Blood flows through the veins of the pulmonary circulation. Pulmonary circulation

This is the continuous movement of blood through a closed cardiovascular system, ensuring the exchange of gases in the lungs and body tissues.

In addition to providing tissues and organs with oxygen and removing carbon dioxide from them, blood circulation delivers to the cells nutrients, water, salts, vitamins, hormones and removes metabolic end products, and also maintains a constant body temperature, ensures humoral regulation and the interconnection of organs and organ systems in the body.

The circulatory system consists of the heart and blood vessels that penetrate all organs and tissues of the body.

Blood circulation begins in the tissues where metabolism occurs through the walls of the capillaries. The blood, which has given oxygen to the organs and tissues, enters the right half of the heart and is sent by it to the pulmonary circulation, where the blood is saturated with oxygen, returns to the heart, entering its left half, and is again distributed throughout the body (systemic circulation) .

Heart- the main organ of the circulatory system. It is a hollow muscular organ, consisting of four chambers: two atria (right and left), separated interatrial septum, and two ventricles (right and left), separated interventricular septum. The right atrium communicates with the right ventricle through the tricuspid, and the left atrium communicates with the left ventricle through bicuspid valve. The average weight of an adult human heart is about 250 g in women and about 330 g in men. Heart length 10-15 cm, cross dimension 8-11 cm and anteroposterior - 6-8.5 cm. The heart volume in men is on average 700-900 cm 3, and in women - 500-600 cm 3.

The outer walls of the heart are formed by cardiac muscle, which is similar in structure to striated muscles. However, the heart muscle is distinguished by its ability to contract rhythmically automatically due to impulses arising in the heart itself, regardless of external influences(automatic heart).

The function of the heart is to rhythmically pump blood into the arteries, which comes to it through the veins. The heart beats about 70-75 times per minute when the body is at rest (1 time per 0.8 s). More than half of this time it rests - relaxes. The continuous activity of the heart consists of cycles, each of which consists of contraction (systole) and relaxation (diastole).

There are three phases of cardiac activity:

contraction of the atria - atrial systole - takes 0.1 s
contraction of the ventricles - ventricular systole - takes 0.3 s
general pause - diastole (simultaneous relaxation of the atria and ventricles) - takes 0.4 s

Thus, during the entire cycle, the atria work for 0.1 s and rest for 0.7 s, the ventricles work for 0.3 s and rest for 0.5 s. This explains the ability of the heart muscle to work without getting tired throughout life. The high performance of the heart muscle is due to increased blood supply to the heart. Approximately 10% of the blood ejected by the left ventricle into the aorta enters the arteries that branch from it, which supply the heart.

Arteries- blood vessels that carry oxygenated blood from the heart to organs and tissues (only the pulmonary artery carries venous blood).

The artery wall is represented by three layers: the outer connective tissue membrane; middle, consisting of elastic fibers and smooth muscles; internal, formed by endothelium and connective tissue.

In humans, the diameter of the arteries ranges from 0.4 to 2.5 cm. The total volume of blood in the arterial system averages 950 ml. The arteries gradually branch into smaller and smaller vessels - arterioles, which turn into capillaries.

Capillaries(from the Latin “capillus” - hair) - the smallest vessels (average diameter does not exceed 0.005 mm, or 5 microns), penetrating the organs and tissues of animals and humans that have a closed circulatory system. They connect small arteries - arterioles with small veins - venules. Through the walls of capillaries, consisting of endothelial cells, gases and other substances are exchanged between the blood and various tissues.

Vienna- blood vessels carrying saturated carbon dioxide, metabolic products, hormones and other substances, blood from tissues and organs to the heart (with the exception of the pulmonary veins, which carry arterial blood). The wall of a vein is much thinner and more elastic than the wall of an artery. Small and medium-sized veins are equipped with valves that prevent blood from flowing back into these vessels. In humans, the volume of blood in the venous system averages 3200 ml.

Circulation circles

The movement of blood through vessels was first described in 1628 by the English physician W. Harvey.

In humans and mammals, blood moves through a closed cardiovascular system, consisting of the systemic and pulmonary circulation (Fig.).

The large circle starts from the left ventricle, carries blood throughout the body through the aorta, gives oxygen to tissues in the capillaries, takes up carbon dioxide, turns from arterial to venous and returns to the vena cava through the superior and inferior vena cava. right atrium.

The pulmonary circulation begins from the right ventricle, through pulmonary artery carries blood to the pulmonary capillaries. Here the blood releases carbon dioxide, is saturated with oxygen and flows through the pulmonary veins to the left atrium. From the left atrium, through the left ventricle, blood again enters the systemic circulation.

Pulmonary circulation- pulmonary circle - serves to enrich the blood with oxygen in the lungs. It starts from the right ventricle and ends at the left atrium.

From the right ventricle of the heart deoxygenated blood enters the pulmonary trunk (common pulmonary artery), which soon divides into two branches - blood bearers to the right and left lung.

In the lungs, arteries branch into capillaries. In the capillary networks that weave around the pulmonary vesicles, the blood gives up carbon dioxide and receives in return a new supply of oxygen (pulmonary respiration). Blood saturated with oxygen acquires a scarlet color, becomes arterial and flows from the capillaries into the veins, which, merging into four pulmonary veins (two on each side), flow into the left atrium of the heart. The pulmonary circulation ends in the left atrium, and arterial blood entering the atrium passes through the left atrioventricular opening into the left ventricle, where the systemic circulation begins. Consequently, venous blood flows in the arteries of the pulmonary circulation, and arterial blood flows in its veins.

Systemic circulation- bodily - collects venous blood from the upper and lower half of the body and similarly distributes arterial blood; starts from the left ventricle and ends at the right atrium.

From the left ventricle of the heart, blood flows into the largest arterial vessel - the aorta. Arterial blood contains the nutrients and oxygen necessary for the body to function and is bright scarlet in color.

The aorta branches into arteries that go to all organs and tissues of the body and pass through them into arterioles and then into capillaries. The capillaries, in turn, gather into venules and then into veins. Through the capillary wall, metabolism and gas exchange occurs between the blood and body tissues. Arterial blood flowing in the capillaries gives off nutrients and oxygen and in return receives metabolic products and carbon dioxide (tissue respiration). As a result, the blood entering the venous bed is poor in oxygen and rich in carbon dioxide and therefore has a dark color - venous blood; When bleeding, you can determine by the color of the blood which vessel is damaged - an artery or a vein. The veins merge into two large trunks - the superior and inferior vena cava, which flow into the right atrium of the heart. This section of the heart ends the systemic (bodily) circulation.

The complement to the great circle is third (cardiac) circle of blood circulation, serving the heart itself. It begins with the coronary arteries of the heart emerging from the aorta and ends with the veins of the heart. The latter merge into the coronary sinus, which flows into the right atrium, and the remaining veins open directly into the atrium cavity.

Movement of blood through vessels

Any liquid flows from a place where the pressure is higher to where it is lower. The greater the pressure difference, the higher the flow speed. Blood in the vessels of the systemic and pulmonary circulation also moves due to the pressure difference created by the heart through its contractions.

In the left ventricle and aorta, blood pressure is higher than in the vena cava (negative pressure) and in the right atrium. The pressure difference in these areas ensures the movement of blood in the systemic circulation. High pressure in the right ventricle and pulmonary artery and low pressure in the pulmonary veins and left atrium ensure the movement of blood in the pulmonary circulation.

The most high pressure in the aorta and large arteries (blood pressure). Blood pressure is not constant [show]

Blood pressure- this is the pressure of blood on the walls of the blood vessels and chambers of the heart, resulting from the contraction of the heart, pumping blood into the vascular system, and vascular resistance. The most important medical and physiological indicator of the state of the circulatory system is the pressure in the aorta and large arteries - blood pressure.

Arterial blood pressure is not a constant value. U healthy people at rest, the maximum, or systolic, blood pressure is distinguished - the level of pressure in the arteries during heart systole is about 120 mmHg, and the minimum, or diastolic, is the level of pressure in the arteries during diastole of the heart is about 80 mmHg. Those. arterial blood pressure pulsates in time with the contractions of the heart: at the moment of systole it rises to 120-130 mm Hg. Art., and during diastole it decreases to 80-90 mm Hg. Art. These pulse pressure fluctuations occur simultaneously with pulse fluctuations of the arterial wall.

As blood moves through the arteries, part of the pressure energy is used to overcome the friction of the blood against the walls of the vessels, so the pressure gradually drops. A particularly significant drop in pressure occurs in the smallest arteries and capillaries - they offer the greatest resistance to blood movement. In the veins, blood pressure continues to gradually decrease, and in the vena cava it is equal to atmospheric pressure or even below it. Blood circulation indicators in different parts of the circulatory system are given in Table. 1.

The speed of blood movement depends not only on the pressure difference, but also on the width of the bloodstream. Although the aorta is the widest vessel, it is the only one in the body and all the blood flows through it, which is pushed out by the left ventricle. Therefore, the maximum speed here is 500 mm/s (see Table 1). As the arteries branch, their diameter decreases, but the total cross-sectional area of all arteries increases and the speed of blood movement decreases, reaching 0.5 mm/s in the capillaries. Due to such a low speed of blood flow in the capillaries, the blood has time to give oxygen and nutrients to the tissues and accept their waste products.

The slowdown in blood flow in the capillaries is explained by their huge number (about 40 billion) and large total lumen (800 times larger than the lumen of the aorta). The movement of blood in the capillaries is carried out due to changes in the lumen of the supplying small arteries: their expansion increases blood flow in the capillaries, and narrowing decreases it.

The veins on the way from the capillaries, as they approach the heart, enlarge, merge, their number and total lumen bloodstream decreases, and the speed of blood movement compared to capillaries increases. From the table 1 also shows that 3/4 of all blood is in the veins. This is due to the fact that thin walls veins can easily stretch, so they can contain significantly more blood than the corresponding arteries.

The main reason for the movement of blood through the veins is the pressure difference at the beginning and end of the venous system, so the movement of blood through the veins occurs in the direction of the heart. This is facilitated by the suction action chest(“respiratory pump”) and contraction of skeletal muscles (“muscle pump”). During inhalation, the pressure in the chest decreases. In this case, the pressure difference at the beginning and end of the venous system increases, and blood through the veins is directed to the heart. Skeletal muscles contract and compress the veins, which also helps move blood to the heart.

The relationship between the speed of blood movement, the width of the bloodstream and blood pressure is illustrated in Fig. 3. The amount of blood flowing per unit time through the vessels is equal to the product of the speed of blood movement and the cross-sectional area of the vessels. This value is the same for all parts of the circulatory system: the amount of blood the heart pushes into the aorta, the same amount flows through the arteries, capillaries and veins, and the same amount returns back to the heart, and is equal to the minute volume of blood.

Redistribution of blood in the body

If the artery extending from the aorta to some organ expands due to the relaxation of its smooth muscles, then the organ will receive more blood. At the same time, other organs will receive less blood due to this. This is how blood is redistributed in the body. Due to redistribution, more blood flows to working organs at the expense of organs that are currently at rest.

The redistribution of blood is regulated by the nervous system: simultaneously with the dilation of blood vessels in working organs, the blood vessels of non-working organs narrow and blood pressure remains unchanged. But if all the arteries dilate, this will lead to a drop in blood pressure and a decrease in the speed of blood movement in the vessels.

Blood circulation time

Blood circulation time is the time required for blood to pass through the entire circulation. A number of methods are used to measure blood circulation time [show]

The principle of measuring the time of blood circulation is that a substance that is not usually found in the body is injected into a vein, and it is determined after what period of time it appears in the vein of the same name on the other side or causes its characteristic effect. For example, a solution of the alkaloid lobeline, which acts through the blood on the respiratory center of the medulla oblongata, is injected into the cubital vein, and the time from the moment of administration of the substance to the moment when a short-term breath holding or cough appears is determined. This occurs when lobeline molecules, having circulated in the circulatory system, affect the respiratory center and cause a change in breathing or cough.

In recent years, the rate of blood circulation in both circles of blood circulation (or only in the small, or only in the large circle) is determined using a radioactive sodium isotope and an electron counter. To do this, several such counters are placed on different parts bodies near large vessels and in the heart area. After introducing a radioactive sodium isotope into the cubital vein, the time of appearance of radioactive radiation in the area of the heart and the vessels under study is determined.

The blood circulation time in humans is on average approximately 27 heart systoles. At 70-80 heart beats per minute, complete blood circulation occurs in approximately 20-23 seconds. We must not forget, however, that the speed of blood flow along the axis of the vessel is greater than at its walls, and also that not all vascular areas have the same length. Therefore, not all blood circulates so quickly, and the time indicated above is the shortest.

Studies on dogs have shown that 1/5 of the time of complete blood circulation is in the pulmonary circulation and 4/5 in the systemic circulation.

Regulation of blood circulation

Innervation of the heart. The heart, like other internal organs, is innervated by the autonomic nervous system and receives double innervation. Sympathetic nerves approach the heart, which strengthen and accelerate its contractions. The second group of nerves - parasympathetic - acts on the heart in the opposite way: it slows down and weakens heart contractions. These nerves regulate the functioning of the heart.

In addition, the functioning of the heart is influenced by the adrenal hormone - adrenaline, which enters the heart with the blood and increases its contractions. The regulation of organ function with the help of substances carried by the blood is called humoral.

The nervous and humoral regulation of the heart in the body act in concert and ensure precise adaptation of the activity of the cardiovascular system to the needs of the body and environmental conditions.

Innervation of blood vessels. Blood vessels are supplied by sympathetic nerves. Excitation spreading through them causes contraction of smooth muscles in the walls of blood vessels and narrows the blood vessels. If you cut the sympathetic nerves going to a certain part of the body, the corresponding vessels will dilate. Consequently, excitation constantly flows through the sympathetic nerves to the blood vessels, which keeps these vessels in a state of certain constriction - vascular tone. When the excitation increases, the frequency nerve impulses increases and the vessels narrow more strongly - vascular tone increases. On the contrary, when the frequency of nerve impulses decreases due to inhibition of sympathetic neurons, vascular tone decreases and blood vessels dilate. To the vessels of some organs (skeletal muscles, salivary glands) in addition to vasoconstrictors, vasodilator nerves are also suitable. These nerves are stimulated and dilate the blood vessels of the organs as they work. The lumen of blood vessels is also affected by substances carried by the blood. Adrenaline constricts blood vessels. Another substance, acetylcholine, secreted by the endings of some nerves, dilates them.

Regulation of the cardiovascular system. The blood supply to organs changes depending on their needs due to the described redistribution of blood. But this redistribution can only be effective if the pressure in the arteries does not change. One of the main functions nervous regulation blood circulation is to maintain constant blood pressure. This function is carried out reflexively.

There are receptors in the wall of the aorta and carotid arteries that become more irritated if blood pressure exceeds normal level. Excitation from these receptors goes to the vasomotor center located in the medulla oblongata and inhibits its work. From the center along the sympathetic nerves to the vessels and heart, weaker excitation begins to flow than before, and the blood vessels dilate, and the heart weakens its work. Due to these changes, blood pressure decreases. And if the pressure for some reason drops below normal, then the irritation of the receptors stops completely and the vasomotor center, without receiving inhibitory influences from the receptors, increases its activity: it sends more nerve impulses per second to the heart and blood vessels, the vessels narrow, the heart contracts more often and stronger, blood pressure rises.

Cardiac hygiene

Normal activity human body is possible only if you have a well-developed cardiovascular system. The speed of blood flow will determine the degree of blood supply to organs and tissues and the rate of removal of waste products. During physical work, the organs' need for oxygen increases simultaneously with the intensification and acceleration of heart contractions. Only a strong heart muscle can provide such work. To be resilient to diversity labor activity, it is important to train the heart, increase the strength of its muscles.

Physical labor and physical education develop the heart muscle. To provide normal function cardiovascular system, a person should start his day with morning exercises, especially people whose professions are not related to physical labor. To enrich the blood with oxygen physical exercise It's best to do it outdoors.

It must be remembered that excessive physical and mental stress can cause disruption of the normal functioning of the heart and heart disease. Especially bad influence Alcohol, nicotine, and drugs affect the cardiovascular system. Alcohol and nicotine poison the heart muscle and nervous system, causing sudden violations regulation of vascular tone and cardiac activity. They lead to development serious illnesses cardiovascular system and can cause sudden death. Young people who smoke and drink alcohol are more likely than others to experience heart spasms, which can cause severe heart attacks and sometimes death.

First aid for wounds and bleeding

Injuries are often accompanied by bleeding. There are capillary, venous and arterial bleeding.

Capillary bleeding occurs even with a minor injury and is accompanied by a slow flow of blood from the wound. Such a wound should be treated with a solution of brilliant green (brilliant green) for disinfection and apply a clean gauze bandage. The bandage stops bleeding, promotes the formation of a blood clot and prevents germs from entering the wound.

Venous bleeding is characterized by a significantly higher rate of blood flow. The blood that flows out is dark in color. To stop bleeding, it is necessary to apply a tight bandage below the wound, that is, further from the heart. After the bleeding stops, the wound is treated disinfectant (3% peroxide solution hydrogen, vodka), bandage with a sterile pressure bandage.

During arterial bleeding, scarlet blood gushes from the wound. This is the most dangerous bleeding. If an artery in a limb is damaged, you need to raise the limb as high as possible, bend it and press the wounded artery with your finger in the place where it comes close to the surface of the body. It is also necessary above the wound site, that is, closer to the heart, to apply a rubber tourniquet (you can use a bandage or rope for this) and tighten it tightly to completely stop the bleeding. The tourniquet should not be kept tight for more than 2 hours. When applying it, you must attach a note in which you should indicate the time of application of the tourniquet.

It should be remembered that venous, and even more so, arterial bleeding can lead to significant blood loss and even death. Therefore, if injured, it is necessary to stop the bleeding as soon as possible, and then take the victim to the hospital. Strong pain or fear can cause a person to lose consciousness. Loss of consciousness (fainting) is a consequence of inhibition of the vasomotor center, a drop in blood pressure and insufficient blood supply to the brain. The person who has lost consciousness should be given some non-toxic substance to smell. strong odor substance (for example ammonia), wet your face cold water or lightly pat his cheeks. When olfactory or skin receptors are irritated, excitation from them enters the brain and relieves inhibition of the vasomotor center. Blood pressure rises, the brain receives adequate nutrition, and consciousness returns.

In the human body, there are two circles of blood circulation: large (systemic) and small (pulmonary). The systemic circle originates in the left ventricle and ends in the right atrium. Arteries great circle blood circulation carries out metabolism, carries oxygen and nutrition. In turn, the arteries of the pulmonary circulation enrich the blood with oxygen. Metabolic products are removed through the veins.

Arteries of the systemic circulation moves blood from the left ventricle first through the aorta, then through the arteries to all organs of the body, and this circle ends in the right atrium. The main purpose of this system is to deliver oxygen and nutrients to the organs and tissues of the body. Metabolic products are removed through veins and capillaries. The main function of the pulmonary circulation is the process of gas exchange in the lungs.

Arterial blood, which moves through the arteries, having passed its path, passes into the venous. After most of the oxygen has been given away and carbon dioxide has passed from the tissues into the blood, it becomes venous. All small vessels (venules) are collected in large veins systemic circulation. They are the superior and inferior vena cava.

They flow into the right atrium, and here the systemic circulation ends.

Ascending aorta

Blood from the left ventricle begins its circulation. First it enters the aorta. This is the most significant vessel of the large circle.

It is divided into:

ascending part
aortic arch,
descending part.

This is the largest cardiac vessel has many branches - arteries, through which blood flows to most internal organs.

These are the liver, kidneys, stomach, intestines, brain, skeletal muscles etc.

The carotid arteries send blood to the head, vertebral arteries – to the upper limbs. Then the aorta passes down along the spine, and here it enters the lower limbs and organs abdominal cavity and torso muscles.

In the aorta - highest blood flow speed.

At rest it is 20-30 cm/s, and at physical activity increases by 4-5 times. Arterial blood is rich in oxygen, it passes through the vessels and enriches all organs, and then through the veins, carbon dioxide and cellular metabolic products again enter the heart, then into the lungs and, passing through the pulmonary circulation, are removed from the body.

Location of the ascending aorta in the body:

begins with an extension, the so-called onion;
exits the left ventricle at the level of the third intercostal space on the left;
goes up and behind the sternum;
at the level of the second costal cartilage it passes into the aortic arch.

The length of the ascending aorta is about 6 cm.

They are moving away from her right and left coronary arteries which supply blood to the heart.

Aortic arch

Three large vessels depart from the aortic arch:

brachiocephalic trunk;
left common carotid artery;
left subclavian artery.

They bleed enters top part torso, head, neck, upper limbs.

Starting from the second costal cartilage, the aortic arch turns left and back to the fourth thoracic vertebra and passes into the descending aorta.

This is the longest part of this vessel, which is divided into thoracic and abdominal sections.

Brachiocephalic trunk

One of the large vessels, 4 cm long, goes up and to the right from the right sternal-clavicular joint. This vessel is located deep in the tissues and has two branches:

right common carotid artery;
right subclavian artery.

They supply blood to the organs of the upper body.

Descending aorta

The descending aorta is divided into a thoracic (up to the diaphragm) and an abdominal (below the diaphragm) part. It is located in front of the spine, starting from the 3rd-4th thoracic vertebra to the level of the 4th lumbar vertebra. This is the longest part of the aorta; at the lumbar vertebra it is divided into:

right iliac artery,
left iliac artery.

k.), and along the veins - venous (v. k.), but in the small circle the opposite happens: v. It enters from the heart into the lungs through the pulmonary arteries, releases carbon dioxide to the outside, is enriched with oxygen, becomes arterial, and returns from the lungs through the pulmonary veins.

How does venous blood differ from arterial blood? A.K. is saturated with O 2 and nutrients; it flows from the heart to organs and tissues. V. k. - “spent”, it gives O 2 and nutrition to the cells, takes CO 2 and metabolic products from them and returns from the periphery back to the heart.

Human venous blood differs from arterial blood in color, composition and functions.

By color

A.K. has a bright red or scarlet tint. This color is given to it by hemoglobin, which added O 2 and became oxyhemoglobin. V.K. contains CO 2, so its color is dark red, with a bluish tint.

By composition

In addition to gases, oxygen and carbon dioxide, the blood also contains other elements. In a. k. a lot of nutrients, and c. to. - mainly metabolic products, which are then processed by the liver and kidneys and excreted from the body. The pH level also differs: in a. k. it is higher (7.4) than that of v. k. (7.35).

By movement

Blood circulation in arterial and venous systems significantly different. A. k. moves from the heart to the periphery, and v. k. - in the opposite direction. When the heart contracts, blood is ejected from it under a pressure of approximately 120 mmHg. pillar As it passes through the capillary system, its pressure decreases significantly and is approximately 10 mmHg. pillar Thus, a. k. moves under pressure from high speed, and c. It flows slowly under low pressure, overcoming the force of gravity, and its reverse flow is prevented by valves.

How the transformation of venous blood into arterial blood and vice versa occurs can be understood if we consider the movement in the pulmonary and systemic circulation.

Blood saturated with CO 2 enters the lungs through the pulmonary artery, from where CO 2 is excreted. Then saturation with O 2 occurs, and the blood already enriched with it enters the heart through the pulmonary veins. This is how movement occurs in the pulmonary circulation. After this, the blood makes a large circle: a. It carries oxygen and nutrition through the arteries to the cells of the body. Giving up O 2 and nutrients, it is saturated with carbon dioxide and metabolic products, becomes venous and returns through the veins to the heart. This completes the large circle of blood circulation.

By functions performed

The veins carry out the outflow of blood, which has taken away cell waste products and CO 2 . In addition, it contains nutrients that are absorbed digestive organs, and produced by glands internal secretion hormones.

By bleeding

Due to the characteristics of movement, bleeding will also differ. At arterial blood is in full swing, such bleeding is dangerous and requires prompt first aid and medical attention. With venous flow, it calmly flows out in a stream and can stop on its own.

Other differences

A.K. is located on the left side of the heart, in. k. – in the right, blood mixing does not occur.
Venous blood, unlike arterial blood, is warmer.
V. k. flows closer to the surface of the skin.
A.K. in some places comes close to the surface and here the pulse can be measured.
The veins through which the v. flows. to., much more than arteries, and their walls are thinner.
Movement a.k. is ensured by a sharp release during contraction of the heart, outflow into the. the valve system helps.
The use of veins and arteries in medicine is also different - they inject medications, it is from this that biological fluid is taken for analysis.

Instead of a conclusion

Main differences a. k. and v. consist in the fact that the first is bright red, the second is burgundy, the first is saturated with oxygen, the second is saturated with carbon dioxide, the first moves from the heart to the organs, the second - from the organs to the heart.

Blood circulation in humans

Arterial blood is blood saturated with oxygen.

Venous blood is saturated with carbon dioxide.

Arteries are vessels that carry blood away from the heart.

Veins are vessels that carry blood to the heart.

(In the pulmonary circulation, venous blood flows through the arteries, and arterial blood flows through the veins.)

In humans, in all other mammals, as well as in birds, the heart has a four-chamber, consists of two atria and two ventricles (in the left half of the heart there is arterial blood, in the right - venous, mixing does not occur due to a complete septum in the ventricle).

Between the ventricles and atria there are leaflet valves, and between the arteries and ventricles there are semilunar valves. The valves prevent blood from flowing backwards (from the ventricle to the atrium, from the aorta to the ventricle).

The thickest wall is at the left ventricle, because it pushes blood through the systemic circulation. When the left ventricle contracts, a pulse wave is created, as well as maximum blood pressure.

Systemic circulation: from the left ventricle, arterial blood flows through the arteries to all organs of the body. In the capillaries of the large circle, gas exchange occurs: oxygen passes from the blood into the tissues, and carbon dioxide passes from the tissues into the blood. The blood becomes venous, flows through the vena cava into the right atrium, and from there into the right ventricle.

Small circle: from the right ventricle, venous blood flows through the pulmonary arteries to the lungs. Gas exchange occurs in the capillaries of the lungs: carbon dioxide passes from the blood into the air, and oxygen from the air into the blood, the blood becomes arterial and flows through the pulmonary veins into the left atrium, and from there into the left ventricle.

ASSIGNMENTS ON THIS TOPIC: Heart

Tests and assignments

Establish a correspondence between the sections of the circulatory system and the circle of blood circulation to which they belong: 1) Systemic circulation, 2) Pulmonary circulation. Write numbers 1 and 2 in the correct order.

A) Right ventricle

B) Carotid artery

B) Pulmonary artery

D) Superior vena cava

D) Left atrium

E) Left ventricle

Choose three correct answers out of six and write down the numbers under which they are indicated. Large circle of blood circulation in the human body

1) begins in the left ventricle

2) originates in the right ventricle

3) is saturated with oxygen in the alveoli of the lungs

4) supplies organs and tissues with oxygen and nutrients

5) ends in the right atrium

6) brings blood to left half hearts

1. Establish the sequence of human blood vessels in order of decreasing blood pressure in them. Write down the corresponding sequence of numbers.

1) inferior vena cava

3) pulmonary capillaries

4) pulmonary artery

2. Establish the order in which the blood vessels should be arranged in order of decreasing blood pressure in them

Establish a correspondence between the vessels and human circulatory circles: 1) pulmonary circulation, 2) systemic circulation. Write numbers 1 and 2 in the correct order.

B) pulmonary veins

B) carotid arteries

D) capillaries in the lungs

D) pulmonary arteries

E) hepatic artery

Choose one, the most correct option. Why can't blood get from the aorta to the left ventricle of the heart?

1) the ventricle contracts with great strength and creates high pressure

2) semilunar valves fill with blood and close tightly

3) leaflet valves are pressed against the walls of the aorta

4) leaflet valves are closed and semilunar valves are open

Choose one, the most correct option. Blood enters the pulmonary circulation from the right ventricle through

1) pulmonary veins

2) pulmonary arteries

3) carotid arteries

Choose one, the most correct option. Arterial blood flows through the human body

1) renal veins

2) pulmonary veins

4) pulmonary arteries

Choose one, the most correct option. In mammals, blood is enriched with oxygen in

1) arteries of the pulmonary circulation

2) capillaries of the great circle

3) arteries of the great circle

4) capillaries of the small circle

1. Establish the sequence of blood movement through the vessels of the systemic circulation. Write down the corresponding sequence of numbers.

1) portal vein of the liver

3) gastric artery

4) left ventricle

5) right atrium

6) inferior vena cava

2. Define correct sequence blood circulation in the systemic circulation, starting from the left ventricle. Write down the corresponding sequence of numbers.

2) Superior and inferior vena cava

3) Right atrium

4) Left ventricle

5) Right ventricle

6) Tissue fluid

3. Establish the correct sequence of blood passage through the systemic circulation. Write down the corresponding sequence of numbers in the table.

1) right atrium

2) left ventricle

3) arteries of the head, limbs and torso

5) inferior and superior vena cava

4. Establish the sequence of blood movement in the human body, starting with the left ventricle. Write down the corresponding sequence of numbers.

1) left ventricle

4) pulmonary veins

5) right atrium

Arrange the blood vessels in order of decreasing speed of blood movement in them

1) superior vena cava

3) brachial artery

Choose one, the most correct option. The vena cava in the human body drains into

1) left atrium

2) right ventricle

3) left ventricle

4) right atrium

Choose one, the most correct option. Valves prevent blood from flowing back from the pulmonary artery and aorta into the ventricles.

1. Establish the sequence of blood movement in a person through the pulmonary circulation. Write down the corresponding sequence of numbers.

1) pulmonary artery

2) right ventricle

4) left atrium

2. Establish the sequence of circulatory processes, starting from the moment when blood moves from the lungs to the heart. Write down the corresponding sequence of numbers.

1) blood from the right ventricle enters the pulmonary artery

2) blood moves through the pulmonary vein

3) blood moves through the pulmonary artery

4) oxygen comes from the alveoli to the capillaries

5) blood enters the left atrium

6) blood enters the right atrium

3. Establish the sequence of movement of arterial blood in a person, starting from the moment it is saturated with oxygen in the capillaries of the pulmonary circle. Write down the corresponding sequence of numbers.

1) left ventricle

2) left atrium

3) veins of the small circle

4) small circle capillaries

5) arteries of the great circle

4. Establish the sequence of movement of arterial blood in the human body, starting with the capillaries of the lungs. Write down the corresponding sequence of numbers.

1) left atrium

2) left ventricle

4) pulmonary veins

5) capillaries of the lungs

Establish the sequence of events that occur in the cardiac cycle after blood enters the heart. Write down the corresponding sequence of numbers.

1) contraction of the ventricles

2) general relaxation of the ventricles and atria

3) blood flow into the aorta and artery

4) blood flow into the ventricles

5) atrial contraction

Establish a correspondence between human blood vessels and the direction of blood movement in them: 1) from the heart, 2) to the heart

A) veins of the pulmonary circulation

B) veins of the systemic circulation

B) arteries of the pulmonary circulation

D) arteries of the systemic circulation

Choose three options. A person has blood from the left ventricle of the heart

1) when it contracts, it enters the aorta

2) when it contracts, it enters the left atrium

3) supplies body cells with oxygen

4) enters the pulmonary artery

5) under high pressure enters the greater circulation

6) under slight pressure enters the pulmonary circulation

Choose three options. Blood flows through the arteries of the pulmonary circulation in humans

4) oxygenated

5) faster than in the pulmonary capillaries

6) slower than in the pulmonary capillaries

Choose three options. Veins are blood vessels through which blood flows

3) under greater pressure than in the arteries

4) under less pressure than in the arteries

5) faster than in capillaries

6) slower than in capillaries

Choose three options. Blood flows through the arteries of the systemic circulation in humans

3) saturated with carbon dioxide

4) oxygenated

5) faster than in other blood vessels

6) slower than in other blood vessels

1. Establish a correspondence between the type of human blood vessels and the type of blood they contain: 1) arterial, 2) venous

A) pulmonary arteries

B) veins of the pulmonary circulation

B) aorta and arteries of the systemic circulation

D) superior and inferior vena cava

2. Establish a correspondence between a vessel of the human circulatory system and the type of blood that flows through it: 1) arterial, 2) venous. Write numbers 1 and 2 in the order corresponding to the letters.

A) femoral vein

B) brachial artery

B) pulmonary vein

D) subclavian artery

D) pulmonary artery

Choose three options. In mammals and humans, venous blood, unlike arterial,

1) poor in oxygen

2) flows in a small circle through the veins

3) fills the right half of the heart

4) saturated with carbon dioxide

5) enters the left atrium

6) provides body cells with nutrients

Analyze the table “The work of the human heart.” For each cell indicated by a letter, select the corresponding term from the list provided.

2) Superior vena cava

4) Left atrium

5) Carotid artery

6) Right ventricle

7) Inferior vena cava

8) Pulmonary vein

Choose three correct answers out of six and write down the numbers under which they are indicated. Elements of the human circulatory system containing venous blood are

1) pulmonary artery

4) right atrium and right ventricle

5) left atrium and left ventricle

6) pulmonary veins

Choose three correct answers out of six and write down the numbers under which they are indicated. Blood leaks from the right ventricle

5) towards the lungs

6) towards the cells of the body

Establish a correspondence between the processes and the circles of blood circulation for which they are characteristic: 1) small, 2) large. Write numbers 1 and 2 in the order corresponding to the letters.

A) Arterial blood flows through the veins.

B) The circle ends in the left atrium.

B) Arterial blood flows through the arteries.

D) The circle begins in the left ventricle.

D) Gas exchange occurs in the capillaries of the alveoli.

E) Venous blood is formed from arterial blood.

Find three errors in the given text. Indicate the numbers of the proposals in which they are made. (1) The walls of arteries and veins have a three-layer structure. (2) The walls of the arteries are very elastic and resilient; The walls of the veins, on the contrary, are inelastic. (3) When the atria contract, blood is pushed into the aorta and pulmonary artery. (4) The blood pressure in the aorta and vena cava is the same. (5) The speed of blood movement in the vessels is not the same; in the aorta it is maximum. (6) The speed of blood movement in capillaries is higher than in veins. (7) Blood in the human body moves through two circulation circles.

Circulatory system. Circulation circles

Question 1. What kind of blood flows through the arteries of the systemic circle, and what kind of blood flows through the arteries of the small circle?

Arterial blood flows through the arteries of the systemic circle, and venous blood flows through the arteries of the small circle.

Question 2. Where does the systemic circulation begin and end, and where does the pulmonary circulation end?

All vessels form two circles of blood circulation: large and small. The great circle begins in the left ventricle. The aorta departs from it, which forms an arch. Arteries arise from the aortic arch. From the initial part of the aorta they extend coronary vessels, which supply blood to the myocardium. The part of the aorta located in the chest is called the thoracic aorta, and the part located in the abdominal cavity is called the abdominal aorta. The aorta branches into arteries, arteries into arterioles, and arterioles into capillaries. From the capillaries of a large circle, oxygen and nutrients flow to all organs and tissues, and carbon dioxide and metabolic products flow from the cells into the capillaries. Blood turns from arterial to venous.

Cleansing the blood from poisonous products disintegration occurs in the vessels of the liver and kidneys. Blood from digestive tract, pancreas and spleen enters portal vein liver. In the liver, the portal vein branches into capillaries, which then unite again into the common trunk of the hepatic vein. This vein drains into the inferior vena cava. Thus, all blood from the abdominal organs, before entering the systemic circle, passes through two capillary networks: through the capillaries of these organs themselves and through the capillaries of the liver. The portal system of the liver ensures the neutralization of toxic substances that are formed in the large intestine. The kidneys also have two capillary networks: the network of the renal glomeruli, through which the blood plasma containing harmful products metabolism (urea, uric acid), passes into the cavity of the nephron capsule, and capillary network, entwining convoluted tubules.

Capillaries merge into venules, then into veins. Then, all the blood flows into the superior and inferior vena cava, which flow into the right atrium.

The pulmonary circulation begins in the right ventricle and ends in the left atrium. Venous blood from the right ventricle enters the pulmonary artery, then into the lungs. Gas exchange occurs in the lungs, venous blood turns into arterial blood. The four pulmonary veins carry arterial blood to the left atrium.

Question 3. To a closed or open system refers to the lymphatic system?

The lymphatic system should be classified as open. It blindly begins in the tissues with lymphatic capillaries, which then unite to form lymphatic vessels, which in turn form lymphatic ducts that empty into the venous system.

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Circulation circles | Paragraph 21

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Which vein carries arterial blood?

In principle, arterial blood does not flow through the veins! It (as the name suggests) flows through the arteries! Arteries run deeper than veins. Arterial pressure always higher than venous, since main artery(aorta) comes from the heart, which pumps blood into it under pressure. The aorta is divided into smaller arteries, which in turn also branch, and so on, right up to the capillaries that carry oxygen to every cell of the body. This is how the cells “inhale”. Arterial blood is scarlet, saturated with oxygen.

Venous blood flows through the veins; it carries waste (exhalation) from each cell “to be released.” The veins are located closer to the surface, the pressure in them is less (here the heart creates not pressure, but “discharge”), the blood is dark.

I don't agree with the answer above. Everything that is written there is completely applicable to the systemic circulation. And in the pulmonary circulation, it is through the pulmonary veins that arterial blood flows from the lungs to the left atrium.

Arterial blood is the blood that flows through the arteries, and venous blood is the blood that flows through the veins.

This is one of the most common misconceptions.

It arose due to the consonance of words in the pairs “artery - arterial” and “vein - venous” (blood) and due to ignorance of these terms.

Firstly, the vessels are divided into arteries and veins depending on where they carry blood.

Arteries are efferent vessels, and blood flows through them from the heart to the organs.

Veins are afferent vessels; they carry blood from the organs to the heart.

Thirdly, the conclusion from these differences is the question: “Can arterial blood flow through the veins, and venous blood through the arteries?” and the seemingly paradoxical answer to it: “Maybe!” In the pulmonary circulation, in which the blood is saturated with oxygen in the lungs, this is exactly what happens.

Blood saturated with carbon dioxide (venous) flows from the heart to the lungs through the efferent vessels (arteries). Conversely, from the lungs to the heart, oxygen-rich blood (arterial) enters the heart through the afferent vessels (veins). In a large circle, which “serves” all the organs of the body and distributes oxygen, arterial (“oxygen”) blood runs through the arteries (from the heart), and venous (“carbon dioxide”) blood flows back through the veins (to the heart).

In medicine, blood is usually divided into arterial and venous. It would be logical to think that the first flows in the arteries, and the second in the veins, but this is not entirely true. The fact is that in the systemic circulation, arterial blood (a.k.) actually flows through the arteries, and venous blood (v.k.) through the veins, but in the small circle the opposite happens: c. It enters from the heart into the lungs through the pulmonary arteries, releases carbon dioxide to the outside, is enriched with oxygen, becomes arterial, and returns from the lungs through the pulmonary veins.

Human venous blood differs from arterial blood in color, composition and functions.

By color

A.K. has a bright red or scarlet tint. This color is given to it by hemoglobin, which added O 2 and became oxyhemoglobin. V.K. contains CO 2, so its color is dark red, with a bluish tint.

By composition

By movement

Blood circulation in the arterial and venous systems is significantly different. A. k. moves from the heart to the periphery, and v. k. - in the opposite direction. When the heart contracts, blood is ejected from it under a pressure of approximately 120 mmHg. pillar As it passes through the capillary system, its pressure decreases significantly and is approximately 10 mmHg. pillar Thus, a. k. moves under pressure at high speed, and c. It flows slowly under low pressure, overcoming the force of gravity, and its reverse flow is prevented by valves.

How the transformation of venous blood into arterial blood and vice versa occurs can be understood if we consider the movement in the pulmonary and systemic circulation.

By functions performed

Main function a. k. – transfer of nutrition and oxygen to cells through the arteries of the systemic circulation and the veins of the small circulation. Passing through all organs, it gives off O 2, gradually takes up carbon dioxide and turns into venous.

The veins carry out the outflow of blood, which has taken away cell waste products and CO 2 . In addition, it contains nutrients that are absorbed by the digestive organs and hormones produced by the endocrine glands.

By bleeding

Due to the characteristics of movement, bleeding will also differ. With arterial bleeding, the blood flows in full swing; such bleeding is dangerous and requires prompt first aid and medical attention. With venous flow, it calmly flows out in a stream and can stop on its own.

Other differences

A.K. is located on the left side of the heart, in. k. – in the right, blood mixing does not occur.
Venous blood, unlike arterial blood, is warmer.
V. k. flows closer to the surface of the skin.
A.K. in some places comes close to the surface and here the pulse can be measured.
The veins through which the v. flows. to., much more than arteries, and their walls are thinner.
Movement a.k. is ensured by a sharp release during contraction of the heart, outflow into the. the valve system helps.
The use of veins and arteries in medicine also differs - medications are injected into the vein, and it is from it that biological fluid is taken for analysis.

Instead of a conclusion

Arteries of the systemic circulation.

1. Abdominal aorta 9. Middle adrenal artery

2. Right and left common iliac arteries 10. Left kidney

3. Diaphragm 11. Left renal artery

4. Inferior phrenic arteries 12. Left ureter.

5. Adrenal gland 13. Testicular artery, right and left

6. Superior adrenal artery 14. Median sacral artery

7. Lumbar arteries 15. Esophagus

Aorta- the largest arterial vessel in the human body, originating from the left ventricle. All the arteries that form the systemic circulation depart from the aorta. The aorta is divided into the ascending aorta, arch and descending aorta (Fig. 10, 11).

Ascending aorta is a continuation of the left ventricle, goes upward, reaching the level of the second rib, where it continues and passes into the aortic arch. The right and left aorta depart from the ascending aorta coronary arteries- arteries of the heart (Fig. 10).

Aortic arch. Three large vessels depart from the aortic arch: the brachiocephalic trunk, the left common carotid artery and the left subclavian artery (Fig. 10).

Brachiocephalic trunk departs from the initial aortic arch and represents large vessel 4 cm long, which goes up and to the right and at the level of the right sternoclavicular joint is divided into two branches: the right common carotid artery and the right subclavian artery.

Due to the brachiocephalic trunk, left common carotid artery, left subclavian artery blood supply to the neck, head, and upper limbs.

Descending aorta is a continuation of the aortic arch and begins at the level tel III- IV thoracic vertebra to the level of the IV lumbar vertebra, where it gives off the right and left common iliac arteries (Fig. 10, 11).

At the level of the XII thoracic vertebra, the descending aorta passes through the hilum of the diaphragm, descending into the abdominal cavity. Up to the diaphragm, the descending aorta is called the thoracic aorta, and below the diaphragm is called the abdominal aorta.

Thoracic aorta is located directly on the spinal column and is upper section the descending aorta, which is located in the chest cavity (Fig. 10). From thoracic aorta There are two types of branches: visceral branches (to the internal organs) and parietal branches (to the muscle layers).

I. Internal branches:

1. Bronchial branches - two, less often three or four, enter the gates of the lungs and branch together with the bronchi, heading to the bronchial lymph nodes, pericardial sac, plecum, esophagus (Fig. 10).

3. Mediastinal branches - supply blood connective tissue and mediastinal lymph nodes.

4. Branches of the pericardial sac - directed to the posterior surface of the pericardial sac.

II. Parietal branches.

1. The superior phrenic arteries, two in number, depart from the aorta and
heading to top surface diaphragm.

2. Posterior intercostal arteries begin on the posterior surface of the thoracic aorta on
along its entire length and go to the sternum. Nine of them lie in
intercostal spaces from the third to the eleventh inclusive. The most
the lower ones go under the XII rib and are called subcostal arteries (Fig. 10).

Abdominal aorta is a continuation of the thoracic aorta, begins at the level of the XII thoracic vertebra and reaches the IV-V lumbar vertebra, where it divides into two common iliac arteries. Two types of branches also depart from the abdominal aorta: parietal and splanchnic branches (Fig. 11).

I. Parietal branches

1. The inferior phrenic artery supplies blood to the diaphragm. A thin branch is separated from the inferior phrenic artery, supplying blood to the adrenal gland - the superior adrenal artery (Fig. 11).

2. Lumbar arteries - 4 paired arteries arising from the abdominal aorta at the level of the bodies of the I-IV lumbar vertebrae, directed towards the anterior abdominal wall, rectus abdominis muscles (Fig. 11).

II. Internal branches.

1. The celiac trunk is a short vessel 1-2 cm long, which departs from the anterior surface of the aorta at the level of the XII thoracic vertebra and immediately divides into 3 branches: the left gastric artery, the common hepatic artery, the splenic artery (Fig. 11, 12). Thanks to these three vessels and their branches, the arterial blood supply to the stomach, pancreas, spleen, liver, and gall bladder occurs.

2.3. Upper mesenteric artery. Inferior mesenteric artery.

They depart from the anterior surface of the abdominal aorta, go through the peritoneum, supplying blood to the large and small intestines (Fig. 13, 14).

4. The middle adrenal artery supplies blood to the adrenal gland (Fig. 11).

5. The renal artery is a paired large artery. It begins at the level of the II lumbar vertebra and goes to the kidney (Fig. 11). Each renal artery gives off a small inferior adrenal artery to the adrenal gland.

6. Testicular (ovarian) artery. It arises from the abdominal aorta below the renal artery. Supplies blood to the male (female) genital organs (Fig. 11).

Median sacral artery is a direct continuation of the abdominal aorta, represents thin vessel, passing from top to bottom in the middle of the pelvic surface of the sacrum and ends at the coccyx (Fig. 11).

Figure 14. Inferior mesenteric artery Figure 15. Azygos and semi-gypsy veins.

1. Inferior mesenteric artery 1. Superior vena cava

2. Inferior mesenteric vein 2. Right brachiocephalic vein

3. Abdominal aorta 3. Left brachiocephalic vein

4. Right general iliac artery 4. Azygos vein

5. Transverse colon (large) 5. Hemizygos vein

6. Descending colon (large) 6. Lumbar veins

7. Sigmoid colon(thick) 7. Ascending lumbar veins

9. Bladder 9. Bronchi

10. Inferior vena cava 10. Posterior intercostal veins

11. Accessory hemizygos vein

12. Right subclavian vein

13. Right internal jugular vein

14. Left subclavian vein

15. Left internal jugular vein

16. Aortic arch

17. Inferior vena cava

18. General iliac veins(right, left)

Veins of the systemic circulation

Superior vena cava.

The superior vena cava is formed at the level of the first rib at the sternum from the confluence of two, right and left brachiocephalic veins, which in turn collect venous blood from the head of the neck and upper extremities (Fig. 15). The superior vena cava goes down and at the level of the third rib flows into the right atrium. The superior vena cava drains:

1. mediastinal veins;

2. veins of the pericardial sac:

3. azygos vein.

Azygos and semi-azygos veins

The azygos and semi-gypsy veins collect blood mainly from the walls of the abdominal and thoracic cavities. Both veins begin in lower section lumbar region, unpaired - on the right, semi-unpaired - on the left from the ascending lumbar veins.

Right and left ascending lumbar veins are formed at the level of the common iliac veins in the sacral spine, running upward and in front of the transverse processes of the lumbar vertebrae. Here they widely anastomose with the lumbar veins. At the top, the ascending lumbar veins penetrate the chest through the diaphragm, where they change their names to the companion vein, located on the right, semi-unpaired, passing to the left of the spinal column.

Azygos vein directed upward along the right anterolateral surface thoracic spinal column. At the level of the third thoracic vertebra it flows into the superior vena cava. The azygos vein is infused with:

2. bronchial veins, collecting blood from the bronchi;

3. nine posterior intercostal veins, collecting blood from the intercostal spaces;

4. hemizygos vein.

Hemizygos vein runs along the left lateral surface of the spinal column. At the level of the VIII thoracic vertebra it flows into the azygos vein. The hemizygos vein is shorter and somewhat thinner than the azygos vein and receives:

1. veins of the esophagus, collecting blood from the esophagus;

2. mediastinal vein, collecting blood from the mediastinal area;

3. intercostal veins, 4-6, collecting blood from the intercostal spaces;

4. accessory semi-zygos vein, forming from 3-4 upper intercostal veins on the left side.

Inferior vena cava.

The inferior vena cava collects blood from lower limbs, walls and organs of the pelvis, abdominal cavity (Fig. 16). The inferior vena cava begins on the right anterolateral surface of the IV-V lumbar vertebrae from the confluence of two common iliac veins, collecting blood from the lower extremities, walls and pelvic organs.

The inferior vena cava receives two groups of branches: parietal and splanchnic.

I. Parietal branches. These include the following:

1. Lumbar veins - 4 on the left and on the right. They come from the abdominal muscles, lumbar region backs.

2. The inferior vein of the diaphragm is a steam room, accompanies the branches of the artery of the same name on bottom surface diaphragm and flows under the diaphragm into the inferior vena cava.

Figure 16. Inferior vena cava. Figure 17. Portal vein.

1. Inferior vena cava 1. Portal vein

2. Common iliac veins (right, left) 2. Inferior mesenteric vein

3. Lumbar arteries and veins 3. Superior mesenteric vein

4. Lower veins diaphragm 4. Splenic vein

5. Right testicular vein 5. Right branch black vein

6. Left testicular vein 6. Left branch of the crow vein

7. Left renal vein 7. Stomach

8. Left kidney 8. Pancreas

9. Right renal vein 9. Spleen

10. Right adrenal gland 10. Liver

11. Left adrenal gland 11. Duodenum (small intestine)

12. Right suprarenal veins 12. Jejunum (small intestine)

13. Left suprarenal veins 13. Ileum(thin)

14. Hepatic veins 14. Cecum (large)

15. Abdominal aorta 15. Ascending colon (colon)

16. Descending colon (large)

17. Sigmoid colon (large)

19. Hepatic veins

20. Inferior vena cava II. Internal branches. These include the following:

1. Testicular (ovarian) vein. Collects venous blood from male (female) genital organs (Fig. 16).

2. The renal vein is formed in the area of the renal hilum from the confluence of 3-4, and sometimes more, veins emerging from the renal hilum. Renal veins flow into the inferior vena cava at the level of the I and II lumbar vertebrae.

3. The suprarenal veins are formed from small veins that arise from the adrenal gland.

4. The hepatic veins are the last branches that the inferior vena cava receives in the abdominal cavity before entering the right atrium. The hepatic veins collect blood from the capillary system hepatic artery and the portal vein in the thickness of the liver and exit the liver in the region of its posterior edge.

Portal vein system

Portal vein collects blood from the unpaired organs of the abdominal cavity, from the digestive organs and brings it to the liver (Fig. 17). The importance of the portal vein is great, since it is with the help of this vein that toxins and harmful substances are collected from the digestive organs (stomach, intestines), precisely from those organs where they accumulate during human life, and their neutralization and inactivation in the liver. The portal vein is formed behind the head of the pancreas by the confluence of three veins: the inferior mesenteric, superior mesenteric and splenic. The portal vein reaches the portal of the liver, where it divides into two branches (left and right), respectively, by the right and left lobes of the liver.

Inferior mesenteric vein collects blood from the walls of the upper rectum, sigmoid and descending colon.

Upper mesenteric vein collects blood from small intestine and its mesenteries, vermiform appendix and the cecum, ascending and transverse colon.

Splenic vein collects blood from the spleen, stomach and pancreas and

greater omentum.

Thus, all venous blood from the digestive organs of the stomach, pancreas, intestines and spleen enters the portal vein and, passing through the liver, is cleansed at the level of hepatocides from waste, toxins and impurities. After passing through the liver hepatocytes, venous blood, devoid of toxins, is collected in hepatic veins, and along them enters the inferior vena cava.

Lymphatic system. TO lymphatic system include:

1. Large and small lymphatic slits (serous cavities of the peritoneum, pleura, pericardial sac, spaces of the membranes of the brain and spinal cord, cavities of the ventricles of the brain and the central canal of the spinal cord, lymphatic spaces inner ear, chambers of the eye, perineural spaces, joint cavities, etc.).

2. Lymphatic capillaries, which are the thinnest lymphatic vessels. Lymphatic capillaries, repeatedly connecting with each other, form various capillary lymphatic networks in all organs and tissues.

3. Lymphatic vessels are formed from the fusion of lymphatic capillaries. They are equipped a large number paired semilunar valves, allowing lymph flow only in the central direction. There are superficial lymphatic vessels that are located in subcutaneous tissue and deep lymphatic vessels, located mainly along the large arterial trunks. Lymphatic vessels, connecting with each other, form plexuses.

4. Lymph nodes are located along the path of superficial and deep lymphatic vessels and receive lymph from tissues, organs or areas of the body from which the vessels originate (Fig. 18). In a lymph node, there are vessels entering the node and lymph vessels leaving it. Lymph nodes can have a variety of shapes (round, oblong, etc.) and different sizes.

2. Efferent lymphatic 2. Right lumbar lymphatic trunk

3. Porta lymph node 3. Left lumbar lymphatic trunk

4. Lymphoid tissue of the node 4. Intestinal trunk

5. Left subclavian trunk

6. Left jugular trunk

7. Right subclavian trunk

8. Right jugular trunk

9. Right lymphatic duct

10.Superior vena cava

11.Inferior vena cava

12.Intercostal lymphatic vessels

13.Lumbar lymph nodes

14. Iliac lymph nodes

The bulk of the node is formed by lymphoid tissue. Lymph entering the node through afferent vessels washes lymphoid tissue node, is freed here from foreign particles (bacteria, toxins, tumor cells, etc.) etc. enriched with lymphocytes, it flows from the node through the efferent vessels. Lymphatic vessels carrying lymph from regional lymph nodes, are collected in large lymphatic trunks, which ultimately form two large lymphatic ducts: thoracic duct and the right lymphatic duct.

Thoracic lymphatic duct.

The thoracic duct has a length of 35-45 cm, collects lymph from both lower extremities, from the organs and walls of the pelvis, from the abdominal cavity, from the left lung, from the left half of the heart, from the walls of the left half of the chest, from the left upper limb and the left half of the neck and head. The thoracic duct is formed in the abdominal cavity at the level of the II lumbar vertebra from the confluence of 3 lymphatic vessels: the left lumbar lymphatic trunk, the right lumbar lymphatic trunk and the unpaired intestinal lymphatic trunk (Fig. 19).

Left and right lumbar trunks collect lymph from the lower extremities, walls and organs of the pelvic cavity, abdominal cavity, lumbar and sacral regions spinal canal and spinal cord membranes.

Intestinal trunk collects lymph from all abdominal organs.

The thoracic duct carries lymph from the bottom up and, together with the aorta, passes through the aortic opening of the diaphragm into the chest cavity. In the chest cavity, the thoracic duct runs along the anterior surface of the vertebral bodies and then flows into the left venous angle, the junction of the left internal jugular vein and left subclavian vein. In the chest cavity, the thoracic lymphatic duct receives lymph from small intercostal lymphatic vessels, and also the large left bronchomediastinal trunk flows into it, from organs located in the left half of the chest (left lung, left half of the heart, esophagus, larynx) and thyroid gland(Fig. 15, 19, 25).

In the subclavian region on the left, at the point of confluence with the left venous angle, the thoracic duct receives lymphatic fluid from 3 large lymphatic vessels:

1. left subclavian trunk, collecting lymph from the left upper limb;

2. the left jugular trunk, which collects lymph from the left half of the head and neck;

3. the left internal trunk of the mammary gland, which collects lymph from the left half of the chest, diaphragm and liver.

Along the duct lies a large number of lymph nodes.

Lymphatic vessels and nodes of the abdominal cavity.

Right and left lumbar lymphatic trunks lymph is collected from the abdominal cavity, organs and muscles of the pelvis, and lower extremities.

Intestinal trunk collects lymph from thick loops, small intestine, kidneys, adrenal glands, liver, spleen, pancreas, stomach.

Lymphatic vessels and nodes of the chest cavity.

Lymph from intercostal spaces, diaphragm, thyroid gland, larynx, trachea, esophagus, bronchi, lungs, heart, liver enters the left or right bronchomediastinal trunk, or the left or right inner trunk mammary gland; and then - into the thoracic or right lymphatic duct.