What kind of blood is in the arteries of the systemic circulation. Circulation

The regularity of the movement of blood in the circles of blood circulation was discovered by Harvey (1628). Subsequently, the doctrine of the physiology and anatomy of blood vessels was enriched with numerous data that revealed the mechanism of general and regional blood supply to organs.

In goblin animals and humans with a four-chambered heart, there are large, small and cardiac circles of blood circulation (Fig. 367). The heart plays a central role in circulation.

367. Scheme of blood circulation (according to Kishsh, Sentagotai).

1 - common carotid artery;
2 - aortic arch;
3 - pulmonary artery;
4 - pulmonary vein;
5 - left ventricle;
6 - right ventricle;
7 - celiac trunk;
8 - superior mesenteric artery;
9 - inferior mesenteric artery;
10 - inferior vena cava;
11 - aorta;
12 - common iliac artery;
13 - common iliac vein;
14 - femoral vein. 15 - portal vein;
16 - hepatic veins;
17 - subclavian vein;
18 - superior vena cava;
19 - internal jugular vein.

Small circle of blood circulation (pulmonary)

Venous blood from the right atrium through the right atrioventricular opening passes into the right ventricle, which, contracting, pushes the blood into the pulmonary trunk. It divides into the right and left pulmonary arteries, which enter the lungs. In lung tissue, the pulmonary arteries divide into capillaries that surround each alveolus. After the erythrocytes release carbon dioxide and enrich them with oxygen, venous blood turns into arterial blood. Arterial blood flows through four pulmonary veins (two veins in each lung) into the left atrium, then through the left atrioventricular opening passes into the left ventricle. The systemic circulation begins from the left ventricle.

Systemic circulation

Arterial blood from the left ventricle during its contraction is ejected into the aorta. The aorta splits into arteries that supply blood to the limbs, torso, and. all internal organs and ending in capillaries. Nutrients, water, salts and oxygen are released from the blood of capillaries into the tissues, metabolic products and carbon dioxide are resorbed. Capillaries gather into venules, where the venous vascular system begins, representing the roots of the superior and inferior vena cava. Venous blood through these veins enters the right atrium, where the systemic circulation ends.

Cardiac circulation

This circle of blood circulation begins from the aorta with two coronary cardiac arteries, through which blood enters all layers and parts of the heart, and then is collected through small veins into the venous coronary sinus. This vessel with a wide mouth opens into the right atrium. Part of the small veins of the heart wall directly opens into the cavity of the right atrium and ventricle of the heart.

Heart is the central organ of blood circulation. It is a hollow muscular organ, consisting of two halves: left - arterial and right - venous. Each half consists of interconnected atria and ventricle of the heart.
The central organ of blood circulation is heart. It is a hollow muscular organ, consisting of two halves: left - arterial and right - venous. Each half consists of interconnected atria and ventricle of the heart.

Venous blood through the veins enters the right atrium and then to the right ventricle of the heart, from the latter to the pulmonary trunk, from where it follows the pulmonary arteries to the right and left lungs. Here the branches of the pulmonary arteries branch to the smallest vessels - capillaries.

In the lungs, venous blood is saturated with oxygen, becomes arterial, and is sent through four pulmonary veins to the left atrium, then enters the left ventricle of the heart. From the left ventricle of the heart, blood enters the largest arterial highway - the aorta, and along its branches, which decay in the tissues of the body to the capillaries, it spreads throughout the body. Having given oxygen to the tissues and taking carbon dioxide from them, the blood becomes venous. Capillaries, reconnecting with each other, form veins.

All veins of the body are connected into two large trunks - the superior vena cava and the inferior vena cava. AT superior vena cava blood is collected from areas and organs of the head and neck, upper limbs and some parts of the walls of the body. The inferior vena cava is filled with blood from the lower extremities, walls and organs of the pelvic and abdominal cavities.

Systemic circulation video.

Both vena cava bring blood to the right atrium, which also receives venous blood from the heart itself. This closes the circle of blood circulation. This blood path is divided into a small and a large circle of blood circulation.

Small circle of blood circulation video

Small circle of blood circulation(pulmonary) starts from the right ventricle of the heart with the pulmonary trunk, includes branches of the pulmonary trunk to the capillary network of the lungs and pulmonary veins that flow into the left atrium.

Systemic circulation(bodily) starts from the left ventricle of the heart by the aorta, includes all its branches, capillary network and veins of organs and tissues of the whole body and ends in the right atrium.
Consequently, blood circulation takes place in two interconnected circles of blood circulation.

The cardiovascular system includes two systems: the circulatory (circulatory system) and the lymphatic (lymphatic circulation system). The circulatory system combines the heart and blood vessels - tubular organs in which blood circulates throughout the body. The lymphatic system includes lymphatic capillaries branched in organs and tissues, lymphatic vessels, lymphatic trunks and lymphatic ducts, through which lymph flows towards large venous vessels.

Along the route of the lymphatic vessels from the organs and parts of the body to the trunks and ducts, there are numerous lymph nodes related to the organs of the immune system. The study of the cardiovascular system is called angiocardiology. The circulatory system is one of the main systems of the body. It ensures the delivery of nutrients, regulatory, protective substances, oxygen to tissues, the removal of metabolic products, and heat transfer. It is a closed vascular network penetrating all organs and tissues, and having a centrally located pumping device - the heart.

The circulatory system is connected by numerous neurohumoral connections with the activity of other body systems, serves as an important link in homeostasis and provides blood supply adequate to current local needs. For the first time, an accurate description of the mechanism of blood circulation and the significance of the heart was given by the founder of experimental physiology, the English physician W. Harvey (1578-1657). In 1628, he published the well-known work Anatomical Study of the Movement of the Heart and Blood in Animals, in which he provided evidence of the movement of blood through the vessels of the systemic circulation.

The founder of scientific anatomy A. Vesalius (1514-1564) in his work "On the structure of the human body" gave a correct description of the structure of the heart. The Spanish physician M. Servet (1509-1553) in the book "Restoration of Christianity" correctly presented the pulmonary circulation, describing the path of blood flow from the right ventricle to the left atrium.

The blood vessels of the body are combined into a large and small circles of blood circulation. In addition, the coronary circulation is additionally isolated.

1)Systemic circulation - bodily starts from the left ventricle of the heart. It includes the aorta, arteries of various sizes, arterioles, capillaries, venules and veins. The large circle ends with two vena cava, flowing into the right atrium. Through the walls of the capillaries of the body there is an exchange of substances between the blood and tissues. Arterial blood gives oxygen to the tissues and, saturated with carbon dioxide, turns into venous blood. Usually, an arterial type vessel (arteriole) approaches the capillary network, and a venule leaves it.

For some organs (kidney, liver), there is a deviation from this rule. So, an artery, an afferent vessel, approaches the glomerulus of the renal corpuscle. An artery also leaves the glomerulus - the efferent vessel. A capillary network inserted between two vessels of the same type (arteries) is called arterial miraculous network. According to the type of miraculous network, a capillary network was built, located between the afferent (interlobular) and efferent (central) veins in the liver lobule - venous miraculous network.

2)Small circle of blood circulation - pulmonary starts from the right ventricle. It includes the pulmonary trunk, which branches into two pulmonary arteries, smaller arteries, arterioles, capillaries, venules, and veins. It ends with four pulmonary veins that empty into the left atrium. In the capillaries of the lungs, venous blood, enriched with oxygen and freed from carbon dioxide, turns into arterial blood.

3)coronary circulation - cordial , includes the vessels of the heart itself for the blood supply to the heart muscle. It begins with the left and right coronary arteries, which depart from the initial section of the aorta - the aortic bulb. Flowing through the capillaries, the blood gives oxygen and nutrients to the heart muscle, receives metabolic products, including carbon dioxide, and turns into venous blood. Almost all veins of the heart flow into a common venous vessel - the coronary sinus, which opens into the right atrium.

Only a small number of the so-called smallest veins of the heart flows independently, bypassing the coronary sinus, into all chambers of the heart. It should be noted that the heart muscle needs a constant supply of a large amount of oxygen and nutrients, which is provided by a rich blood supply to the heart. With a heart mass of only 1/125-1/250 of body weight, 5-10% of all blood ejected into the aorta enters the coronary arteries.

In the human body, blood moves through two closed systems of vessels connected to the heart - small and big circles of blood circulation.

Small circle of blood circulation is the path of blood from the right ventricle to the left atrium.

Venous, oxygen-poor blood flows to the right side of the heart. shrinking right ventricle throws it into pulmonary artery. The two branches into which the pulmonary artery divides carry this blood to easy. There, the branches of the pulmonary artery, dividing into smaller and smaller arteries, pass into capillaries, which densely braid numerous pulmonary vesicles containing air. Passing through the capillaries, the blood is enriched with oxygen. At the same time, carbon dioxide from the blood passes into the air, which fills the lungs. Thus, in the capillaries of the lungs, venous blood turns into arterial blood. It enters the veins, which, connecting with each other, form four pulmonary veins that fall into left atrium(Fig. 57, 58).

The time of blood circulation in the pulmonary circulation is 7-11 seconds.

Systemic circulation - this is the path of blood from the left ventricle through the arteries, capillaries and veins to the right atrium.material from the site

The left ventricle contracts to push arterial blood into aorta- the largest human artery. Arteries branch from it, which supply blood to all organs, in particular to the heart. The arteries in each organ gradually branch out, forming dense networks of smaller arteries and capillaries. From the capillaries of the systemic circulation, oxygen and nutrients enter all tissues of the body, and carbon dioxide passes from the cells into the capillaries. In this case, the blood is converted from arterial to venous. Capillaries merge into veins, first into small ones, and then into larger ones. Of these, all the blood is collected in two large vena cava. superior vena cava carries blood to the heart from the head, neck, hands, and inferior vena cava- from all other parts of the body. Both vena cava flow into the right atrium (Fig. 57, 58).

The time of blood circulation in the systemic circulation is 20-25 seconds.

Venous blood from the right atrium enters the right ventricle, from which it flows through the pulmonary circulation. When the aorta and pulmonary artery exit from the ventricles of the heart, semilunar valves(Fig. 58). They look like pockets placed on the inner walls of blood vessels. When blood is pushed into the aorta and pulmonary artery, the semilunar valves are pressed against the walls of the vessels. When the ventricles relax, the blood cannot return to the heart due to the fact that, flowing into the pockets, it stretches them and they close tightly. Therefore, the semilunar valves ensure the movement of blood in one direction - from the ventricles to the arteries.

On this page, material on the topics:

Circles of blood circulation lecture notes
Report on the human circulatory system
Lectures circles of blood circulation diagram of animals
Blood circulation large and small circles of blood circulation cheat sheet
Benefits of two circulations over one

Questions about this item:

The large and small circles of blood circulation were discovered by Harvey in 1628. Later, scientists from many countries made important discoveries regarding the anatomical structure and functioning of the circulatory system. To this day, medicine is moving forward, studying methods of treatment and restoration of blood vessels. Anatomy is enriched with new data. They reveal to us the mechanisms of general and regional blood supply to tissues and organs. A person has a four-chambered heart, which makes blood circulate through the systemic and pulmonary circulation. This process is continuous, thanks to it absolutely all cells of the body receive oxygen and important nutrients.

Meaning of blood

Large and small circles of blood circulation deliver blood to all tissues, thanks to which our body functions properly. Blood is a connecting element that ensures the vital activity of every cell and every organ. Oxygen and nutrients, including enzymes and hormones, enter the tissues, and metabolic products are removed from the intercellular space. In addition, it is the blood that provides a constant temperature of the human body, protecting the body from pathogenic microbes.

From the digestive organs, nutrients continuously enter the blood plasma and are carried to all tissues. Despite the fact that a person constantly consumes food containing a large amount of salts and water, a constant balance of mineral compounds is maintained in the blood. This is achieved by removing excess salts through the kidneys, lungs and sweat glands.

Heart

Large and small circles of blood circulation depart from the heart. This hollow organ consists of two atria and ventricles. The heart is located on the left side of the chest. Its weight in an adult, on average, is 300 g. This organ is responsible for pumping blood. There are three main phases in the work of the heart. Contraction of the atria, ventricles and a pause between them. This takes less than one second. In one minute, the human heart beats at least 70 times. Blood moves through the vessels in a continuous stream, constantly flows through the heart from a small circle to a large one, carrying oxygen to organs and tissues and bringing carbon dioxide into the alveoli of the lungs.

Systemic (large) circulation

Both large and small circles of blood circulation perform the function of gas exchange in the body. When the blood returns from the lungs, it is already enriched with oxygen. Further, it must be delivered to all tissues and organs. This function is performed by a large circle of blood circulation. It originates in the left ventricle, bringing blood vessels to the tissues, which branch into small capillaries and carry out gas exchange. The systemic circle ends in the right atrium.

Anatomical structure of the systemic circulation

The systemic circulation originates in the left ventricle. Oxygenated blood comes out of it into large arteries. Getting into the aorta and the brachiocephalic trunk, it rushes to the tissues with great speed. One large artery to the upper body, and the second to the lower.

The brachiocephalic trunk is a large artery separated from the aorta. It carries oxygen-rich blood up to the head and arms. The second large artery - the aorta - delivers blood to the lower body, to the legs and tissues of the body. These two main blood vessels, as mentioned above, are repeatedly divided into smaller capillaries, which penetrate organs and tissues like a mesh. These tiny vessels deliver oxygen and nutrients to the intercellular space. From it, carbon dioxide and other metabolic products necessary for the body enter the bloodstream. On the way back to the heart, the capillaries reconnect into larger vessels - veins. The blood in them flows more slowly and has a dark tint. Ultimately, all the vessels coming from the lower body are combined into the inferior vena cava. And those that go from the upper body and head - into the superior vena cava. Both of these vessels enter the right atrium.

Small (pulmonary) circulation

The pulmonary circulation originates in the right ventricle. Further, having made a complete revolution, the blood passes into the left atrium. The main function of the small circle is gas exchange. Carbon dioxide is removed from the blood, which saturates the body with oxygen. The process of gas exchange is carried out in the alveoli of the lungs. Small and large circles of blood circulation perform several functions, but their main significance is to conduct blood throughout the body, covering all organs and tissues, while maintaining heat exchange and metabolic processes.

Lesser circle anatomical device

From the right ventricle of the heart comes venous, oxygen-poor blood. It enters the largest artery of the small circle - the pulmonary trunk. It divides into two separate vessels (right and left arteries). This is a very important feature of the pulmonary circulation. The right artery brings blood to the right lung, and the left, respectively, to the left. Approaching the main organ of the respiratory system, the vessels begin to divide into smaller ones. They branch until they reach the size of thin capillaries. They cover the entire lung, increasing thousands of times the area on which gas exchange occurs.

Each tiny alveolus has a blood vessel. Only the thinnest wall of the capillary and the lung separates blood from atmospheric air. It is so delicate and porous that oxygen and other gases can freely circulate through this wall into the vessels and alveoli. This is how gas exchange takes place. The gas moves according to the principle from a higher concentration to a lower one. For example, if there is very little oxygen in the dark venous blood, then it begins to enter the capillaries from atmospheric air. But with carbon dioxide, the opposite happens, it passes into the alveoli of the lung, since its concentration is lower there. Further, the vessels are again combined into larger ones. Ultimately, only four large pulmonary veins remain. They carry oxygenated, bright red arterial blood to the heart, which flows into the left atrium.

Circulation time

The period of time during which the blood has time to pass through the small and large circle is called the time of the complete circulation of blood. This indicator is strictly individual, but on average it takes from 20 to 23 seconds at rest. With muscle activity, for example, while running or jumping, the blood flow speed increases several times, then a complete blood circulation in both circles can take place in just 10 seconds, but the body cannot withstand such a pace for a long time.

Cardiac circulation

The large and small circles of blood circulation provide gas exchange processes in the human body, but blood also circulates in the heart, and along a strict route. This path is called the “cardiac circulation”. It begins with two large coronary cardiac arteries from the aorta. Through them, blood enters all parts and layers of the heart, and then through small veins is collected in the venous coronary sinus. This large vessel opens into the right heart atrium with its wide mouth. But some of the small veins directly exit into the cavity of the right ventricle and atrium of the heart. This is how the circulatory system of our body is arranged.

Most people do not know how many circles of blood circulation a person has. Below is detailed information about the bodies responsible for the operation of the system and other nuances.

People have long been interested in the blood flow system and have explored it many centuries ago. There are many scientific works of famous scientists on this topic. Around the middle of the 17th century, it was proven that human blood circulates. Further studies of the circulatory system and organs involved in this process continued. Over time, they learned to treat ailments associated with blood flow.

There are two important circles of blood circulation in a person - it's big and small. They interact with each other, since the human body is integral.

In contact with

Circulatory organs

We include among them:

vessels.

The heart is very important organ for life, as well as in the stage of human circulation. Therefore, it is so important to monitor its activity and consult a doctor in a timely manner in case of malfunctions. The composition of the most important organ includes four chambers, it consists of two ventricles and how many atria. They are connected by partitions. You can say this: the heart is a big muscle. It constantly pulsates or, as we say, beats.

Important! If your limbs go numb or your speech drags on, you need to call an ambulance as soon as possible. Maybe it's a stroke.

Vessels are important participants in the process of blood flow, they transport nutrients with fluid to all organs and tissues like pipes. Vessels consist of three layers of tissue. All of them perform their important function.

Circulatory organs interconnected.

Vessel groups

Are divided into three groups:

arteries;
veins;
capillaries.

The artery is largest type of vessels. They are very elastic. The movement of fluid through them occurs in a certain rhythm and under a certain pressure. Normal blood pressure for a person should be 120/80 mm. mercury column.

If there are pathologies in the body, then the rhythm can go astray, the pressure can drop, or vice versa grow. Some people have high blood pressure on a regular basis, this disease is called hypertension. There are people with chronically low blood pressure - hypotension.

Injuries to the arteries are very dangerous and pose a threat to human life, it is urgent to call an ambulance. It is important to stop bleeding in time. You have to put on a tourniquet. From damaged arteries blood gushes out.

Capillaries - come off the arteries they are much thinner. Also elastic. Through them, blood flows directly to the organs, to the skin. Capillaries are very fragile, and due to the fact that they are located in the upper layers of the skin, they are easy to damage and injure. Damage to the capillaries for an ordinary organism without disturbances in the circulatory system is not dangerous and does not require the help of doctors.

Veins are vessels that carry blood comes back, ending the cycle. Through the veins, a liquid enriched with all the necessary useful substances moves back to the heart. Veins are medium in thickness vessels. Like other vessels, they are elastic. Injuries to the veins also require medical attention, although they are less dangerous than injuries to the arteries.

Briefly about the circulatory system

Already mentioned above, there big and small circulation circle. In other words, bodily (large) and pulmonary (respectively small). The systemic circulation begins in the left ventricle.

Blood is launched into the widest artery in diameter - the aorta, then spreads through other arteries, then through capillaries and goes to peripheral tissues and to all organs.

The blood is saturated with useful substances, after which it is launched into the veins. Through the veins, blood returns to the heart, namely, to the right atrium. This system of blood flow is called the bodily system, because the vessels supply blood to parts of the body. Veins of the systemic circulation come from all organs. Where the systemic circulation begins, there is an increased pulse, because the aorta is the thickest of all vessels.

Attention! More and more people have problems with the cardiovascular system. Now even children suffer from vascular diseases. Stroke is no longer a problem for adults!

The arteries of the systemic circulation diverge into all parts of the body.

The human body is permeated with an uncountable number of capillaries that are kilometers long. The veins of the systemic circulation complete the cycle.

On the diagram, you can clearly see how the human circulatory system works and what happens, where the systemic circulation begins, where are the boundaries between veins and arteries.

Small circle of blood circulation

It is also called lung. The name is so because the blood in this circle is supplied to the respiratory system, in particular the lungs. The pulmonary circulation starts in the right ventricle, then goes to the respiratory organs. Its purpose is oxygenate the blood and remove CO2.

What is the small circle

The pulmonary circulation includes the following elements:

Right ventricle;
Left atrium;
Lungs;
arteries;
capillaries;
Vienna.

Those small vessels that diverge from the arteries, penetrate the lungs, passing through all the alveoli - these are bubbles with pure. System Paradox of this circle - venous blood is pumped through the arteries, and arterial blood goes through the veins.

Strong emotions always lead to increased pressure and increased blood flow. In different vessels, the speed of fluid movement is different. The wider the vessel, the higher the speed, and vice versa. So it turns out that in the aorta the speed of movement is very high. In capillaries, it is ten times lower.

If there is not enough pressure, then the blood does not supply distant areas well, for example, it does not flow to the limbs. it leads to discomfort sometimes leading to serious health problems. For example, Reine's syndrome is associated precisely with the lack of blood flow to the fingers. The simplest thing that worries people with poor blood flow is constantly cold extremities. Nerve endings constantly suffer from this, not receiving useful substances.

Heartbeat

Interestingly, at rest we do not notice how our heart beats. Moreover, it does not bring us discomfort. And after physical activity, we hear how this organ knocks. He pumps blood more intense and faster.

People with different fitness levels respond differently to exercise. In some students, the pulse is very strong, in others it is not so pronounced. For some groups of the inhabitants of the planet, sports are contraindicated due to heart problems.

And for those who are allowed to exercise, you need to remember that the heart is a muscle, which means it requires constant training. Exercise is excellent for the functioning of the cardiovascular system. It gives energy for the whole day. You can go to the gym or work out at home. Swimming is a great exercise for the heart.

Attention! In smokers, the blood is enriched with oxygen much worse, this negatively affects the entire functioning of the body. They are much more likely to suffer from diseases of the heart system!

In addition to the above-mentioned circles, there are even less known circles of blood circulation - the heart and the circle of Willis. The first one provides blood flow around the heart.

In our body blood continuously moves along a closed system of vessels in a strictly defined direction. This continuous movement of blood is called blood circulation. Circulatory system a person is closed and has 2 circles of blood circulation: large and small. The main organ that ensures the movement of blood is the heart.

The circulatory system is made up of hearts and vessels. Vessels are of three types: arteries, veins, capillaries.

Heart- a hollow muscular organ (weighing about 300 grams) about the size of a fist, located in the chest cavity on the left. The heart is surrounded by a pericardial sac formed by connective tissue. Between the heart and the pericardial sac is a fluid that reduces friction. Humans have a four-chambered heart. The transverse septum divides it into left and right halves, each of which is separated by valves neither an atrium and a ventricle. The walls of the atria are thinner than the walls of the ventricles. The walls of the left ventricle are thicker than the walls of the right ventricle, as it does a lot of work, pushing blood into the systemic circulation. At the border between the atria and ventricles, there are cuspid valves that prevent the backflow of blood.

The heart is surrounded by a pericardial sac (pericardium). The left atrium is separated from the left ventricle by a bicuspid valve, and the right atrium is separated from the right ventricle by a tricuspid valve.

Strong tendon filaments are attached to the valve leaflets from the side of the ventricles. Their design does not allow blood to move from the ventricles to the atrium during the contraction of the ventricle. At the base of the pulmonary artery and aorta are the semilunar valves, which prevent blood from flowing back from the arteries back into the ventricles.

The right atrium receives venous blood from the systemic circulation, while the left atrium receives arterial blood from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, to the left - arterial from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, its walls are about three times thicker than the walls of the right ventricle. The cardiac muscle is a special type of striated muscle in which the muscle fibers grow together at the ends and form a complex network. This structure of the muscle increases its strength and accelerates the passage of the nerve impulse (the entire muscle reacts simultaneously). Cardiac muscle differs from skeletal muscles in its ability to contract rhythmically in response to impulses originating in the heart itself. This phenomenon is called automation.

arteries Vessels that carry blood away from the heart. Arteries are thick-walled vessels, the middle layer of which is represented by elastic and smooth muscles, so the arteries are able to withstand significant blood pressure and not rupture, but only stretch.

The smooth muscles of the arteries perform not only a structural role, but its contractions contribute to the fastest blood flow, since the power of only one heart would not be enough for normal blood circulation. There are no valves inside the arteries, the blood flows quickly.

Vienna- Vessels that carry blood to the heart. The walls of the veins also have valves that prevent backflow of blood.

Veins are thinner-walled than arteries and have fewer elastic fibers and muscle elements in the middle layer.

The blood through the veins does not flow completely passively, the surrounding muscles make pulsating movements and drive the blood through the vessels to the heart. Capillaries are the smallest blood vessels, through which blood plasma exchanges nutrients with tissue fluid. The capillary wall consists of a single layer of flat cells. The membranes of these cells have multi-membered tiny holes that facilitate the passage of substances involved in the exchange through the capillary wall.

Blood movement occurs in two circles of blood circulation.

Systemic circulation- this is the path of blood from the left ventricle to the right atrium: left ventricle aorta thoracic aorta abdominal aorta arteries capillaries in organs (gas exchange in tissues) veins superior (inferior) vena cava right atrium

Small circle of blood circulation- the path from the right ventricle to the left atrium: right ventricle pulmonary trunk artery right (left) pulmonary capillaries in the lungs gas exchange in the lungs pulmonary veins left atrium

In the pulmonary circulation, venous blood moves through the pulmonary arteries, and arterial blood moves through the pulmonary veins after gas exchange in the lungs.

367. Scheme of blood circulation (according to Kishsh, Sentagotai).

1 - common carotid artery;

2 - aortic arch;

8 - superior mesenteric artery;

Small circle of blood circulation (pulmonary)

Systemic circulation

Arterial blood from the left ventricle during its contraction is ejected into the aorta. The aorta splits into arteries that supply blood to the limbs and torso. all internal organs and ending in capillaries. Nutrients, water, salts and oxygen are released from the blood of capillaries into the tissues, metabolic products and carbon dioxide are resorbed. Capillaries gather into venules, where the venous vascular system begins, representing the roots of the superior and inferior vena cava. Venous blood through these veins enters the right atrium, where the systemic circulation ends.

Cardiac circulation

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circulatory and lymphatic systems

Blood plays the role of a connecting element that ensures the vital activity of every organ, every cell. Thanks to the blood circulation, oxygen and nutrients, as well as hormones, enter all tissues and organs, and the decay products of substances are removed. In addition, blood maintains a constant body temperature and protects the body from harmful microbes.

Blood is a fluid connective tissue composed of blood plasma (approximately 54% by volume) and cells (46% by volume). Plasma is a yellowish translucent liquid containing 90-92% water and 8-10% proteins, fats, carbohydrates and some other substances.

From the digestive organs, nutrients enter the blood plasma, which are carried to all organs. Despite the fact that a large amount of water and mineral salts enter the human body with food, a constant concentration of minerals is maintained in the blood. This is achieved by the release of an excess amount of chemical compounds through the kidneys, sweat glands, and lungs.

The movement of blood in the human body is called circulation. Continuity of blood flow is provided by the circulatory organs, which include the heart and blood vessels. They make up the circulatory system.

The human heart is a hollow muscular organ consisting of two atria and two ventricles. It is located in the chest cavity. The left and right sides of the heart are separated by a continuous muscular septum. The weight of an adult human heart is approximately 300 g.

The life and health of a person largely depend on the normal functioning of his heart. It pumps blood through the vessels of the body, maintaining the viability of all organs and tissues. The evolutionary structure of the human heart - the scheme, circles of blood circulation, the automatism of the cycles of contractions and relaxation of the muscle cells of the walls, the operation of the valves - everything is subordinated to the fulfillment of the main task of uniform and sufficient blood circulation.

The structure of the human heart - anatomy

The organ, thanks to which the body is saturated with oxygen and nutrients, is an anatomical cone-shaped formation located in the chest, mostly on the left. Inside the organ, a cavity divided into four unequal parts by partitions is two atria and two ventricles. The former collect blood from the veins flowing into them, while the latter push it into the arteries outgoing from them. Normally, in the right side of the heart (atrium and ventricle) there is oxygen-poor blood, and in the left - oxygenated.

atrium

Right (PP). It has a smooth surface, the volume is 100-180 ml, including an additional formation - the right ear. Wall thickness 2-3 mm. Vessels flow into the PP:

superior vena cava,
cardiac veins - through the coronary sinus and pinholes of small veins,
inferior vena cava.

Left (LP). The total volume, including the ear, is 100-130 ml, the walls are also 2-3 mm thick. The LP receives blood from four pulmonary veins.

The atria are separated by the interatrial septum (IAS), which normally does not have any openings in adults. They communicate with the cavities of the corresponding ventricles through openings equipped with valves. On the right - tricuspid tricuspid, on the left - bicuspid mitral.

Ventricles

Right (RV) cone-shaped, base facing upwards. Wall thickness up to 5 mm. The inner surface in the upper part is smoother, closer to the top of the cone it has a large number of muscle cords-trabeculae. In the middle part of the ventricle, there are three separate papillary (papillary) muscles, which, by means of tendinous filaments-chords, keep the cusps of the tricuspid valve from deflecting them into the atrial cavity. The chords also depart directly from the muscular layer of the wall. At the base of the ventricle are two openings with valves:

serving as an outlet for blood into the pulmonary trunk,
connecting the ventricle to the atrium.

Left (LV). This section of the heart is surrounded by the most impressive wall, the thickness of which is 11-14 mm. The LV cavity is also cone-shaped and has two openings:

atrioventricular with bicuspid mitral valve,
outlet to the aorta with a tricuspid aortic.

The muscle cords in the region of the apex of the heart and the papillary muscles supporting the leaflets of the mitral valve are more powerful here than similar structures in the pancreas.

shells of the heart

To protect and ensure the movements of the heart in the chest cavity, it is surrounded by a heart shirt - the pericardium. Directly in the wall of the heart there are three layers - epicardium, endocardium, myocardium.

The pericardium is called the heart bag, it is loosely attached to the heart, its outer leaf is in contact with neighboring organs, and the inner one is the outer layer of the heart wall - the epicardium. Composition: connective tissue. A small amount of fluid is normally present in the pericardial cavity for better glide of the heart.
The epicardium also has a connective tissue base, accumulations of fat are observed in the region of the apex and along the coronal sulci, where the vessels are located. In other places, the epicardium is firmly connected with the muscle fibers of the main layer.
The myocardium makes up the main thickness of the wall, especially in the most loaded zone - the region of the left ventricle. Muscle fibers located in several layers run both longitudinally and in a circle, ensuring uniform contraction. The myocardium forms trabeculae in the region of the apex of both ventricles and papillary muscles, from which tendon chords extend to the valve leaflets. The muscles of the atria and ventricles are separated by a dense fibrous layer, which also serves as a framework for the atrioventricular (atrioventricular) valves. The interventricular septum consists of 4/5 of the length of the myocardium. In the upper part, called membranous, its basis is connective tissue.
Endocardium - a sheet that covers all the internal structures of the heart. It is three-layered, one of the layers is in contact with the blood and is similar in structure to the endothelium of the vessels that enter and exit the heart. Also in the endocardium there is connective tissue, collagen fibers, smooth muscle cells.

All heart valves are formed from the folds of the endocardium.

Human heart structure and functions

The pumping of blood by the heart into the vascular bed is provided by the features of its structure:

the heart muscle is capable of automatic contraction,
the conducting system guarantees the constancy of the cycles of excitation and relaxation.

How does the cardiac cycle work?

It consists of three consecutive phases: general diastole (relaxation), atrial systole (contraction), and ventricular systole.

General diastole is a period of physiological pause in the work of the heart. At this time, the heart muscle is relaxed, and the valves between the ventricles and atria are open. From the venous vessels, blood freely fills the cavities of the heart. The valves of the pulmonary artery and aorta are closed.
Atrial systole occurs when the pacemaker in the atrial sinus node is automatically excited. At the end of this phase, the valves between the ventricles and the atria close.
The systole of the ventricles takes place in two stages - isometric tension and expulsion of blood into the vessels.
The period of tension begins with an asynchronous contraction of the muscle fibers of the ventricles until the moment of complete closure of the mitral and tricuspid valves. Then, in the isolated ventricles, tension begins to grow, pressure rises.
When it becomes higher than in the arterial vessels, the period of exile is initiated - the valves open, releasing blood into the arteries. At this time, the muscle fibers of the walls of the ventricles are intensively reduced.
Then the pressure in the ventricles decreases, the arterial valves close, which corresponds to the beginning of diastole. During the period of complete relaxation, the atrioventricular valves open.

The conduction system, its structure and the work of the heart

The conduction system of the heart provides contraction of the myocardium. Its main feature is the automatism of cells. They are able to self-excite in a certain rhythm, depending on the electrical processes that accompany cardiac activity.

As part of the conduction system, the sinus and atrioventricular nodes, the underlying bundle and branchings of His, Purkinje fibers are interconnected.

sinus node. Normally generates an initial impulse. It is located in the area of the mouth of both hollow veins. From it, excitation passes to the atria and is transmitted to the atrioventricular (AV) node.
The atrioventricular node propagates the impulse to the ventricles.
The bundle of His is a conductive "bridge" located in the interventricular septum, where it is also divided into the right and left legs, which transmit excitation to the ventricles.
Purkinje fibers are the terminal part of the conduction system. They are located near the endocardium and are in direct contact with the myocardium, causing it to contract.

The structure of the human heart: diagram, circles of blood circulation

The task of the circulatory system, the main center of which is the heart, is the delivery of oxygen, nutrients and bioactive components to the tissues of the body and the elimination of metabolic products. To do this, the system provides a special mechanism - the blood moves through the circles of blood circulation - small and large.

small circle

From the right ventricle at the time of systole, venous blood is pushed into the pulmonary trunk and enters the lungs, where it is saturated with oxygen in the microvessels of the alveoli, becoming arterial. It flows into the cavity of the left atrium and enters the system of a large circle of blood circulation.

big circle

From the left ventricle into systole, arterial blood through the aorta and further through vessels of different diameters enters various organs, giving them oxygen, transferring nutrients and bioactive elements. In small tissue capillaries, the blood turns into venous blood, as it is saturated with metabolic products and carbon dioxide. Through the system of veins, it flows to the heart, filling its right sections.

Nature has worked hard to create such a perfect mechanism, giving it a margin of safety for many years. Therefore, you should carefully treat it so as not to create problems with blood circulation and your own health.

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Defunct page

The structure of the human heart - anatomy

atrium

Ventricles

shells of the heart

Human heart structure and functions

How does the cardiac cycle work?

The conduction system, its structure and the work of the heart

The structure of the human heart: diagram, circles of blood circulation

small circle

big circle