© Author: Sasikina Oksana Yuryevna, cardiologist, especially for V. Visidofo.ru (about the authors)
In the human body, the circulatory system is arranged so as to fully respond to its internal needs. An important role in the promotion of blood plays the presence of a closed system in which arterial and venous blood flows are separated. And it is carried out using the presence of circles of blood circulation.
In the past, when scientists did not yet have informative devices that could study physiological processes on a living organism, the greatest science figures were forced to search for anatomical features from the corpses. Naturally, the deceased man does not cut the heart, so some nuances had to occur independently, and sometimes simply fantasize. So, in the second century of our era Claudius Galen, studying Hippocratic It assumed that the arteries contain in their enlighten the air instead of blood. Throughout further centuries, there were many attempts to combine and tie together the existing anatomical data from the position of physiology. All scientists knew and understood how the blood circulation system was arranged, but how does it work?
Colossal contribution to the systematization of data on the work of the heart made scientists Miguel Servers and William Garvey in the 16th century. GARVEY, Scientist who first described the big and small circles of blood circulation , in 1616 I defined the presence of two circles, but how arterial and venous beds are connected with each other, he could not explain in his writings. And only afterwards, in the 17th century, Marchello Malpigi, One of the first to use a microscope in his practice, discovered and described the presence of the smallest, invisible capillaries, who serve as a link in circles of blood circulation.
Phylogenesis, or evolution of circles of blood circulation
Due to the fact that, as the animals are evolution, the animals of the vertebrates became increasingly progressive in anatomy-physiological relation, they needed a complex device and a cardiovascular system. So, for a faster movement of the liquid internal environment in the organism of the vertebral animal, there was a closed blood circulation system. Compared to other classes of the animal kingdom (for example, with arthropod or with worms), the chords appear for a closed vascular system. And if the lancing age, for example, there is no heart, but there is an abdominal and spinal aorta, then fish, amphibians (amphibians), reptiles (reptiles) appear two- and three-chamber heart, respectively, and in birds and mammals - a four-chamber heart, whose feature It is the focus in it two circles of blood circulation that are not mixed with each other.
Thus, the presence of birds, mammals and humans, in particular, two split circles of blood circulation is nothing more than the evolution of the circulatory system necessary for better adaptation to the environmental conditions.
Anatomical features of circles of blood circulation
Circulation circles are a combination of blood vessels, which is a closed system for admission to internal oxygen organs and nutrients through gas exchange and sharing nutrients, as well as to remove carbon dioxide cells and other metabolic products. For the human body, two circles are characterized - systemic, or large circle, as well as a pulmonary, also called small circle.
Video: circulation circles, mini lecture and animation
Big circle circulation
The main function of the Big Circle is to ensure gas exchange in all internal organs, except for the lungs. It begins in the left ventricle cavity; It is represented by the aortic and its branches, the arterial channel of the liver, kidneys, brain, skeletal muscles and other organs. Further, this circle continues the capillary network and the venous channel of the listed bodies; And through the imposition of a hollow vein into the cavity of the right atrium ends in the latter.
So, as already mentioned, the beginning of a large circle is the left ventricular cavity. This is the arterial blood flow containing most of the oxygen, rather than carbon dioxide. This flow into the left ventricle falls directly from the bloodary system of the lungs, that is, from a small circle. The arterial flow from the left ventricle through the aortic valve is pushing into the largest main vessel - in the aorta. Aorta is figuratively compared with a peculiar tree that has many branches, because artery from the internal organs (to the liver, kidneys, gastrointestinal tract, to the brain - through the system of sleepy arteries, to skeletal muscles, to subcutaneous fatty fiber, etc.). Organ arteries, also having numerous branching and wearing appropriate name anatomy, carry oxygen into each organ.
In the tissues of internal organs, arterial vessels are divided into vessels of increasing and smaller diameter, and as a result, a capillary network is formed. Capillaries are the above-hand vessels, practically having a medium-sized muscular layer, and represented by the inner shell - intimate lined with endothelial cells. The lumens between these cells on the microscopic level are so large compared to other vessels, which make it possible to freely penetrate proteins, gases and even uniform elements in the intercellular fluid of surrounding tissues. Thus, there is an intensive gas exchange and exchange of other substances between the capillary with arterial blood and liquid intercellular medium in one or another organ. Oxygen penetrates from the capillary, and carbon dioxide, as a cell of cell metabolism - in capillary. The cell stage of breathing is carried out.
After a greater amount of oxygen passed in the tissue, and all carbon dioxide was removed from the tissue, the blood becomes venous. All gas exchange is carried out with each new influx of blood, and for the period of time, while it moves around the capillary towards Venory - the vascular collecting venous blood. That is, with each cardiac cycle in one or another site of the body, oxygen flows into the tissue and removing carbon dioxide from them.
These venules are combined into veins of bigger, and venous channel is formed. Vienna, similar to the arteries, carry those names in which organ they are located (renal, brain, etc.). From large venous trunks, inflows of the upper and lower hollow veins are formed, and the latter then fall into the right atrium.
Features of the blood flow in the Big Circle Organs
Some of the internal organs have their own characteristics. For example, in the liver, there is not only a hepatic vein, "relating" venous flow from it, but also a gorgeous, which is the opposite, brings blood to the hepatic cloth, where blood purification is performed, and only then the blood is going to the hepatic veins tributaries to get To a large circle. Right vein brings blood from the stomach and intestines, so everything that man ate or drank should pass a kind of "cleaning" in the liver.
In addition to the liver, certain nuances exist in other organs, for example, in the tissues of pituitary and kidney. Thus, in the pituitary gland, the presence of the so-called "wonderful" capillary network is noted, because the arteries bringing blood to the pituitary gland from the hypothalamus are divided into capillaries, which are then collected in Vienuly. Venules, after the blood with molecules of release hormones are assembled, is again divided into capillaries, and then veins relating to blood from the pituitary gland are already formed. In the kidneys, the arterial network is divided twice on the capillaries, which is associated with the processes of isolation and reverse absorption in kidney cells - in nephron.
Small circle circulation
Its function is the implementation of gas exchange processes in the pulmonary tissue in order to saturate the "exhaust" venous blood oxygen molecules. It begins in the cavity of the right ventricle, where from the right-atrial chamber (from the "end point" of a large circle) comes venous blood flow with an extremely minor amount of oxygen and with a large content of carbon dioxide. This blood through the pulmonary artery valve is moving into one of the large vessels, called the pulmonary barrel. Next, the venous stream moves through the arterial bed in the pulmonary fabric, which also disintegrates the network from the capillaries. By analogy with the capillaries in other tissues, gas exchange is carried out in them, but the oxygen molecules are received in the clearance of the capillary, and carbon dioxide penetrates into alveolocytes (alveolo cells). In the alveoli, with each respiratory act, air from the environment enters, from which oxygen through the cell membranes penetrates the blood plasma. With exhaled air, with an exhalation, the carbon dioxide entered alveoli is displayed outside.
After saturation by molecules 2The blood acquires the properties of arterial, proceeds through Venulaula and ultimately gets to the pulmonary veins. The latter four or five pieces are opened in the left atrium cavity. As a result, a venous blood flow is flowing through the right half of the heart, and through the left half - arterial; And in the norm, these streams should not be mixed.
In the lung tissue there is a double capillary network. Using the first, gas exchange processes are carried out in order to enrich the venous flow with oxygen molecules (the relationship directly with the small circle), and in the second is powering the lung tissue with oxygen and nutrients (relationship with a large circuit).
Additional circles of blood circulation
These concepts are made to allocate the blood supply to individual bodies. For example, to the heart that more than others need oxygen, the arterial influx is carried out from the aorta branches at its very beginning, which were called the right and left coronary (corneous) arteries. In the capillaries of myocardium there is an intense gas exchange, and the venous outflow is carried out in coronary veins. The latter are going to the coronary sinus, which opens directly into the right-atrial chamber. This way is carried out Cardiac, or coronary circle of blood circulation.
Corn (coronary) circle of blood circulation in the heart
Willisyev Krug. It is a closed arterial network of brain arteries. The brain circle provides additional blood supply to the brain in violation of cerebral blood flow by other arteries. It protects such an important organ from lack of oxygen, or hypoxia. The brain circle of blood circulation is represented by the initial segment of the anterior brain artery, the initial segment of the rear brain artery, the front and rear connecting arteries, internal carotid arteries.
Willisye circle in the brain (classic version of the structure)
Placentational circle of blood circulation It functions only during the tooling of the fetus of the woman and performs the function of "breathing" in the child. The placenta is formed, starting with 3-6 weeks of pregnancy, and begins to function in full force from the 12th week. Due to the fact that light fetus do not work, the flow of oxygen in its blood is carried out by means of the flow of arterial blood in the umbilical vein of the child.
blood circulation before birth
Thus, the entire human circulatory system can be divided into separate interconnected areas that perform their functions. The correct functioning of such sites, or circles of blood circulation, is the key to healthy work of the heart, vessels and the whole organism as a whole.
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From previous articles, you already know the composition of the blood and structure of the heart. Obviously, all the functions of blood performs only due to its constant circulation, which is carried out through the work of the heart. The work of the heart resembles a pump that injected blood into the vessels in which the blood flows to internal organs and tissues.
The circulatory system consists of a large and small (pulmonary) circles of blood circulation, which we will discuss in detail.
I described them to William Garvey, an English doctor, in 1628.
Big circle circulation (BKK)
This circle circulation is used to deliver oxygen and nutrients to all organs. It begins emerging from
The left ventricle of the aorta is the largest vessel that is consistently branched on artery, arterioles and capillaries.
Opened BKK and understood the value of circles of blood circulation, famous English scientist, doctor William Garvey.
The wall of the capillaries is single-layer, therefore, gas exchanges occurs through it with the surrounding tissues, which, besides, it receives nutrients. In the tissues, breathing occurs during which proteins, fats, carbohydrates are oxidized. As a result in cells
Carbon dioxide and metabolic products (urea) are formed, which are also highlighted in capillaries.
Venous blood is going to Vienna, returning to the heart through the largest - upper and lower hollow veins, which
Plots in the right atrium. Thus, BKK begins in the left ventricle and ends in the right atrium.
Blood passes BKK for 23-27 seconds. According to the arteries of the BCC, arterial blood flows, and on Viennes - venous. The main function of this
The circle of blood circulation is to provide all organs and tissues of the body with oxygen and nutrients. In BKK high vessels
blood pressure (relative to a small circle of blood circulation).
Small circle circulation (pulmonary)
Let me remind you that BKK ends in the right of atrium, which contains venous blood. Small circle of blood circulation (ICC) begins In the next chamber of the heart - the right ventricle. From here, venous blood enters the pulmonary trunk, which is divided into two pulmonary arteries. .
The right and left pulmonary arteries with venous blood are directed to the corresponding light, where they are branched to the capillaries,
Small circle circulation
Fallen alveoli. A gas exchange occurs in capillaries, as a result of which oxygen enters blood and is connected to hemoglobin, and carbon dioxide diffuses into the alveolar air. Oxygen-enriched arterial blood is assembled in Veneules, which are then merged into pulmonary veins. Little Vienna with arterial blood flows into the left atrium, where the ICC ends. From the left atrium blood comes In the left ventricle - the place of the beginning of the BKK. Thus, two circles circulation are closed. ICC Blood passes in 4-5 seconds. The main function is in saturation of venous blood oxygen, as a result of which it becomes arterial rich in oxygen. As you noticed, venous blood flows in the ICC in the ICC, and on the veins - arterial blood. Arterial pressure Here is lower than BKK. Interesting Facts
On average, each minute, the human heart pumped about 5 liters, for 70 years of life - 220 million liters of blood. In one day, the heart of a person makes about 100 thousand shots, in a lifetime - 2.5 billion strikes. © Bellevich Yuri Sergeevich 2018-2021 This article was written by Bellevich Yuri Sergeyevich and is his intellectual property. Copy, distribution (including by copying to other sites and resources on the Internet) or any other use of information and objects Without prior consent, the copyright holder is prosecuted. For the materials of the article and the permission of their use,
Please refer to
Big circle circulation
Bellevich Yury Blood moves along two closed vessel systems connected to the heart, - small and large circles of blood circulation. Blood circulation for a large circulation of blood circulation occurs approximately for \ (20 \) seconds, in a small circle - in \ (5 \) times faster. Small (easy) circle of blood circulationClies with oxygen saturation. Onnomed OT Right ventricle heart . From the right ventricle, blood is pushed in Easy artery. . According to this vessel from the heart flows deoxygenated blood containing little oxygen.
Light artery is divided into two artery: left and right light. In the lung artery branch on the vessels of an all smaller diameter until the capillaries. Venous blood passes through the capillaries of the lungs, gives carbon dioxide and is saturated with oxygen, i.e. it becomes arterial .
. The capillaries are then merged into larger vessels that form light veins. On the light veins arterial blood gets first In the left atrium And then to the left ventricle. From the left ventricle, it returns to a large circle of blood circulation. Watch the video. Big circle of blood circulation begins from left ventricle .
Please refer to
The largest arteries -
. It is large from her large
- Rising artery
- (Blood bearing to the head and upper limbs) and
- Downward arteries
- (Blood bearing to all body bodies, including the heart).
- The arteries are gradually branched by forming a network of capillaries in the organs and tissues, in which substances between blood and tissues are met. Giving up with tissues oxygen and nutrients, blood takes the exchange and carbon dioxide products and becomes
- Venous blood returns to the heart on two large veins: from head and hands -
Upper vena hollow
, and from the bottom of the body -
(Blood bearing to the head and upper limbs) and
Lower Farm Vienna
. Both veins of Vpadayv
(Blood bearing to all body bodies, including the heart).
Building system structure
- A heart
The arteries are gradually branched by forming a network of capillaries in the organs and tissues, in which substances between blood and tissues are met. Giving up with tissues oxygen and nutrients, blood takes the exchange and carbon dioxide products and becomes
System Features in different periods of life Cardiovascular human system (blood-based - outdated name) is a complex of organs that provide the supply of all parts of the body (in a slight exception) necessary substances and removing life products. It is the cardiovascular system that provides all parts of the body with necessary oxygen, and therefore is the basis of life. There is no blood circulation only in some organs: crystal eye, hair, nail, enamel and dentin tooth. In the cardiovascular system, two components are distinguished: it is actually a complex of blood circulation organs and a lymphatic system. Traditionally, they are considered separately. But, despite their difference, they perform a range of joint functions, and also have the overall origin and plan of the structure. The anatomy of the circulatory system implies its separation by 3 components. They differ significantly in the structure, but in functionality represent a single integer. These are the following organs:
A peculiar pump pumping blood according to vessels. This is a muscular fibrous hollow organ. Located in the cavity of the chest. Histology of the body distinguishes several tissues. The most important and significant size is muscular. Inside and outside the organ is covered with fibrous fabric. The cavity of the heart is separated by partitions on 4 cameras: atrium and ventricles.
A healthy person has heart rate from 55 to 85 shots per minute. It comes throughout life. So, for 70 years there is 2.6 billion abbreviations. At the same time, the heart pumped about 155 million liters of blood. The body weight ranges from 250 to 350 g. Reducing the heart cameras is called systole, and relaxation is diastole.
- These are long hollow tubes. They depart from the heart and, repeatedly branched, go to all parts of the body. Immediately at the exit from its cavities, the vessels have the maximum diameter, which as it becomes less. Distinguish several types of vessels:
- Artery. They carry blood from the heart to the periphery. The very largest of them is aorta. It comes out of the left ventricle and carries blood to all vessels, except for the lungs. The branches of the aortes are divided repeatedly and penetrate all the fabrics. Pulmonary artery carries blood to the easy. She comes from the right ventricle.
- Vessels of the microcirculatory bed. These arterioles, capillaries and Venules are the smallest vessels. The blood of arterioles is in the thickness of the fabrics of internal organs and skin. They are branched on the capillaries that carry out the exchange of gases and other substances. After that, blood is going to Vienuly and flows further.
Vienna - vessels carrying blood to heart. They are formed with an increase in the diameter of Wesull and their multiple fusion. The largest vessels of this type are lower and upper hollow veins. They are directly falling into the heart.
A peculiar body fabric, liquid, consists of two main components:
Venous blood returns to the heart on two large veins: from head and hands -
- Plasma - a liquid part of the blood in which all uniform elements are located. Percentage ratio - 1: 1. Plasma is a turbid yellowish liquid. It contains a large amount of protein molecules, carbohydrates, lipids, various organic compounds and electrolytes.
- The uniform elements of blood include: erythrocytes, leukocytes and thrombocytes. They are formed in the red bone marrow and circulate through the vessels all life of a person. Only leukocytes under certain circumstances (inflammation, the introduction of an alien organism or matter) can pass through the vascular wall in the intercellular space.
- The adult has 2.5-7.5 (depending on the mass) of blood ml. The newborn is from 200 to 450 ml. The vessels and the work of the heart provide the most important indicator of the circulatory system - arterial pressure. It ranges from 90 mm Hg. Up to 139 mm Hg.st. For systolic and 60-90 - for diastolic.
All vessels form two closed circles: big and small.
This ensures uninterrupted simultaneous supply of organism oxygen, as well as gas exchange in the lungs. Each circulation circle begins from the heart and ends there.
Small goes from the right ventricle on the pulmonary artery in the lungs. Here it is branching several times. The blood vessels form a thick capillary network around all bronchi and alveoli. The gas exchange occurs through them. Blood rich in carbon dioxide gives it to the cavity of the alveoli, and in return gets oxygen. After that, the capillaries are consistently gather in two veins and go to the left atrium. The small circle of blood circulation ends. Blood goes to the left ventricle.
A large circle of blood circulation begins from the left ventricle. During systole, the blood goes to the aorta, from which many vessels (arteries) are branched. They are divided several times until it turns into capillaries supplying the whole organism with blood - from the skin to the nervous system. Here is the exchange of gases and nutrients. After that, blood is consistently assembled into two large veins going to the right atrium. The big circle ends. Blood from the right atrium falls into the left ventricle, and everything begins again.
Cardiovascular system performs a number of essential functions in the body:
Power supply and supply of oxygen.
Big circle circulation Maintaining homeostasis (constancy of conditions within the whole organism).
The supply of oxygen and nutrients is as follows: the blood and its components (erythrocytes, proteins and plasma) deliver oxygen, carbohydrates, fats, vitamins and trace elements to any cell. At the same time, they take carbon dioxide and harmful waste (produced by vital activity).
Small circle circulation The constant conditions in the body are provided by the bloodstream itself and its components (erythrocytes, plasma and proteins). They not only perform carriers, but also regulate the most important indicators of homeostasis: pH, body temperature, humidity level, amount of water in cells and intercellular space.
Lymphocytes play direct protective function. These cells can neutralize and destroy alien maturity (microorganisms and organic matter). Cardiovascular system provides them to quick delivery in any corner of the body.
During the intrauterine development, the cardiovascular system has a number of features.
Installed a message between the atriums ("Oval Window"). It provides a direct blood transition between them.
Blood from the pulmonary vein moves to the aorta by special open duct (battles duct).
Blood is enriched with oxygen and nutrients in the placenta. From there on the umbilical vein, it goes into the cavity of the belly through the hole of the same name. Then the vessel flows into the hepatic vein. From where, passing through the organ, the blood enters the lower hollow vein, to the runway flows into the right atrium. From there, almost all the blood goes to the left. Only her small part is thrown into the right ventricle, and then into the lung vein. Blood from the organs is going to the umbilical artery that go to the placenta. Here it is again enriched with oxygen, it receives nutrients. At the same time, carbon dioxide and toddler exchange products go to the blood of the mother, the body that displays them. Cardiovascular system in children after birth undergo a number of changes. Batalov duct and oval hole overgrow. Basic vessels are engaged and turn into a round ligament of the liver. Begins to function a small circle of blood circulation. By 5-7 days (maximum - 14), the cardiovascular system acquires those traits that are preserved in humans throughout life. Only the number of circulating blood in different periods changes. Initially, it increases and 25-27 reaches a maximum. Only after 40 years the volume of blood begins to decline somewhat, and after 60-65 years remains within 6-7% of the body weight.
- In some periods of life, the number of circulating blood increases or decreases temporarily. Thus, during pregnancy, the volume of plasma becomes more source by 10%. After childbirth, it decreases to the norm for 3-4 weeks. During starvation and unforeseen physical exertion, the amount of plasma becomes less than 5-7%.
- The continuous movement of blood along the closed system of the cavities of the heart and blood vessels is called blood circulation. The blood circulation system helps to ensure all the vital functions of the body.
- Blood movement on blood vessels occurs due to heart cuts. The person distinguishes a large and small circles of blood circulation.
Big and Small Circulation Circles It begins the largest arteries - aorta. Due to the reduction in the left ventricle of the heart, the blood is thrown into the aorta, which is then decayed on artery, arterioles supplying the upper and lower limbs, head, torso, all internal organs and ending with capillaries.
Passing over the capillars, blood gives the tissues oxygen, nutrients and takes dissimilating products. From the capillaries, blood is collected in small veins, which, merging and increasing its cross section, form upper and lower hollow veins. 2.
The big cool blood circulation in the right atrium ends. In all arteries of a large circle of blood circulation, arterial blood flows, in veins - venous.
It begins in the right ventricle, where the venous blood comes from the right atrium. The right ventricle, shrinking, pushes the blood to the pulmonary trunk, which is divided into two pulmonary arteries that carry blood to the right and left light. In the lungs, they are divided into capillaries surrounding each alveoli. In alveoli, blood gives carbon dioxide and is saturated with oxygen.
According to the four pulmonary veins (in every light two veins), blood saturated with oxygen enters the left atrium (where the small circle of blood circulation ends), and then in the left ventricle. Thus, in the arteries of a small circle of blood circulation flows venous blood, and in its veins - arterial. The pattern of blood flow through circles of blood circulation was opened by an English anatom and a doctor of U.garvei in 1628.
Blood vessels: arteries, capillaries and veins