The heart is the most important organ in the human body. Scientists from all fields of knowledge are engaged in its study. People are trying to find a way to prolong the he alth of the heart muscle, improve its performance. Knowledge of the anatomy, physiology and pathology of the heart, even for the layman, will help to better understand the processes that occur in our body. How many chambers are in the human heart? Where do circulatory circles begin and end? How is the heart supplied with blood? All these questions can be answered in this article.
Anatomy of the heart
The heart is a three-layer bag. Outside, it is covered by the pericardium (a protective bag), behind it are the myocardium (a contracting muscle) and the endocardium (a thin mucous plate that covers the inside of the chamber of the heart).
In the human body, the organ is located in the center of the chest. It is slightly off the vertical axis, so most of it is on the left. The heart consists of chambers - four cavities that communicate with each other using valves. These are two atria (right and left) and two ventricles, which are located under them. Between themselves, they are separated by valves, whichprevent backflow of blood.
The walls of the ventricles are thicker than the walls of the atria, and they are larger in volume, since their job is to push blood into the vasculature, while the atria passively receive fluid.
Features of the structure of the heart in the fetus and newborn
How many chambers are in the heart of a person who has not yet been born? There are also four of them, but the atria communicate with each other through an oval hole in the septum. At the stage of embryogenesis, it is necessary for the discharge of blood from the right parts of the heart to the left, since there is no pulmonary circulation yet - the lungs are not straightened. But blood still enters the developing respiratory organs, and it goes directly from the aorta through the ductus arteriosus.
The chambers of the fetal heart are thinner and much smaller than those of an adult, and only thirty percent of the total myocardial mass is reduced. Its functions are closely related to the entry of glucose into the maternal bloodstream, as the child's heart muscle uses it as a nutrient substrate.
Blood supply and circulation
The blood supply to the myocardium occurs from the moment of systole, when blood under pressure enters the main vessels. The vessels of the chambers of the heart are located in the thickness of the myocardium. The large coronary arteries arise directly from the aorta, and when the ventricles contract, some of the blood leaves to feed the heart. If this mechanism is disrupted at any stage, myocardial infarction occurs.
Human heart chambersperform a pumping function. From the point of view of physics, they simply pump liquid in a vicious circle. The pressure that is created in the cavity of the left ventricle, during its contraction, the blood will accelerate so that it reaches even the smallest capillaries.
Two circles of blood circulation are known:
- large, designed to nourish body tissues;
- small, functioning exclusively in the lungs and supporting gas exchange.
Each chamber of the heart has afferent and efferent vessels. Where does blood enter the systemic circulation? From the left atrium, fluid enters the left ventricle and fills it, thereby increasing the pressure in the cavity. When it reaches 120 mm of water, the semilunar valve that separates the ventricle from the aorta opens and blood enters the systemic circulation. After all the capillaries are filled, the process of cellular respiration and nutrition takes place. Then, through the venous system, the blood flows back to the heart, or rather, to the right atrium. The superior and inferior vena cava approach it, collecting blood from the whole body. When enough fluid accumulates, it rushes into the right ventricle.
The pulmonary circulation begins from it. Saturated with carbon dioxide and metabolic products, the blood enters the pulmonary trunk. And from there into the arteries and capillaries of the lungs. Through the hematoalveolar barrier, gas exchange with the external environment occurs. Already rich in oxygen, the blood returns to the left atrium to enter the systemic circulation again. The whole cycle takesless than thirty seconds.
Work cycle
In order for the body to constantly receive the necessary nutrients and oxygen, the chambers of the heart must work very smoothly. There is a course of action determined by nature.
1. Systole is the contraction of the ventricles. It is divided into several periods:
- Tension: individual myofibrils contract, the pressure in the cavity rises, the valve between the atria and ventricles closes. Due to the simultaneous contraction of all muscle fibers, the configuration of the cavity changes, the pressure rises to 120 mm of water column.
- Exile: semilunar valves open - blood enters the aorta and pulmonary trunk. The pressure in the ventricles and atria gradually equalizes, and the blood completely leaves the lower chambers of the heart.
2. Diastole is the relaxation of the myocardium and the period of passive blood intake. The upper chambers of the heart communicate with the afferent vessels and accumulate a certain amount of blood. The atrioventricular valves then open and fluid flows into the ventricles.
Diagnosis of disorders in the structure and function of the heart
- Electrocardiography. This is the registration of electronic phenomena that accompany muscle contractions. The chambers of the heart are made up of cardiomyocytes, which generate an action potential before each contraction. It is he who is fixed by the electrons superimposed on the chest. Thanks to this visualization method, it is possible to detect gross violations in the work of the heart, its organic or functional damage (heart attack, defect, expansion of cavities, the presence ofadditional abbreviations).
- Auscultation. Listening to the beat of the heart was the most ancient way to identify his diseases. Experienced physicians using this method alone can detect most structural and functional pathologies.
- Ultrasound. Allows you to see the structure of the chambers of the heart, the distribution of blood, the presence of defects in the muscle and many other nuances that help make a diagnosis. The method is based on the fact that ultrasonic waves are reflected from solid substances (bones, muscles, organ parenchyma) and freely pass through the liquid.
Pathologies of the heart
As in any other organ, pathological changes accumulate in the heart with age, which provoke the development of diseases. Even with a he althy lifestyle and constant he alth monitoring, no one is immune from problems with the cardiovascular system. Pathological processes can be associated with a violation of the function or structure of an organ, capture one, two or three of its membranes.
The following nosological forms of pathologies are distinguished:
- violations of rhythm and electrical conduction of the heart (extrasystole, blockade, fibrillation);
- inflammatory diseases: endo-, myo-, peri-, pancarditis;
- acquired or congenital malformations;
- hypertension and ischemic lesions;
- vascular lesions;
- pathological changes in the wall of the myocardium.
The last type of pathology needs to be analyzed in more detail, since it has a directrelation to the chambers of the heart.
Dilation of heart chambers
Over time, the myocardium, which forms the walls of the chambers of the heart, can undergo pathological changes such as excessive stretching or thickening. This is due to the breakdown of compensatory mechanisms that allow the body to work with significant overloads (hypertension, increased blood volume or its thickening).
The causes of dilated cardiomyopathy are:
- Infections of various etiologies (fungi, virus, bacteria, parasites).
- Toxins (alcohol, drugs, heavy metals).
- Systemic connective tissue diseases (rheumatism, systemic lupus erythematosus).
- Tumor of the adrenal glands.
- Hereditary muscular dystrophy.
- Presence of metabolic or endocrine diseases.
- Genetic diseases (idiopathic).
Ventricular expansion
The main reason for the expansion of the cavity of the left ventricle is its overflow with blood. If the semilunar valve is damaged, or the ascending aorta is narrowed, then the heart muscle will need more strength and time to expel fluid into the systemic bed. Part of the blood remains in the ventricle, and over time, it stretches. The second reason may be an infection or pathology of the muscle fibers, due to which the wall of the heart becomes thinner, becomes flabby and unable to contract.
The right ventricle may increase in size due toproblems with the pulmonary valve and increased pressure in the pulmonary circulation. When the vessels of the lungs are too narrow, some of the blood from the pulmonary trunk returns to the ventricle. At this moment, a new portion of fluid comes from the atrium and the walls of the chamber are stretched. In addition, some people have birth defects of the pulmonary artery. This leads to a constant increase in pressure in the right ventricle and an increase in its volume.
Atrial expansion
The reason for the expansion of the left atrium is the pathology of the valves: atrioventricular or semilunar. In order to push the blood into the ventricle through a small hole, a lot of force and time is needed, so some of the blood remains in the atrium. Gradually, the amount of residual fluid increases, and a new portion of blood stretches the walls of the chamber of the heart. The second reason for the expansion of the walls of the left atrium is atrial fibrillation. In this case, the pathogenesis is not fully understood.
The right atrium expands in the presence of pulmonary hypertension. When the vessels of the lungs narrow, there is a high probability of backflow of blood into the right ventricle. And since it is already filled with a new portion of liquid, the pressure on the chamber walls increases. The atrioventricular valve does not withstand and turns out. So the blood goes back to the atrium. In second place are congenital heart defects. In this case, the anatomical structure of the organ is disturbed, so communication between the two atria and mixing of blood is possible. This leads to overstretching of the walls andpersistent expansion.
Aortic dilation
Aortic aneurysm may be due to expansion of the cavity of the left ventricle. It occurs in the place where the vessel wall is most thinned. Increased pressure, as well as the rigidity of the surrounding tissues due to atherosclerosis, increase the load on the insolvent areas of the vascular wall. A saccular protrusion is formed, which creates additional swirls of blood flows. An aneurysm is dangerous due to sudden rupture and internal bleeding, as well as a source of blood clots.
Dilatation treatment
Traditionally, therapy is divided into medical and surgical. Since pills cannot reduce the stretched chambers of the heart, the treatment is aimed at the etiological factor: inflammation, high blood pressure, rheumatism, atherosclerosis, or lung disease. Patients should lead a he althy lifestyle and follow the doctor's recommendations. In addition, the patient is given medication to thin the blood to facilitate its passage through the altered chambers of the heart.
Surgical methods include the implantation of a pacemaker, which will effectively reduce the stretched wall of the heart.
Prevention
In order to prevent the development of myocardial pathology, elementary rules must be followed:
- give up bad habits (tobacco, alcohol);
- observe the regime of work and rest;
- eat right;
Returning to our questions: How many chambers are there in the human heart? How does blood move through the body? What feeds the heart? Andhow does it all work? We hope that after reading the complex anatomy and physiology of the body has become a little clearer.
