5 ms). Он вызывает вначале деполяризацию желудочков, а потом их сокращение.!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-49.jpg" alt="(!LANG:> Ultrastructure of Atypical Cardiomyocytes Cells"> Ультраструктура атипичных кардиомиоцитов Клетки Пуркинье Пейс-мейкерные Переходные!}
Src="https://present5.com/presentation/3/175135139_171487719.pdf-img/175135139_171487719.pdf-50.jpg" alt="(!LANG:> Comparative characteristics of atypical cardiomyocytes Feature Pacemaker Transient"> Сравнительная характеристика атипичных кардиомиоцитов Признак Пейс-мейкерные Переходные Клетки Пуркинье САУ, АВУ, место соединения между Субэндокардиальный Локализация Ссставляют САУ и АВУ типичными слой от пучка Гиса до кардиомиоцитами и верхушки сердца ВП Размер 10 x 25 mc Длиннее пейс- 50 x 100 mc мейкерных Ядро Круглое Удлиненное, часто 2 Цитоплазма Очень светлая Очень темная Менее плотная, чем у переходных клеток Митохондрии Немного крупных много мелких Много мелких Комплекс. Гольджи ++ Цистерны ГЭС + Миофибриллы + ++ Везикулы ++ + Гликоген +++ Базальная + пластинка вокруг всего волокна Межклеточные Zonulae adherentes Desmosomes, nexuses, соединения fasciae adherentes Генерируют импульс Функция сокращения, проводят его Проводят импульс к кардиомиоцитам и кардиомиоцитам переходным клеткам переходным клеткам!}
PRIVATE HISTOLOGY.
The cardiovascular system.
The system includes the heart, arterial and venous vessels, and lymphatic vessels. The system is laid at the 3rd week of embryogenesis. Vessels are laid from the mesenchyme. Vessels are classified according to diameter
Large
Medium
Small.
In the wall of the vessels, the inner, outer and middle shells are distinguished.
arteriesaccording to their structure, they are divided into
1. Elastic type arteries
2. Arteries of muscular-elastic (mixed) type.
3. Muscular arteries.
To elastic type arteries include large vessels such as the aorta and pulmonary artery. They have a thick developed wall.
ü Inner shell contains the endothelium layer, which is represented by flat endothelial cells on the basement membrane. It creates the conditions for blood flow. Next is the subendothelial layer of loose connective tissue. The next layer is a weaving of thin elastic fibers. blood vessels no. The inner membrane is nourished diffusely from the blood.
ü Middle shell powerful, wide, occupies the main volume. It contains thick elastic fenestrated membranes (40-50). They are built of elastic fibers and interconnected by the same fibers. They occupy the main volume of the membrane, separate smooth muscle cells are obliquely located in their windows. The structure of the vessel wall is determined by hemodynamic conditions, of which the most important are the speed of blood flow and the level of blood pressure. The wall of large vessels is well extensible, since the blood flow velocity (0.5-1 m/s) and pressure (150 mm Hg) are high here, so it returns well to its original state.
ü outer shell built of loose fibrous connective tissue, and it is denser in the inner layer of the outer shell. The outer and middle shells have their own vessels.
To musculo-elastic arteries include the subclavian and carotid arteries.
They have inner shell plexus of muscle fibers are replaced by an internal elastic membrane. This membrane is thicker than the fenestrated ones.
In the middle shell the number of fenestrated membranes decreases (by 50%), but the volume of smooth muscle cells increases, that is, the elastic properties decrease - the ability of the wall to stretch, but the contractility of the wall increases.
outer shell the same in structure as in large vessels.
Muscular type arteries prevail in the body among the arteries. They make up the bulk of the blood vessels.
Their inner shell corrugated, contains endothelium. The subendothelial layer of loose connective tissue is well developed. There is a strong elastic membrane.
Middle shell contains elastic fibers in the form of arcs, the ends of which are attached to the inner and outer elastic membranes. And their central departments like they're stuck. Elastic fibers and membranes form a single connected elastic frame, which occupies a small volume. In the loops of these fibers are bundles of smooth muscle cells. They sharply predominate and go circularly and in a spiral. That is, the contractility of the vessel wall increases. With the contraction of this shell, the section of the vessel is shortened, narrowed and twisted in a spiral.
outer shell contains an outer elastic membrane. It is not as tortuous and thinner than the inner one, but is also built of elastic fibers, and loose connective tissue is located along the periphery.
The smallest vessels of the muscular type are arterioles.
They retain three thinner shells.
In the inner shell contains an endothelium, a subendothelial layer, and a very thin internal elastic membrane.
In the middle shell smooth muscle cells are circular and spiral, and the cells are arranged in 1-2 rows.
In the outer shell there is no outer elastic membrane.
Arterioles break down into smaller hemocapillaries. They are located either in the form of loops or in the form of glomeruli, and most often form networks. The hemocapillaries are most densely located in intensively functioning organs and tissues - skeletal muscle fibers, cardiac muscle tissue. The diameter of the capillaries is not the same 4 to 7 µm. These are, for example, blood vessels in muscle tissue and brain substances. Their value corresponds to the diameter of the erythrocyte. Capillaries diameter 7-11 µm found in mucous membranes and skin. sinusoidal capillaries (20-30 microns) are present in hematopoietic organs and lacunar- in hollow organs.
The hemocapillary wall is very thin. Includes a basement membrane that regulates capillary permeability. The basement membrane splits in sections, and cells are located in the split areas pericytes. These are process cells, they regulate the lumen of the capillary. Inside the membrane are flat endothelial cells. Outside of the blood capillary lies loose, unformed connective tissue, it contains tissue basophils(mast cells) and adventitial cells that are involved in capillary regeneration. Hemocapillaries perform a transport function, but the leading one is trophic = exchange function. Oxygen easily passes through the walls of the capillaries into the surrounding tissues, and the metabolic products back. Implementation of the transport function helps slow blood flow, low blood pressure, a thin wall of the capillary and loose connective tissue located around.
The capillaries merge into venules . They begin the venous system of capillaries. Their wall has the same structure as that of the capillaries, but the diameter is several times larger. Arterioles, capillaries and venules make up the microcirculatory bed, which performs an exchange function and is located inside the organ.
Venules merge into veins. In the wall of the vein, 3 membranes are distinguished - internal, middle and external, but the veins differ in the content of smooth muscle elements of the connective tissue.
Allocate non-muscular type veins . They have only the inner shell, which contains the endothelium, subendothelial layer, connective tissue, which passes into the stroma of the organ. These veins are located in the dura mater, spleen, bones. They are easy to deposit blood.
Distinguish muscular type veins with underdeveloped muscle elements . They are located in the head, neck, torso. They have 3 shells. The inner layer contains the endothelium, the subendothelial layer. The middle shell is thin, poorly developed, contains separate circularly arranged bundles of smooth muscle cells. The outer shell consists of loose connective tissue.
Veins with moderately developed muscle elements located in the middle part of the body and in upper limbs. They have longitudinally located bundles of smooth muscle cells in the inner and outer shells. In the middle shell, the thickness of circularly located muscle cells increases.
Veins with highly developed muscular elements are located in the lower part of the body and in the lower extremities. In them, the inner shell forms folds-valves. In the inner and outer shells there are longitudinal bundles of smooth muscle cells, and the middle shell is represented by a continuous circular layer of smooth muscle cells.
In muscle-type veins, unlike arteries, the smooth inner surface has valves, there are no outer and inner elastic membranes, there are longitudinal bundles of smooth muscle cells, the middle membrane is thinner, smooth muscle cells are located in it circularly.
Regeneration.
Hemocapillaries regenerate very well. With an increase in the diameter of the vessels, the ability to regenerate deteriorates.
Histophysiology of the heart.
There are 3 membranes - endocardium, myocardium, pericardium. The endocardium develops from the mesenchyme, the myocardium from the mesoderm, the connective tissue plate of the epicardium from the mesenchyme, the mesothelium (pericardium) from the mesoderm. It is laid at the 4th week of embryogenesis.
Endocardium- relatively thin. Contains endothelium, subendothelial layer of loose connective tissue. The muscular-elastic layer is thin, it is formed by individual smooth muscle cells braided with elastic fibers. There is also an outer connective tissue layer. The endocardium is nourished diffusely.
The bulk of the wall is myocardium, which is represented by cardiac muscle tissue, a structural and functional unit, which are contractile cardiomyocytes. They form cardiac muscle fibers and due to processes-anastomoses they are connected with neighboring parallel muscle fibers and form a three-dimensional network of muscle fibers. Muscle fibers run in several directions. Between them are thin layers of loose connective tissue with a high density of hemocapillaries.
In the myocardium, on the border with the endocardium, there are fibers of the conduction system of the heart, which regulates the contractile activity of the myocardium. It is built from conducting cardiomyocytes.
The main mechanism of myocardial regeneration is intracellular regeneration, which leads to compensatory cell hypertrophy and compensation for the function of dead cardiomyocytes. In place of the dead cardiomyocytes, a connective tissue scar is formed.
epicardium. Its main component is a plate of loose connective tissue, which is covered with mesothelium from the surface. It secretes a mucous secretion. Due to this, there is a free sliding between the outer and inner sheets of the pericardium during contraction and relaxation of the heart muscle.
Lymphatic system.
Lymphatic vessels have the same structure as blood vessels, however, lymphatic capillaries have structural features. They begin blindly, they are wider than blood cells, and the basement membrane is more poorly developed in their wall. There are gaps between the endothelial cells, and loose connective tissue is located outside. Its tissue fluid, saturated with toxins, lipids and blood cells (mainly lymphocytes), penetrates through the slits into the lumen of the lymphatic capillaries and forms lymph, which then enters the bloodstream.
The main function is detoxification.
The blood system.
It includes blood and hematopoietic organs. They develop from the mesenchyme, which is formed at the 3rd week of embryogenesis mainly from the mesoderm, in a small amount from the ectoderm and is represented by process cells that are located between the germ layers. In embryogenesis, all types of connective tissue are formed from the mesenchyme, including blood, lymph, and smooth muscle tissue. After birth, there is no mesenchyme, it is transformed into derivatives, but they retain a large number of stem cells, that is, these tissues have a high ability to regenerate through cell proliferation and differentiation.
Functions blood .
1. Transport. Through the blood, respiratory, trophic, excretory functions are realized.
2. protective function.
3. Homeostatic function - maintaining the constancy of the body's environment.
Blood is a liquid tissue and an organ at the same time (5-6 liters). Its intercellular substance is liquid, has a special name - plasma. Plasma occupies 50-60% of the total blood volume. The rest is formed elements of the blood.
Plasma.Plasma is dominated by water (90-93%), the remaining 7-10% (the so-called dry residue) is represented by proteins (6-8.5%). These are fibrinogen, globulin, albumin.
Among the formed elements of blood, erythrocytes, leukocytes and platelets are distinguished.
red blood cellsdominate quantitatively. In men 4-5.5· 10 12 in a litre. For women 4-5· 10 12 per litre.
Erythrocytes are non-nucleated cells. 80% of the total number are discocytes, 20% are erythrocytes of a different shape (spiky, spherical). 75% of erythrocytes in diameter reach 7-8 microns. These are normocytes. Of the remaining 12.5% are microcytes, the remaining 12.5% are macrocytes.
Among erythrocytes there are reticulocytes. Their number is 2-12% . In their cytoplasm, they contain the remains of organelles in the form of a grid. An increase in the number of reticulocytes occurs when the red bone marrow is irritated.
RBCs lack organelles and contain hemoglobin, which has a high affinity for oxygen and carbon dioxide.
main function - transport = respiratory. They carry oxygen to the tissues and carbon dioxide in the opposite direction. On their surface, they transport antibodies, proteins, antigens, drugs.
Erythrocytes are formed in the red bone marrow, circulate and function in the blood (4 months), and die in the spleen.
Leukocytes(white blood cells). Their number is 4-9· 10 9 in a liter of blood. Leukocytes are divided into 2 groups.
1. Granular leukocytes or granulocytes. They contain a segmented nucleus, in the cytoplasm there is a specific granularity, which is perceived by different dyes. On this basis, leukocytes are divided into neutrophilic leukocytes, eosinophilic leukocytes and basophilic leukocytes.
2. Non-granular leukocytes or agranulocytes. These include lymphocytes, immune cells. They have no specific granularity in the cytoplasm, the nucleus is round, spherical in shape. They are mobile, able to pass through the wall of hemocapillaries, move in the tissues. Movement occurs according to the principle of chemotaxis.
The life cycle of all leukocytes contains phase of formation and maturation(in the organs of hematopoiesis). Then they go into the blood and circulate. This is a short term phase. AT tissue phase leukocytes enter the loose connective tissue, where they are activated and perform their functions and die there.
Granular leukocytes.
Neutrophilic leukocytes or neutrophils make up 50-75% of the total. Diameter 10-15 microns. To stain blood cells, azure-eosin or the so-called Romanovsky-Ginza method is used. In their cytoplasm, neutrophils contain fine, filamentous, abundant neutrophilic granularity. It contains bactericidal substances.
According to the degree of maturity and the structure of the nucleus, neutrophils are divided into segmented (45-70% of total). These are mature neutrophils. Their nucleus contains 3-4 segments connected by thin chromatin filaments. Functionally, they are microphages. They phagocytose toxic substances and microorganisms. Their phagocytic activity is 70-99%, and the phagocytic index is 12-25.
In addition to segmented, stab neutrophils are secreted - younger cells with S-shaped core.
Young neutrophils are also isolated. They make up 0-0.5%. These are functionally active cells, have a curved bean-shaped nucleus.
The number of neutrophils is expressed by the term neutrophilia. An increase in the number of mature forms is called a shift to the right, an increase in the number of young forms is a shift to the left. The number of neutrophils is increased in acute inflammatory diseases. Neutrophils are produced in the red bone marrow. The short period circulate in the blood is 2-3 hours. They pass to the surface of the epithelium. The tissue phase lasts 2-3 days.
Eosinophils . They are much smaller than neutrophils. Their number is 1-5% of the total. The diameter is 12-14 microns. The nucleus contains 2 large segments. The cytoplasm is filled with large eosinophilic granules and contains large acidophilic granules. The grains are lysosomes. Their content increases in allergic conditions, and they are able to phagocytize antigen-antibody complexes.
Basophilic granulocytes are 0-0.5%. Diameter 10-12 microns. They contain a large lobed nucleus, their cytoplasm contains large basophilic granules. These cells are formed in the red bone marrow and circulate in the blood for a short period. The tissue phase is long. It is assumed that tissue basophils-mast cells are formed from blood basophils, since their grains also contain heparin and histamine. The number of basophils in the blood increases with chronic diseases and is an unfavorable prognostic sign. Eosinophils are formed in the red bone marrow, and the functions are performed within 5-7 days in loose connective tissue.
non-granular leukocytes.
Lymphocytes make up 20-35% of all leukocytes. Among the lymphocytes, small lymphocytes predominate (diameter less than 7 µm). They have a rounded basophilic nucleus, a narrow basophilic rim of the cytoplasm, and poorly developed organelles. They also secrete medium lymphocytes (7-10 microns) and large lymphocytes (more than 10 microns) - they are not normally found in the blood, only with leukemia.
All lymphocytes according to immunological properties are divided into T-lymphocytes (60-70%), B-lymphocytes (20-30%) and null lymphocytes.
T-lymphocytesare thymus-dependent lymphocytes. They are formed in the thymus and, according to their properties, are divided into T-lymphocytes-killers(they provide cellular immunity). They recognize foreign cells, approach them, secrete cytotoxic substances that destroy the cytolemma of a foreign cell. Defects appear in the cytolemma, into which fluid rushes, the foreign cell is destroyed. Also allocate T-lymphocytes-helpers. They stimulate B-lymphocytes, turning them into plasma cells in response to an antigenic stimulus, their production of antibodies that neutralize antigens, they stimulate humoral immunity. Also allocate T-lymphocytes-suppressors. They suppress humoral immunity. Still allocate T-lymphocytes-amplifiers. They regulate relationships among all types of T-lymphocytes. Also allocate T-lymphocytes-memory. They remember information about the antigen at the first meeting and, when they meet again, provide a quick immune response. T-lymphocytes-memory determine stable immunity.
B-lymphocytesformed in the red bone marrow. The final differentiation occurs in the lymphatic nodules of the mucous membrane in the main alimentary canal. They provide humoral immunity. Upon receipt of the antigen, B-lymphocytes are transformed into plasma cells that produce antibodies (immunoglobulins) and the latter neutralize antigens. B-lymphocytes also include B-lymphocytes-memory. B-lymphocytes are relatively short-lived cells.
Memory T-lymphocytes and memory B-lymphocytes are recirculating cells. From the tissues they enter the lymph, from the lymph into the blood, from the blood into the tissue, then back into the lymph, and so on throughout their lives. When they encounter an antigen again, they undergo blast transformation, that is, they turn into lymphoblasts that proliferate and this leads to the rapid formation of effector lymphocytes, the action of which is directed to a specific antigen.
Null lymphocytes are lymphocytes that do not have the properties of either T-lymphocytes or B-lymphocytes. It is believed that blood stem cells, natural killers, circulate among them.
Monocytes are the largest cells, diameter 18-20 microns. They have a large bean-shaped sharply basophilic nucleus and a wide weakly basophilic cytoplasm. Organelles are moderately developed, of which lysosomes are better developed. Monocytes are produced in the red bone marrow. Up to several days, they circulate in the blood and in tissues and organs and turn into macrophages, which have a special name in each organ.