The heart in the human body is a vital organ. Its work can be compared to a pump. Thanks to the heart, blood is pumped into the arteries and constantly moves through the vessels. This organ functions throughout a person's life. For 70 years, it performs approximately 2-3 billion contractions and pumps more than 170 million liters of blood. So how is the heart? What are its functions?
Location and size of the heart
The main organ of the human body is located in the center of the chest. Most of the heart is located on the left side of the body, and the smaller part is on the right. The organ lies in the pericardial sac. It is also called the pericardium. This is a tight bag that separates the heart from other internal organs and does not allow it to move and overstretch during physical exertion.
The size of the heart is quite small. Each person has it about the size of a fist. However, the size and weight of the organ can vary. Parameters increase with some ailments. The size and weight of the heart also increase in those individuals who have been involved in sports or strenuous physical labor for a long period of time.
Organ structure
Let's see how the heart works. The walls of this organ form three layers:
- Epicardium. This is the thin membraneous outer layer of the heart wall.
- Myocardium. By this term, experts understand the middle layer responsible for the muscle contractions of the heart.
- Endocardium. It is a membrane that limits the internal system of the heart.
This vital organ consists of two parts separated by a septum - a thick muscular wall. Each half includes two chambers. The upper sections (right and left) are called the atria, and the lower sections are called the ventricles. Each chamber plays a specific role in the circulation process.
Atrials
Considering how the heart works, it is worth talking about the atria - the thin-walled chambers of the heart. They are located above the ventricles and are separated from them by atrioventricular valves. Separate the right and left atria. The right upper chamber of the organ is the confluence of the vena cava and the veins of the heart itself. Based on this information, we can conclude that this atrium receives oxygen-deprived venous blood.
The left upper chamber of the organ is smaller in size than the right one. Four openings of the pulmonary veins open into it. From them, fresh blood enters the left atrium, saturated with oxygen and ready for further distribution throughout the human body.
Ventricles
In the picture, which shows how the human heart works (photo below), you cansee the right and left ventricles. They form the main muscle mass of the body. It should be noted that the left camera is more massive and powerful than the right one. The right ventricle receives venous blood from the right atrium. When the heart muscle contracts, it is sent to the lungs through the pulmonic valve. The backflow of blood into the upper chamber is prevented by the tricuspid valve, also called the tricuspid valve.
The left ventricle receives oxygenated blood from the left atrium. It enters through the mitral (bicuspid) valve. When the muscles of the left lower chamber contract, blood is pushed into the aorta through the aortic valve. Then it spreads throughout the human body.
Heart work
When considering how the heart works, it is necessary to study the work of the organ. The ventricles and atria can be either relaxed (diastolic) or contracted (systolic). Relaxations and contractions of the heart occur in a certain sequence:
- Atrial systole. The contraction of the upper chambers of the organ is the beginning of the cardiac cycle. This phase lasts 0.1 s. During systole, the cusp valves open. All blood from the atria is sent to the ventricles. After contraction of the upper chambers, the relaxation phase begins.
- Ventricular systole. The contraction of the lower parts of the heart lasts 0.3 s. The semilunar (pulmonary and aortic) and leaflet valves are closed at the beginning of the phase. The muscles of the ventricles are reduced. Because of this, the pressure in the cavitiesrises. As a result, blood is directed to the atria. The pressure is lower there. However, cuspid valves prevent blood flow in this direction. Their valves cannot turn inside the atria. At this point, the semilunar valves open. Blood begins to move through the pulmonary artery and aorta.
- Diastole. The ventricles relax after contraction. This phase lasts 0.4 s. During the rest period of the organ, blood enters from the veins into the atria and partially penetrates into the ventricles. When a new cycle begins, the remnants of blood from the upper chambers of the organ are pushed into its lower sections.
Considering how the heart is arranged and how it works, it is worth talking about the circles of blood circulation - large and small. The first of these begins with the aorta. It receives oxygenated blood from the left ventricle. From the largest arterial vessel, it flows through the arteries, arterioles, capillaries, delivering oxygen to all cells and freeing them from accumulated carbon dioxide. As a result, venous blood leaves the capillary network. First, it moves through the venules, and then through the veins and vena cava. As a result, it enters the right atrium, and from there it goes to the right ventricle.
The pulmonary circulation begins with the pulmonary artery emerging from the right lower chamber of the heart. Venous blood enters the lungs, moves through the arteries, arterioles and the thinnest capillaries located in these organs. As a result, it gets to the alveoli - tiny bubbles that are filled with air. The blood absorbsoxygen is purified from carbon dioxide and enters the veins. These blood vessels go to the left atrium. From it, blood is pushed into the left ventricle. Then everything repeats from the beginning. The blood begins to move through the systemic circulation.
Functions of Organ
Having considered how the heart works, we can name its functions. One of them is reservoir. During the period of relaxation of the heart muscle, a vital organ of the human body serves as a cavity for the accumulation of the next portion of blood coming from the blood vessels to the atria. The second function of the heart is pumping. It consists in the ejection of blood into the small and large circles of blood circulation during the contraction of the ventricles.
Everyone should know how the human heart works. Everyone needs to have information about how his body works, what processes take place in it. The well-being and he alth of a person depends on the work of the heart. Thanks to the functioning of this organ, the blood spreads throughout the body, supplies all organs and tissues with oxygen, biologically active substances, energy and takes away carbon dioxide and excretion products from them.
