Types of blood vessels. Types, functions, structure of human blood vessels, vascular diseases The inner layer of blood vessels is called

Blood vessels are the most important part of the body, which is part of the circulatory system and permeates almost the entire human body. They are absent only in the skin, hair, nails, cartilage and cornea of ​​​​the eyes. And if they are assembled and stretched into one straight line, then the total length will be about 100 thousand km.

These tubular elastic formations function continuously, transferring blood from the constantly contracting heart to all corners of the human body, saturating them with oxygen and nourishing them, and then returning it back. By the way, the heart pushes more than 150 million liters of blood through the vessels in a lifetime.

The main types of blood vessels are: capillaries, arteries, and veins. Each type performs its specific functions. It is necessary to dwell on each of them in more detail.

Division into types and their characteristics

The classification of blood vessels is different. One of them involves division:

• on arteries and arterioles;
• precapillaries, capillaries, postcapillaries;
• veins and venules;
• arteriovenous anastomoses.

They represent a complex network, differing from each other in structure, size and their specific function, and form two closed systems connected to the heart - circles of blood circulation.

The following can be distinguished in the device: the walls of both arteries and veins have a three-layer structure:

• an inner layer that provides smoothness, built from the endothelium;
• medium, which is a guarantee of strength, consisting of muscle fibers, elastin and collagen;
• top layer of connective tissue.

Differences in the structure of their walls are only in the width of the middle layer and the predominance of either muscle fibers or elastic ones. And also in the fact that venous - contain valves.

arteries

They deliver blood saturated with useful substances and oxygen from the heart to all cells of the body. By structure, human arterial vessels are more durable than veins. Such a device (a denser and more durable middle layer) allows them to withstand the load of strong internal blood pressure.

The names of arteries, as well as veins, depend on:

Once upon a time it was believed that the arteries carry air and therefore the name is translated from Latin as “containing air”.

Feedback from our reader - Alina Mezentseva

I recently read an article that talks about the natural cream "Bee Spas Chestnut" for the treatment of varicose veins and cleaning blood vessels from blood clots. With the help of this cream, you can FOREVER cure VARICOSIS, eliminate pain, improve blood circulation, increase the tone of the veins, quickly restore the walls of blood vessels, clean and restore varicose veins at home.

I was not used to trusting any information, but I decided to check and ordered one package. I noticed the changes in a week: the pain went away, the legs stopped "buzzing" and swelling, and after 2 weeks the venous cones began to decrease. Try it and you, and if anyone is interested, then below is a link to the article.

There are such types:

Arteries, leaving the heart, become thinner to small arterioles. This is the name of the thin branches of the arteries, passing into the precapillaries, which form the capillaries.

These are the thinnest vessels, with a diameter much thinner than a human hair. This is the longest part of the circulatory system, and their total number in the human body ranges from 100 to 160 billion.

The density of their accumulation is different everywhere, but the highest in the brain and myocardium. They consist only of endothelial cells. They carry out a very important activity: the chemical exchange between the bloodstream and tissues.

For the treatment of VARICOSIS and cleaning blood vessels from blood clots, Elena Malysheva recommends a new method based on Cream of Varicose Veins cream. It contains 8 useful medicinal plants that are extremely effective in the treatment of VARICOSIS. In this case, only natural ingredients are used, no chemicals and hormones!

The capillaries are further connected to the post-capillaries, which become venules - small and thin venous vessels that flow into the veins.

Vienna

These are the blood vessels that carry oxygen-depleted blood back to the heart.

The walls of the veins are thinner than the walls of the arteries, because there is no strong pressure. The layer of smooth muscles in the middle wall of the vessels of the legs is most developed, because moving up is not an easy job for the blood under the action of gravity.

Venous vessels (all but the superior and inferior vena cava, pulmonary, collar, renal veins and veins of the head) contain special valves that ensure the movement of blood to the heart. The valves block the return flow. Without them, the blood would drain to the feet.

Arteriovenous anastomoses are branches of arteries and veins connected by fistulas.

Separation by functional load

There is another classification that blood vessels undergo. It is based on the difference in the functions they perform.

There are six groups:

There is another very interesting fact regarding this unique system of the human body. In the presence of excess weight in the body, more than 10 km (per 1 kg of fat) of additional blood vessels are created. All this creates a very large load on the heart muscle.

Heart disease and overweight, and even worse, obesity, are always very tightly linked. But the good thing is that the human body is also capable of the reverse process - the removal of unnecessary vessels while getting rid of excess fat (precisely from it, and not just from extra pounds).

What role do blood vessels play in human life? In general, they do a very serious and important job. They are a transport that ensures the delivery of essential substances and oxygen to every cell of the human body. They also remove carbon dioxide and waste from organs and tissues. Their importance cannot be overestimated.

DO YOU STILL THINK IT IS IMPOSSIBLE TO GET RID OF VARICOSIS!?

Have you ever tried to get rid of VARICOSIS? Judging by the fact that you are reading this article, the victory was not on your side. And of course, you know firsthand what it is:

• feeling of heaviness in the legs, tingling ...
• swelling of the legs, worse in the evening, swollen veins...
• bumps on the veins of the arms and legs ...

Now answer the question: does it suit you? Can ALL THESE SYMPTOMS be tolerated? And how much effort, money and time have you already "leaked" for ineffective treatment? After all, sooner or later the SITUATION WILL aggravate and the only way out will be only surgical intervention!

That's right - it's time to start ending this problem! Do you agree? That is why we decided to publish an exclusive interview with the head of the Institute of Phlebology of the Ministry of Health of the Russian Federation - V. M. Semenov, in which he revealed the secret of a penny method of treating varicose veins and complete restoration of blood vessels. Read interview...

Topic: Cardiovascular system. Blood vessels. General plan of the building. Varieties. Dependence of the vessel wall structure on hemodynamic conditions. arteries. Vienna. Classification. Structural features. Functions. Age features.

Cardiovascular system includes the heart, blood and lymph vessels. In this case, the heart, blood and lymphatic vessels are called the circulatory system or the circulatory system. Lymphatic vessels together with lymph nodes belong to the lymphatic system.

Circulatory system- This is a closed system of tubes of different calibers, which performs a transport, trophic, metabolic function and the function of regulating blood microcirculation in organs and tissues.

Vascular development

The source of the development of blood vessels is the mesenchyme. In the third week of embryonic development outside the body of the embryo in the wall of the yolk sac and in the chorion (in mammals), clusters of mesenchymal cells - blood islands - are formed. The peripheral cells of the islets form the walls of the vessels, and the centrally located mesenchymocytes differentiate into primary blood cells. Later, in the same way, the vessels appear in the body of the embryo and communication is established between the primary blood vessels of the extra-embryonic organs and the body of the embryo. Further development of the vascular wall and the acquisition of various structural features occurs under the influence of hemodynamic conditions, which include: blood pressure, the magnitude of its jumps, and blood flow velocity.

Vessel classification

Blood vessels are subdivided into arteries, veins, and vessels of the microvasculature, which include arterioles, capillaries, venules, and arteriolovenular anastomoses.

General plan of the structure of the wall of blood vessels

With the exception of capillaries and some veins, blood vessels have a general structural plan, they all consist of three shells:

Inner shell (intima) consists of two obligatory layers

Endothelium - a continuous layer of cells of a single-layer squamous epithelium, lying on the basement membrane and lining the inner surface of the vessel;

Subendothelial layer (subendothelium), formed by loose fibrous connective tissue.

Middle shell which usually contains smooth myocytes and the intercellular substance formed by these cells, represented by proteoglycans, glycoproteins, collagen and elastic fibers.

Outer sheath (adventitia) It is represented by loose fibrous connective tissue, with vascular vessels, lymphatic capillaries and nerves located in it.

arteries- these are vessels that ensure the movement of blood from the heart to the microcirculatory bed in organs and tissues. Arterial blood flows through the arteries, with the exception of the pulmonary and umbilical arteries.

Classification of arteries

According to the quantitative ratio of elastic and muscular elements in the vessel wall, the arteries are divided into:

Elastic arteries.

Arteries of mixed type (muscular-elastic) type.

Muscular arteries.

The structure of the elastic type arteries

These types of arteries include the aorta and the pulmonary artery. The wall of these vessels is subject to large pressure drops, so they require high elasticity.

1. Inner shell consists of three layers:

endothelial layer

The subendothelial layer, which has a significant thickness, because it absorbs pressure surges. Represented by loose fibrous connective tissue. In old age, cholesterol and fatty acids appear here.

The plexus of elastic fibers is a dense interlacing of longitudinally and circularly arranged elastic fibers.

2. Middle shell It is represented by 50-70 fenestrated elastic membranes, which look like cylinders inserted into each other, between which there are separate smooth myocytes, elastic and collagen fibers.

3. outer shell It is represented by loose fibrous connective tissue with blood vessels that feed the wall of the artery (vascular vessels) and nerves.

The structure of the arteries of the mixed (muscle-elastic) type

This type of artery includes the subclavian, carotid, and iliac arteries.

Three layers:

Endothelium

subendothelial layer

Internal elastic membrane

2. The middle shell consists of an approximately equal number of elastic elements (which include fibers and elastic membranes) and smooth myocytes.

3. The outer shell consists of loose connective tissue, where, along with vessels and nerves, there are longitudinally arranged bundles of smooth myocytes.

The structure of the arteries of the muscular type

These are all other arteries of medium and small caliber.

1. The inner shell consists of

endothelium

subendothelial layer

Internal elastic membrane

2. The middle shell has the greatest thickness, it is mainly represented by spirally arranged bundles of smooth muscle cells, between which collagen and elastic fibers are located.

Between the middle and outer shells of the artery is a weakly expressed outer elastic membrane.

3. The outer shell is represented by a loose fibrous connective tissue with vessels and nerves, there are no smooth myocytes.

Vienna are the vessels that carry blood to the heart. Venous blood flows through them, with the exception of the pulmonary and umbilical veins.

Due to the peculiarities of hemodynamics, which include lower blood pressure than in the arteries, the absence of sudden pressure drops, slow blood movement and lower oxygen content in the blood, veins have a number of structural features in their structure with arteries:

The veins are larger.

Their wall is thinner, easily collapses.

The elastic component and the subendothelial layer are poorly developed.

Weaker development of smooth muscle elements in the middle shell.

The outer shell is well defined.

The presence of valves, which are derivatives of the inner shell, the outside of the valve leaflets are covered with endothelium, their thickness is formed by loose fibrous connective tissue, and at the base there are smooth myocytes.

Vessels of vessels are contained in all shells of the vessel.

Vein classification

Muscleless veins.

2. Veins of the muscular type, which in turn are divided into:

Veins with poor myocyte development

Veins with medium myocyte development

Veins with strong myocyte development

The degree of development of myocytes depends on the localization of the vein: in the upper part of the body, the muscular component is poorly developed, in the lower part it is stronger.

The structure of a muscleless vein

Veins of this type are located in the brain, its membranes, retina, placenta, spleen, and bone tissue.

The vessel wall is formed by the endothelium, surrounded by loose fibrous connective tissue, tightly fuses with the stroma of the organs and therefore does not collapse.

The structure of veins with poor development of myocytes

These are the veins of the face, neck, upper body, and superior vena cava.

1. The inner shell consists of

endothelium

Weakly developed subendothelial layer

2. In the middle shell, there are poorly developed circularly arranged bundles of smooth muscle cells, between which there are a significant thickness of a layer of loose connective tissue.

3. The outer shell is represented by loose fibrous connective tissue.

The structure of the veins with the average development of myocytes

These include the brachial vein and the small veins of the body.

1. The inner shell consists of:

endothelium

subendothelial layer

2. The middle shell includes several layers of circularly arranged myocytes.

3. The outer shell is thick, contains longitudinally arranged bundles of smooth myocytes in loose fibrous connective tissue.

The structure of the veins with a strong development of myocytes

Such veins are located in the lower body and lower extremities. In addition to the good development of myocytes in all layers, the walls are characterized by the presence of valves that ensure the movement of blood towards the heart.

Regeneration of blood vessels

When the vessel wall is damaged, rapidly dividing endotheliocytes close the defect. The formation of smooth myocytes occurs slowly due to their division and differentiation of myoblasts and pericytes. With a complete rupture of medium and large vessels, their restoration without surgical intervention is impossible, but distal to the rupture, blood supply is restored due to collaterals and the formation of small vessels from protrusions of endotheliocytes in the walls of arterioles and venules.

Age features of blood vessels

The ratio between the diameter of arteries and veins at the time of the birth of a child is 1:1; in the elderly, these ratios change to 1:5. In a newborn, all blood vessels have thin walls, their muscle tissue and elastic fibers are poorly developed. In the first years of life in large vessels, the volume of the muscular membrane increases and the number of elastic and collagen fibers of the vascular wall increases. The intima and its subendothelial layer develop relatively quickly. The lumen of the vessels grows slowly. The complete formation of the wall of all blood vessels is completed by the age of 12. At the onset of 40 years of age, the reverse development of the arteries begins, while elastic fibers and smooth myocytes are destroyed in the arterial wall, collagen fibers grow, the subendothelium thickens sharply, the vessel wall thickens, salts are deposited in it, and sclerosis develops. Age-related changes in veins are similar, but appear earlier.

Blood vessels develop from the mesenchyme. First, the primary wall is laid, which later turns into the inner shell of the vessels. Mesenchyme cells, when combined, form a cavity of future vessels. The wall of the primary vessel consists of flat mesenchymal cells that form the inner layer of future vessels. This layer of flat cells belongs to the endothelium. Later, the final, more complex vessel wall is formed from the surrounding mesenchyme. It is characteristic that all vessels in the embryonic period are laid down and built as capillaries, and only in the process of their further development, a simple capillary wall is gradually surrounded by various structural elements, and the capillary vessel turns either into an artery, or into a vein, or into a lymphatic vessel.

The finally formed walls of the vessels of both arteries and veins are not the same throughout their entire length, but both of them consist of three main layers (Fig. 231). Common to all vessels is a thin inner shell, or intima (tunica intima), lined from the side of the vessel cavity with the thinnest, very elastic and flat polygonal endothelial cells. The intima is a direct continuation of the endothelium of the endocardium. This inner shell with a smooth and even surface prevents blood from clotting. If the endothelium of the vessel is damaged by a wound, infection, inflammatory or dystrophic process, etc., then small blood clots (clots - thrombi) form at the site of damage, which can increase in size and cause blockage of the vessel. Sometimes they break away from the place of formation, are carried away by the blood flow and, as so-called emboli, clog the vessel in some other place. The effect of such a thrombus or embolus depends on where the vessel is blocked. So, blockage of a vessel in the brain can cause paralysis; blockage of the coronary artery of the heart deprives the heart muscle of blood flow, which is expressed in a severe heart attack and often leads to death. Blockage of a vessel, suitable for any part of the body or internal organ, deprives it of nutrition and can lead to necrosis (gangrene) of the supplied part of the organ.

Outside of the inner layer is the middle shell (media), consisting of circular smooth muscle fibers with an admixture of elastic connective tissue.

The outer shell of the vessels (adventitia) envelops the middle one. It is built in all vessels from fibrous fibrous connective tissue, containing predominantly longitudinally located elastic fibers and connective tissue cells.

At the border of the middle and inner, middle and outer shells of the vessels, the elastic fibers form, as it were, a thin plate (membrana elastica interna, membrana elastica externa).

In the outer and middle shells of the blood vessels, the vessels that feed their wall (vasa vasorum) branch out.

The walls of capillary vessels are extremely thin (about 2 μ) and consist mainly of a layer of endothelial cells that form the capillary tube. This endothelial tube is externally braided with the thinnest network of fibers on which it is suspended, due to which it is very easy and without damage to be displaced. The fibers depart from a thin, main film, which is also associated with special cells - pericytes, covering the capillaries. The capillary wall is easily permeable to leukocytes and blood; it is at the level of capillaries through their wall that an exchange takes place between blood and tissue fluids, as well as between blood and the external environment (in the excretory organs).

Arteries and veins are usually divided into large, medium and small. The smallest arteries and veins that pass into the capillaries are called arterioles and venules. The wall of the arteriole consists of all three membranes. The innermost endothelial, and the middle one following it, is built from circularly arranged smooth muscle cells. When an arteriole passes into a capillary, only single smooth muscle cells are noted in its wall. With the enlargement of the same arteries, the number of muscle cells gradually increases to a continuous annular layer - arteries of the muscular type.

The structure of small and medium-sized arteries differs in some other feature. Directly under the inner endothelial membrane is a layer of elongated and stellate cells, which in larger arteries form a layer that plays the role of a cambium (growth layer) for the vessels. This layer is involved in the processes of regeneration of the vessel wall, i.e., it has the ability to restore the muscular and endothelial layers of the vessel. In arteries of medium caliber or mixed type, the cambial (growth) layer is more developed.

Arteries of large caliber (aorta, its large branches) are called arteries of the elastic type. Elastic elements predominate in their walls; in the middle shell, strong elastic membranes are concentrically laid, between which lies a significantly smaller number of smooth muscle cells. The cambial layer of cells, well expressed in small and medium-sized arteries, in large arteries turns into a layer of subendothelial loose connective tissue rich in cells.

Due to the elasticity of the walls of the artery, like rubber tubes, under the pressure of blood, they can easily stretch and do not collapse, even if the blood is released from them. All the elastic elements of the vessels together form a single elastic skeleton, working like a spring, each time returning the vessel wall to its original state, as soon as smooth muscle fibers relax. Since arteries, especially large ones, have to withstand fairly high blood pressure, their walls are very strong. Observations and experiments show that the arterial walls can withstand even such strong pressure as occurs in the steam boiler of an ordinary steam locomotive (15 atm.).

The walls of veins are usually thinner than the walls of arteries, especially their medial sheath. There is also much less elastic tissue in the venous wall, so the veins collapse very easily. The outer shell is built of fibrous connective tissue, in which collagen fibers predominate.

A feature of the veins is the presence of valves in them in the form of semi-lunar pockets (Fig. 232), formed from the doubling of the inner shell (intima). However, valves are not found in all veins in our body; they are deprived of the veins of the brain and its membranes, the veins of the bones, as well as a significant part of the veins of the viscera. Valves are more common in the veins of the limbs and neck, they are open towards the heart, i.e., in the direction of blood flow. By blocking the backflow that can occur due to low blood pressure and due to the law of gravity (hydrostatic pressure), the valves facilitate the flow of blood.

If there were no valves in the veins, the entire weight of a column of blood more than 1 m high would press on the blood entering the lower limb and this would greatly impede blood circulation. Further, if the veins were rigid tubes, the valves alone would not be able to circulate the blood, since the entire column of fluid would still press on the underlying sections. The veins are located among the large skeletal muscles, which, contracting and relaxing, periodically compress the venous vessels. When the contracting muscle compresses the vein, the valves below the pinch close and those above open; when the muscle relaxes and the vein is again free from compression, the upper valves in it close and retain the upstream column of blood, while the lower ones open and allow the vessel to refill with blood coming from below. This pumping action of the muscles (or "muscle pump") greatly aids the circulation of the blood; standing for many hours in one place, in which the muscles do little to help the movement of blood, is more tiring than walking.

Blood vessels - elastic tubes through which blood is transported to all organs and tissues, and then again collected to the heart. The study of blood vessels, along with lymphatics, is dealt with by the section of medicine - angiology. Blood vessels form: a) the macrocirculatory bed - these are the arteries and veins through which blood moves from the heart to the organs and returns to the heart; b) microcirculatory bed - includes capillaries, arterioles and venules located in organs that provide the exchange of substances between blood and tissues.

arteries - blood vessels that carry blood from the heart to organs and tissues. The walls of arteries have three layers:

outer layer built of loose connective tissue, it contains nerves that regulate the expansion and narrowing of blood vessels;

middle layer comprises smooth muscle membrane and elastic fibers(due to the contraction or relaxation of the muscles, the lumen of the vessels can change, regulating the flow of blood, and the elastic fibers give the vessels elasticity)

the inner layer - It is formed by a special connective tissue, the cells of which have very smooth membranes that do not interfere with the movement of blood.

Depending on the diameter of the arteries, the structure of the wall also changes in them, therefore, three types of arteries are distinguished: elastic (for example, aorta, pulmonary trunk), muscular (organ arteries) and mixed, or muscular-elastic (for example, carotid artery) type.

capillaries- the smallest blood vessels that connect arteries and veins and provide exchange of substances between blood and tissue fluid. Their diameter is about 1 micron, the total surface of all body capillaries is 6300 m2. The walls consist of a single layer of flat epithelial cells - the endothelium. The endothelium is the inner layer of flat, elongated cells with uneven, wavy edges that line the capillaries, as well as all other vessels and the heart. Endotheliocytes produce a number of physiologically active substances. Among them, nitric oxide causes relaxation of smooth myocytes, thereby causing vasodilation. In organs, capillaries provide blood microcirculation and form a network, but they can also form loops (for example, in the papillae of the skin), as well as glomeruli (for example, in the nephrons of the kidneys). Different organs have different levels of development of the capillary network. For example, there are 40 capillaries per 1 mm2 in the skin, and about 1000 in the muscles. The gray matter of the central nervous system organs, endocrine glands, skeletal muscles, heart, and adipose tissue have a significant development of the capillary network.

Vienna- blood vessels that carry blood from organs and tissues to the heart. They have the same wall structure as the arteries, but thin and less elastic. The medium and some large veins have semilunar valves that allow blood to flow in only one direction. The veins are muscular (hollow) and bezmyazovi (retina, bones). The movement of blood through the veins to the heart is facilitated by the suction action of the heart, stretching of the vena cava in the chest cavity when air is inhaled, and the presence of a valve apparatus.

Comparative characteristics of vessels

Functional classification of blood vessels.

main vessels.

resistive vessels.

exchange vessels.

capacitive vessels.

shunt vessels.

Main vessels - aorta, large arteries. The wall of these vessels contains many elastic elements and many smooth muscle fibers. Meaning: Turn the pulsating ejection of blood from the heart into a continuous blood flow.

Resistive vessels - pre- and post-capillary. Precapillary vessels - small arteries and arterioles, capillary sphincters - vessels have several layers of smooth muscle cells. Postcapillary vessels - small veins, venules - also have smooth muscles. Meaning: Provide the greatest resistance to blood flow. Precapillary vessels regulate blood flow in the microvasculature and maintain a certain amount of blood pressure in large arteries. Postcapillary vessels - maintain a certain level of blood flow and pressure in the capillaries.

Exchange vessels - 1 layer of endothelial cells in the wall - high permeability. They carry out transcapillary exchange.

Capacitive vessels - all venous. They contain 2/3 of all blood. They have the least resistance to blood flow, their wall is easily stretched. Meaning: due to expansion, they deposit blood.

Shunt vessels - connect arteries with veins bypassing the capillaries. Meaning: provide unloading of the capillary bed.

The number of anastomoses is not a constant value. They occur when blood circulation is disturbed or there is a lack of blood supply.

Sensitivity - there are many receptors in all layers of the vessel wall. With a change in pressure, volume, chemical composition of blood - receptors are excited. Nerve impulses go to the central nervous system and reflexively affect the heart, blood vessels, and internal organs. Due to the presence of receptors, the vascular system is connected with other organs and tissues of the body.

Mobility - the ability of blood vessels to change the lumen in accordance with the needs of the body. The change in the lumen occurs due to the smooth muscles of the vascular wall.

Vascular smooth muscles have the ability to spontaneously generate nerve impulses. Even at rest there is a moderate tension of the vascular wall - basal tone. Under the influence of factors, smooth muscles either contract or relax, changing the blood supply.

Meaning:

regulation of a certain level of blood flow,

ensuring constant pressure, redistribution of blood;

capacitance of blood vessels is adjusted to the volume of blood

Circulation time - the time during which the cow passes both circles of blood circulation. With a heart rate of 70 per minute, the time is 20 - 23 s, of which 1/5 of the time is for a small circle; 4/5 time - for a big circle. Time is determined using control substances and isotopes. - they are injected intravenously into the v.venaris of the right hand and it is determined after how many seconds this substance will appear in the v.venaris of the left hand. Time is affected by volumetric and linear velocities.

Volumetric velocity - the volume of blood that flows through the vessels per unit time. Vlin. - the speed of movement of any particle of blood in the vessels. The highest linear velocity in the aorta, the smallest - in the capillaries (respectively 0.5 m/s and 0.5 mm/s). The linear velocity depends on the total cross-sectional area of ​​the vessels. Due to the low linear velocity in the capillaries, the conditions for transcapillary exchange. This speed in the center of the vessel is greater than at the periphery.

The movement of blood is subject to physical and physiological laws. Physical: - laws of hydrodynamics.

1st law: the amount of blood flowing through the vessels and the speed of its movement depends on the pressure difference at the beginning and end of the vessel. The greater this difference, the better the blood supply.

2nd law: the movement of blood is hindered by peripheral resistance.

Physiological patterns of blood flow through the vessels:

work of the heart;

closedness of the cardiovascular system;

suction action of the chest;

vascular elasticity.

In the systole phase, blood enters the vessels. The vessel wall is stretched. There is no ejection of blood in diastole, the elastic vascular wall returns to its original state, and energy accumulates in the wall. With a decrease in the elasticity of blood vessels, a pulsating blood flow appears (normally in the vessels of the pulmonary circulation). In pathological sclerotically altered vessels - Musset's symptom - head movements in accordance with pulsation.