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

The pattern of blood movement in circulatory circles 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, which have a four-chambered heart, a distinction is made between the greater, lesser and cardiac circles of blood circulation (Fig. 367). The heart occupies a central place in blood circulation.

367. Blood circulation diagram (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 - top mesenteric artery;
9 - inferior mesenteric artery;
10 - inferior vena cava;
11 - aorta;
12 - total iliac artery;
13 - general iliac vein;
14 - femoral vein. 15 - portal vein;
16 - hepatic veins;
17 - subclavian vein;
18 - superior vena cava;
19 - internal jugular vein.



Pulmonary circulation (pulmonary)

Venous blood from the right atrium passes through the right atrioventricular orifice into the right ventricle, which contracts and pushes blood into the pulmonary trunk. It divides into the right and left pulmonary arteries, which enter the lungs. In the lung tissue, the pulmonary arteries are divided into capillaries surrounding each alveolus. After red blood cells release carbon dioxide and enrich them with oxygen venous blood turns into arterial. Arterial blood flows through four pulmonary veins (there are two veins in each lung) into the left atrium, then passes through the left atrioventricular orifice into the left ventricle. The systemic circulation begins from the left ventricle.

Systemic circulation

Arterial blood from the left ventricle is ejected into the aorta during its contraction. The aorta splits into arteries that supply blood to the limbs and torso. all internal organs and ending with capillaries. Nutrients, water, salts and oxygen are released from the blood capillaries into the tissues, metabolic products and carbon dioxide are resorbed. The capillaries gather into venules, where it begins venous system vessels, representing the roots of the superior and inferior vena cava. Venous blood flows through these veins into 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 collects through small veins into the venous coronary sinus. This vessel opens with a wide mouth into the right atrium. Some of the small veins of the heart wall directly open 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 an interconnected atrium and ventricle of the heart.
The central circulatory organ is heart. It is a hollow muscular organ consisting of two halves: the left - arterial and the right - venous. Each half consists of an interconnected atrium and ventricle of the heart.

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

In the lungs, venous blood is saturated with oxygen, becomes arterial and is directed 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 line - the aorta and through its branches, which disintegrate in the tissues of the body to the capillaries, is distributed throughout the body. Having given oxygen to the tissues and taken in carbon dioxide from them, the blood becomes venous. The capillaries, again connecting 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. IN superior vena cava blood is collected from areas and organs of the head and neck, upper limbs and some areas 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 cavae 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 the pulmonary and systemic circulation.

Pulmonary circulation video

Pulmonary 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 the pulmonary veins flowing into the left atrium.

Big circle blood circulation(bodily) starts from the left ventricle of the heart with 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 occurs through two interconnected circulation circles.

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

Along the route lymphatic vessels from organs and parts of the body to trunks and ducts lie numerous lymph nodes related to organs 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, removal of metabolic products, and heat exchange. Represents a closed vasculature, penetrating all organs and tissues, and having a centrally located pumping device- heart.

The circulatory system is connected by numerous neurohumoral connections with the activities of other body systems, serves as an important link in homeostasis and provides blood supply adequate to current local needs. For the first time exact description the mechanism of blood circulation and the importance of the heart are given by the founder of experimental physiology English doctor W. Harvey (1578-1657). In 1628, he published the famous work “An 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.

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

The blood vessels of the body are combined into the systemic and pulmonary circulation. In addition, the coronary circulation is additionally distinguished.

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 cavae flowing into the right atrium. Through the walls of the body's capillaries, the exchange of substances between blood and tissues occurs. Arterial blood gives oxygen to tissues and, saturated with carbon dioxide, turns into venous blood. Typically, an arterial type vessel (arteriole) approaches the capillary network, and a venule emerges from 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, an efferent vessel, also emerges from the glomerulus. A capillary network inserted between two vessels of the same type (arteries) is called arterial miraculous network. Built like a wonderful network capillary network located between the afferent (interlobular) and efferent (central) veins in the liver lobule - venous miraculous network.

2)Pulmonary 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 flowing 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 circle of blood circulation - cordial , includes the vessels of the heart itself to supply blood to the heart muscle. It begins with the left and right coronary arteries, which arise from the initial part of the aorta - the aortic bulb. Flowing through the capillaries, the blood delivers 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.

Just not large number The so-called smallest veins of the heart flow independently, bypassing the coronary sinus, into all chambers of the heart. It should be noted that the heart muscle needs a constant supply of large amounts of oxygen and nutrients, which is ensured by a rich blood supply to the heart. With a heart weight of only 1/125-1/250 of body weight, in coronary arteries 5-10% of all blood ejected into the aorta arrives.

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

Pulmonary circulation - This is the path of blood from the right ventricle to the left atrium.

Venous, with low content oxygen enters the blood right side hearts. Shrinking right ventricle throws it into pulmonary artery. Through the two branches into which the pulmonary artery is divided, this blood flows to light. There, the branches of the pulmonary artery, dividing into smaller and smaller arteries, pass into capillaries, which densely entwine numerous pulmonary vesicles containing air. Passing through the capillaries, the blood is enriched with oxygen. At the same time, carbon dioxide passes from the blood into the air, which fills the lungs. Thus, in the capillaries of the lungs, venous blood is converted to arterial blood. It enters the veins, which, connecting with each other, form four pulmonary veins, which flow into left atrium(Fig. 57, 58).

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

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

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

The blood circulation time 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. At the exit of the aorta and pulmonary artery from the ventricles of the heart, semilunar valves(Fig. 58). They look like pockets placed on internal walls 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, blood cannot return to the heart due to the fact that, flowing into the pockets, it stretches them and they close tightly. Consequently, semilunar valves ensure the movement of blood in one direction - from the ventricles to the arteries.

On this page there is material on the following topics:

• Circulation circles lecture notes

• Report on the topic of the human circulatory system

• Lectures circulatory circles diagram of animals

• Blood circulation - large and small circles of blood circulation - cheat sheet

• The advantage of two circles of blood circulation compared to one

Questions about this material:

The systemic and pulmonary circulations were discovered by Harvey in 1628. Later, scientists from many countries made important discoveries regarding 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 being enriched with ever 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 causes blood to circulate throughout the systemic and pulmonary circulation. This process is continuous, thanks to it absolutely all cells of the body receive oxygen and important nutrients.

The meaning of blood

The systemic and pulmonary 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 nutritional components, including enzymes and hormones, enter the tissues, and metabolic products are removed from the intercellular space. In addition, it is blood that provides constant temperature the human body, protecting the body from pathogenic microbes.

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

Heart

The 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 chest area. Its average weight in an adult 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 pause between them. This takes less than one second. In one minute human heart is reduced at least 70 times. Blood moves through the vessels in a continuous stream, constantly flows through the heart from the small circle to the large circle, carrying oxygen to the organs and tissues and bringing carbon dioxide to the alveoli of the lungs.

Systemic (systemic) circulation

Both the systemic and pulmonary circulations perform the function of gas exchange in the body. When blood returns from the lungs, it is already enriched with oxygen. Next, it needs to be delivered to all tissues and organs. This function is performed by the systemic circulation. It originates in the left ventricle, leading to the tissues blood vessels, 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 emerges from it into large arteries. Getting into the aorta and brachiocephalic trunk, it rushes to the tissues with great speed. One large artery per top part body, and on the second - to the lower one.

The brachiocephalic trunk is a large artery separated from the aorta. It is rich in oxygen blood is flowing up to the head and hands. The second major artery, the aorta, delivers blood to bottom part body, to the legs and tissues of the torso. These two main blood vessels, as mentioned above, are repeatedly divided into smaller capillaries, which permeate organs and tissues in a mesh. These tiny vessels deliver oxygen and nutrients to the intercellular space. From it carbon dioxide and other necessary for the body metabolic products. 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 part of the body unite into the inferior vena cava. And those that go from the upper torso and head - into the superior vena cava. Both of these vessels empty into the right atrium.

Lesser (pulmonary) circulation

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

Anatomical structure of the small circle

Venous, oxygen-poor blood emerges from the right ventricle of the heart. It enters the largest artery of the small circle - the pulmonary trunk. It is divided into two separate vessels (right and left artery). This is very important feature pulmonary circulation. Right artery brings blood to 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 the area where gas exchange occurs thousands of times.

Each tiny alveoli has a blood vessel attached to it. From atmospheric air The blood is separated only by the thinnest wall of the capillary and the lung. 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 occurs. Gas moves according to the principle from higher concentration to lower concentration. For example, if there is very little oxygen in the dark venous blood, then it begins to enter the capillaries from the atmospheric air. But with carbon dioxide, the opposite happens: it passes into the alveoli of the lung, since its concentration is lower there. Then the vessels unite again 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 manages to pass through the small and large circles is called the time of complete blood circulation. This indicator is strictly individual, but on average it takes from 20 to 23 seconds at rest. During muscular activity, for example, during running or jumping, the speed of blood flow increases several times, then a complete circulation of blood in both circles can occur in just 10 seconds, but the body cannot withstand such a pace for a long time.

Cardiac circulation

The systemic and pulmonary circulations ensure 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 flows to all parts and layers of the heart, and then through small veins it collects into the venous coronary sinus. This large vessel opens to the right cardiac atrium with its wide mouth. But some of the small veins directly exit into the cavities of the right ventricle and atrium of the heart. This is how the circulatory system of our body is structured.

Most people do not know how many circulations 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 studied it many centuries ago. There are many scientific works famous scientists on this topic. Around the middle of the 17th century, it was proven that human blood circulates. Further research into 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 humans - this is big and small. They interact with each other because human body holistic.

Circulatory organs

We include:

• vessels.

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

Important! If your limbs become numb or your speech becomes sluggish, you should call as soon as possible. ambulance. Perhaps it's a stroke.

Vessels are important participants in the blood flow process; they, like pipes, transport nutrients and fluid to all organs and tissues. The vessels consist of three layers of tissue. They all perform their important functions.

Circulatory organs interconnected.

Vessel groups

Divided into three groups:

• arteries;
• veins;
• capillaries.

An artery is the largest type of vessels. They are very elastic. The movement of liquid through them occurs at 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 may be disrupted, the pressure may drop, or, on the contrary, increase. Some people's blood pressure regularly rises, a condition called hypertension. There are people with chronically low blood pressure– hypotensive.

Arterial injuries are very dangerous and pose a threat to human life; it is necessary to urgently call an ambulance. It is important to stop the bleeding in time. We need to apply a tourniquet. From damaged arteries blood flows like a fountain.

Capillaries – arise from 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 upper layers skin, they are easily damaged and injured. Damage to capillaries for an ordinary body without disturbances in the circulatory system does not pose a danger and does not require the help of doctors.

Veins are vessels through which blood comes back, ending the cycle. Through the veins, fluid enriched with all the necessary fluids moves back to the heart. useful substances. Veins are medium-thick vessels. Like other vessels, they are elastic. Vein injuries also require medical care, although less dangerous than arterial damage.

Briefly about the blood flow system

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

The blood enters the widest artery in diameter - the aorta, then spreads through other arteries, then through the capillaries and goes to the peripheral tissues and all organs.

The blood is saturated with useful substances, after which it is released into the veins. Through the veins, blood returns to the heart, namely, to the right atrium. This blood flow system is called the bodily system because the vessels supply blood to areas 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! All more people has 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 penetrated by countless capillaries, which are kilometers long. The veins of the systemic circulation complete the cycle.

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

Pulmonary circulation

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

What is a small circle?

The pulmonary circulation includes the following elements:

1. Right ventricle;
2. Left atrium;
3. Lungs;
4. Arteries;
5. Capillaries;
6. Vienna.

Those small vessels, which diverge from the arteries, penetrates the lungs, passing through all the alveoli - these are bubbles with pure. The paradox of the system of this circle - venous blood is pumped through the arteries, and arterial blood flows through the veins.

Strong emotions always lead to increased blood 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. 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 blood poorly supplies distant areas, for example, it does not flow to the limbs. This leads to discomfort, sometimes to serious problems with health. For example, Reine's syndrome is associated precisely with the lack of blood flow to the fingers. The simplest thing that bothers people with poor blood flow is constantly cold extremities. They always suffer from this nerve endings, lacking nutrients.

Heartbeat

It’s interesting that when we’re at rest, we don’t notice how our heart beats. Moreover, it does not bring us discomfort. And after physical activity, we hear this organ knocking. He pumps blood more intensely and quickly.

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

And for those who physical activity are allowed, you need to remember that the heart is a muscle, which means it requires constant training. Great for work cardiovascular system charging affects. It gives you a boost of energy for the whole day. You can sign up for gym or study at home. Swimming is great for training your heart.

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

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

In our body blood continuously moving along closed system 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 blood movement is the heart.

The circulatory system consists of hearts And vessels. There are three types of vessels: arteries, veins, capillaries.

Heart- a hollow muscular organ (weight about 300 grams) approximately the size of a fist, located in chest cavity left. The heart is surrounded by a pericardial sac formed by connective tissue. Between the heart and the pericardial sac there is a fluid that reduces friction. Humans have a four-chambered heart. The transverse septum divides it into left and right half, each of which is separated by valves, neither the atrium nor the 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, as it makes great job, pushing blood into the systemic circulation. At the border between the atria and ventricles there are leaflet valves that prevent the reverse flow of blood.

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

Strong tendon threads are attached to the valve leaflets on the ventricular side. This design prevents blood from moving from the ventricles into the atrium during ventricular contraction. At the base pulmonary artery and the aorta contain semilunar valves that prevent blood from flowing from the arteries back into the ventricles.

The right atrium receives venous blood from the systemic circulation, and the left atrium receives arterial blood from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, the left ventricle supplies arterial blood from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, its walls are approximately three times thicker than the walls of the right ventricle. Cardiac muscle is a special type of striated muscle in which the muscle fibers grow together at their ends and form a complex network. This structure of the muscle increases its strength and speeds up the passage nerve impulse(the whole muscle reacts simultaneously). Cardiac muscle is different from skeletal muscles the ability to contract rhythmically, responding to impulses arising in the heart itself. This phenomenon is called automaticity.

Arteries- vessels through which blood moves from the heart. Arteries are thick-walled vessels middle layer which are represented by elastic and smooth muscles, therefore, the arteries are able to withstand significant blood pressure and not rupture, but only stretch.

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

Vienna– vessels, blood bearers to the heart. The vein walls also have valves that prevent blood from flowing back.

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

Blood through the veins does not flow entirely passively; the surrounding muscles perform pulsating movements and drive blood through the vessels to the heart. Capillaries are the smallest blood vessels through which blood plasma is exchanged with tissue fluid nutrients. 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 metabolism 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

Pulmonary circulation– 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 through the pulmonary veins after gas exchange in the lungs - arterial blood.

The pattern of blood movement in circulatory circles 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.

367. Blood circulation diagram (according to Kishsh, Sentagotai).

1 - general carotid artery;

2 - aortic arch;

8 - superior mesenteric artery;

Pulmonary circulation (pulmonary)

Venous blood from the right atrium passes through the right atrioventricular orifice into the right ventricle, which contracts and pushes 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 surrounding each alveolus. After red blood cells release carbon dioxide and enrich them with oxygen, venous blood turns into arterial blood. Arterial blood flows through four pulmonary veins (there are two veins in each lung) into the left atrium, then passes through the left atrioventricular orifice into the left ventricle. The systemic circulation begins from the left ventricle.

Systemic circulation

Arterial blood from the left ventricle is ejected into the aorta during its contraction. The aorta splits into arteries that supply blood to the limbs and torso. All internal organs and ending with capillaries. Nutrients, water, salts and oxygen are released from the blood capillaries into the tissues, metabolic products and carbon dioxide are resorbed. The capillaries gather into venules, where the venous system of vessels 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 collects through small veins into the venous coronary sinus. This vessel opens with a wide mouth into the right atrium. Some of the small veins of the heart wall directly open into the cavity of the right atrium and ventricle of the heart.

Non-existent page

The page you are reading does not exist.

Sure ways to get nowhere:

• write Rudz.yandex.ru instead help.yandex.ru (download and install Punto Switcher if you don’t want to make that mistake again)
• write i ne x.html, i dn ex.html or index. htm instead of index.html

If you think we brought you here on purpose by posting an incorrect link, please send us the link to [email protected].

Circulatory and lymphatic systems

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

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

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

The movement of blood in the human body is called blood circulation. The continuity of blood flow is ensured 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. Left and right side the hearts are separated by a continuous muscular septum. The weight of an adult human heart is approximately 300 g.

Human life and health largely depend on normal operation his heart. It pumps blood through the vessels of the body, maintaining the viability of all organs and tissues. Evolutionary structure of the human heart - diagram, blood circulation, automaticity of contraction and relaxation cycles muscle cells walls, the operation of 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 through which the body is saturated with oxygen and nutrients is anatomical education cone-shaped, located in chest, mostly on the left. Inside the organ there is a cavity divided into four unequal parts by partitions - these are two atria and two ventricles. The former collect blood from the veins flowing into them, and the latter push it into the arteries emanating from them. Normally, the right side of the heart (atrium and ventricle) contains oxygen-poor blood, and the left side contains oxygenated blood.

Atria

Right (RH). Has a smooth surface, volume 100-180 ml, including additional education- right ear. Wall thickness 2-3 mm. Vessels flow into the RA:

• superior vena cava,
• cardiac veins - through the coronary sinus and pinpoint openings 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 LA receives blood from the four pulmonary veins.

Separates the atria interatrial septum(MPP), which normally does not have any holes in adults. They communicate with the cavities of the corresponding ventricles through openings equipped with valves. On the right is the tricuspid tricuspid, on the left is the bicuspid mitral.

Ventricles

The right (RV) is cone-shaped, the base facing upward. Wall thickness up to 5 mm. Inner surface in the upper part it 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, through the chordae tendineae, keep the tricuspid valve leaflets from bending into the atrium cavity. The chordae also extend directly from the muscular layer of the wall. At the base of the ventricle there are two openings with valves:

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

Left (LV). This part 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,
• exit to the aorta with the tricuspid aortic.

Muscle cords at the apex of the heart and papillary muscles supporting the valves mitral valve here are more powerful than similar structures in the pancreas.

The membranes of the heart

To protect and ensure the movements of the heart in the chest cavity, it is surrounded by a cardiac lining - the pericardium. There are three layers directly in the heart wall - epicardium, endocardium, and myocardium.

• The pericardium is called the cardiac sac; it is loosely adjacent to the heart, its outer layer is in contact with neighboring organs, and the inner layer is the outer layer of the heart wall - the epicardium. Composition: connective tissue. In order for the heart to glide better, a small amount of fluid is normally present in the pericardial cavity.
• The epicardium also has a connective tissue base; accumulations of fat are observed in the apex and along the coronary grooves, where the vessels are located. In other places, the epicardium is firmly connected to the muscle fibers of the main layer.
• The myocardium makes up the main thickness of the wall, especially in the most loaded area - the left ventricle. Arranged in several layers, muscle fibers run both longitudinally and in a circle, ensuring uniform contraction. The myocardium forms trabeculae at the apex of both ventricles and papillary muscles, from which chordae tendineae 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 its length from the myocardium. In the upper part, called membranous, its base is connective tissue.
• Endocardium is a sheet that covers everything internal structures hearts. It has three layers, 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. The endocardium also contains connective tissue, collagen fibers, and smooth muscle cells.

All heart valves are formed from endocardial folds.

Human heart structure and functions

Pumping blood into the heart vascular bed is ensured by the features of its structure:

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

How does the cardiac cycle work?

It consists of three successive 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 pulmonary and aortic valves are closed.
• Atrial systole occurs when the pacemaker is automatically excited in sinus node atria. At the end of this phase, the valves between the ventricles and atria close.
• Ventricular systole occurs in two stages - isometric tension and expulsion of blood into the vessels.
• The period of tension begins with asynchronous contraction of the muscle fibers of the ventricles until the complete closure of the mitral and tricuspid valves. Then tension begins to increase in the isolated ventricles and pressure increases.
• When it gets higher than arterial vessels, the expulsion period is initiated - the valves open, releasing blood into the arteries. At this time, the muscle fibers of the walls of the ventricles contract intensively.
• Then the pressure in the ventricles decreases, the arterial valves close, which corresponds to the beginning of diastole. During complete relaxation the atrioventricular valves open.

Conduction system, its structure and heart function

The conduction system of the heart ensures myocardial contraction. Its main feature is the automaticity of cells. They are capable of self-excitation in a certain rhythm, depending on the electrical processes accompanying cardiac activity.

The conduction system includes the sinus and atrioventricular nodes, the underlying bundle and branches of His, and Purkinje fibers.

• Sinus node. Normally generates the initial impulse. Located at the mouth of both vena cava. From it, excitation passes to the atria and is transmitted to the atrioventricular (AV) node.
• The atrioventricular node distributes the impulse to the ventricles.
• The bundle of His is a conducting “bridge” located in interventricular septum, there it is divided into right and left leg, transmitting excitation to the ventricles.
• Purkinje fibers are the terminal section of the conduction system. They are located near the endocardium and come into direct contact with the myocardium, causing it to contract.

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

The task of the circulatory system, the main center of which is the heart, is the delivery of oxygen, nutritional and bioactive components to the tissues of the body and the elimination of metabolic products. For this purpose, the system provides a special mechanism - blood moves through the circulation circles - 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 systemic circulatory system.

Big circle

From the left ventricle in systole, arterial blood travels through the aorta and then through vessels of different diameters to the various bodies, giving them oxygen, transferring nutritional and bioactive elements. In small tissue capillaries, blood turns into venous blood, as it is saturated with metabolic products and carbon dioxide. It flows through the vein system to the heart, filling its right sections.

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