The heart is the most important organ in the human body. Scientists of all fields of knowledge are engaged in its study. People are trying to find a way to extend the health of the heart muscle, improve its performance. Knowing the anatomy, physiology and pathology of the heart, even an average person will help to better understand the processes that occur in our body. How many cameras in a person’s heart? Where do blood circulation circles begin and end? How is the blood supply to the heart? All these questions can be answered in this article.
Heart anatomy
The heart is a three-layer sac. Outside it is covered by the pericardium (protective bag), behind it are the myocardium (contracting muscle) and the endocardium (thin mucous plate covering the inside of the heart chamber).
In the human body, the organ is located in the center of the chest. It is slightly deviated from 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 that are under them. Between themselves, they are separated by valves that impede the reverse flow 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 take fluid.
Features of the structure of the heart in the fetus and newborn
How many cameras are there 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 still no small circle of blood circulation - the lungs are not straightened. But blood still enters the developing respiratory organs, and it goes directly from the aorta through the botall duct.
The chambers of the heart of the fetus are thinner and significantly smaller than in adults, and only thirty percent of the total mass of the myocardium is reduced. Its functions are closely related to the flow of glucose into the maternal bloodstream, since the heart muscle of the child uses it as a nutrient substrate.
Blood supply and circulatory system
Myocardial blood supply occurs from the moment of systole, when blood under pressure enters the main vessels. The vessels of the heart chambers are located in the thickness of the myocardium. Large coronary arteries depart directly from the aorta and when the ventricles contract, part of the blood goes to nourish the heart. If this mechanism is violated at any stage, myocardial infarction occurs.
Human heart chambers perform a pumping function. From the point of view of physics, they simply pump fluid in a vicious circle. The pressure that is created in the cavity of the left ventricle, during its contraction, blood will accelerate so that it reaches even the smallest capillaries.
Two blood circulation circles are known:
- large, designed to nourish body tissues;
- small, functioning exclusively in the lungs and supporting gas exchange.
Each chamber of the heart has bringing and taking vessels. Where does the great blood circulation come from? From the left atrium, the fluid enters the left ventricle and fills it, thereby increasing the pressure in the cavity. When it reaches 120 mm water column, the lunar valve separating the ventricle from the aorta opens, and the blood enters the systemic circulation. After all the capillaries are filled, the process of cellular respiration and nutrition. Then, through the venous system, blood flows back into the heart, or rather, into the right atrium. The upper and lower vena cava, collecting blood from the whole body, are suitable for it. When a sufficient amount of fluid accumulates, it rushes into the right ventricle.
From it begins a small circle of blood circulation. Saturated with carbon dioxide and metabolic products, blood enters the pulmonary trunk. And from there to the arteries and capillaries of the lungs. Through the blood-alveolar barrier, gas exchange occurs with the external environment. Already rich in oxygen, the blood returns to the left atrium to get back into the great circle of blood circulation. The whole cycle takes less than thirty seconds.
Work cycle
In order for the body to constantly receive the necessary nutrients and oxygen, the heart chambers must work very harmoniously. There is a nature-determined course of action.
1. Systole is a contraction of the ventricles. It is divided into several periods:
- Tension: individual myofibrils are reduced, 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.
- Exile: lunar 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 a relaxation of the myocardium and a period of passive blood intake. The upper chambers of the heart communicate with the bringing vessels and accumulate a certain amount of blood. Then the atrioventricular valves open and fluid flows into the ventricles.
Diagnosis of disorders in the structure and work of the heart
- Electrocardiography This is the registration of electronic phenomena that accompany muscle contractions. The heart chambers are composed of cardiomyocytes, which generate an action potential before each contraction. It is him and fix the electrons superimposed on the chest. Thanks to this method of visualization, it is possible to identify gross violations in the work of the heart, its organic or functional damage (heart attack, defect, expansion of the cavities, the presence of additional contractions).
- Auscultation. Listening to a beating of the heart was the most ancient way to detect his illness. Experienced doctors using only this method alone can identify most structural and functional pathologies.
- Ultrasound procedure. It allows you to see the structure of the heart chambers, blood distribution, the presence of defects in the muscle and many other nuances that help to make a diagnosis. The method is based on the fact that ultrasonic waves are reflected from solids (bones, muscles, organ parenchyma) and pass freely through the fluid.
Pathology of the heart
As in any other organ, pathological changes that provoke the development of diseases accumulate in the heart with age. Even with a healthy lifestyle and constant monitoring of health, no one is immune from problems with the cardiovascular system. Pathological processes can be associated with a violation of the function or structure of the organ, capture one, two or three of its shell.
The following nosological forms of pathologies are distinguished:
- disturbances in the rhythm and electrical conduction of the heart (extrasystole, blockade, fibrillation);
- inflammatory diseases: endo-, myo-, peri-, pankarditis;
- acquired or congenital malformations;
- hypertension and ischemic lesions;
- vascular lesions;
- pathological changes in the myocardial wall.
The last type of pathology needs to be analyzed in more detail, since it is directly related to the chambers of the heart.
Dilation of the 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 thickening).
The causes of dilated cardiomyopathy are:
- Infections of various etiologies (fungi, virus, bacteria, parasites).
- Toxins (alcohol, drugs, heavy metals).
- Systemic diseases of the connective tissue (rheumatism, systemic lupus erythematosus).
- Adrenal gland tumor.
- Hereditary muscular dystrophy.
- The presence of metabolic or endocrine diseases.
- Genetic diseases (idiopathic).
Ventricular dilatation
The main reason for the expansion of the cavity of the left ventricle is its overflow with blood. If the lunar valve is damaged, or the ascending part of the aorta is narrowed, then the heart muscle will need more strength and time to expel the 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 muscle fibers, due to which the heart wall becomes thinner, becomes flabby and unable to contract.
The right ventricle can increase in size due to problems with the pulmonary valve and increased pressure in the pulmonary circulation. When the vessels of the lungs are too narrow, part of the blood from the pulmonary trunk returns to the ventricle. At this moment, a new portion of the fluid comes from the atrium and the walls of the chamber are stretched. In addition, some people have birth defects in 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 lunate. In order to push blood into the ventricle through a small hole, a lot of force and time are needed, so part 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 heart chamber. 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 are narrowed, there is a high probability of a reverse flow of blood into the right ventricle. And since it is already filled with a new portion of liquid, the pressure on the walls of the chamber increases. The atrioventricular valve does not stand 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, therefore, communication between the two atria and mixing of blood is possible. This leads to overstretching of the walls and their persistent expansion.
Aortic enlargement
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 rigidity of the surrounding tissues due to atherosclerosis, increase the load on the insolvent sections of the vascular wall. A saccular protrusion forms, which creates additional turbulence in the blood flow. Aneurysm is dangerous due to sudden rupture and internal bleeding, as well as a source of blood clots.
Dilation treatment
Traditionally, therapy is divided into medical and surgical. Since tablets cannot reduce the stretched chambers of the heart, the treatment is aimed at the etiological factor: inflammation, high blood pressure, rheumatism, atherosclerosis or lung diseases. Patients should lead a healthy lifestyle and follow the doctor's recommendations. In addition, blood is diluted with medication to the patient, which facilitates its passage through the altered chambers of the heart.
Surgical methods include implantation of a stimulator, which will contribute to the effective reduction of the stretched heart wall.
Prevention
In order to prevent the development of myocardial pathology, you need to follow the basic rules:
- give up bad habits (tobacco, alcohol);
- observe the mode of work and rest;
- Healthy food;
Returning to our questions: How many cameras are in the human heart? How does blood move through the body? What nourishes the heart? And how does it all work? We hope that after reading the complex anatomy and physiology of the body has become a little clearer.