What is Heart? How does it work ?


Our heart, which contains many miraculous mechanisms from its micro structure to its macro structure, is a “pump” or “suction-discharge pump” system, in the simplest terms. This pump system ensures that the “blood”, which is necessary for the transportation of all substances required for the continuation of life, to the farthest corners of the body, circulates in a continuous manner without interruption. However, in simple suction-discharge pump systems, there is intermittent rather than continuous flow of water, while blood flows uninterruptedly forward in the body. That is, even when the heart relaxes and draws in blood, the blood continues to flow forward without hesitation.

The work of the heart is summarized in the diagram below. If we talk about it in one sentence: The heart takes the clean blood it sends to the body back after it is used, sends it to the lungs to be cleaned, and then takes it back again after cleaning and sends it to the body.

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The heart is our most vital organ, located at the center of the circulatory system. It is located just behind the anterior chest wall, slightly to the left, in the middle of both lungs, in the anterior part of the esophagus.

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In order to understand heart diseases, first of all, it is necessary to understand the structure of the heart and what it consists of. Since the details will be entered in the topic of diseases, let’s list the building blocks of the heart as the main headings.


Since the heart’s final job is to “pump blood”, muscles will of course form the basis of the system. Cardiac muscle belongs to the class of “involuntary (involuntary) working” smooth muscle.

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2. ELECTRIC (Rhythm and Transmission) SYSTEM

Yes, we said that the heart muscles have a special structure that works out of our will. So what is the mechanism that activates these muscles? Here it would be correct to establish the following sentence: “The heart produces and uses its own electricity. The muscles are prompted to contract with this electricity.

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While the muscles contract with the propulsion of the electrical system, the veins bring the blood that will provide the necessary energy. This system, called “Coronary Vessels”, has an important place in heart diseases. Because heart attacks, which are in the first place among the causes of death, occur when this vascular system is blocked.

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When the blood is filled into the heart, the valves that provide the transitions between the cavities direct the blood movement by opening and closing synchronously, preventing the blood from flowing in the opposite direction with the pressures inside the heart.

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The membrane system surrounding the heart, which is in constant motion in the chest cavity, both protects the heart and prevents friction with the small amount of fluid it contains.



When the heart pumps, blood first opens the aortic valve with the built-up pressure and moves into the aorta, the main artery of the body. 3 veins are separated from the area where the aorta curves, and blood is delivered to the arms, upper chest area, neck and all structures in the head. After the aortic arch, the part called the Descending Aorta begins and the blood movement from here reaches all the rest of the body parts.

Used by the body, which has left its oxygen to the tissues, so “oxygen-poor blood” (although an incorrect expression, “dirty blood”) enters the Right Atrium (Right Atrium) of the heart from the Lower and Upper Vena Cava via the vein networks. From here, it is first transmitted to the Right Ventricle (Right Ventricle) by passing through the Tricuspid valve, and then to the Main Pulmonary Vein by passing through the Pulmonary valve with the pumping of the heart. The Main Pulmonary Artery is divided into two branches as right and left, and blood is delivered to the Lung regions on both sides.

In the extensive vascular network of the lung, the blood meets the oxygen taken from the air and becomes “oxygen-rich” (clean!) again. Oxygenated blood reaches the Left Atrium (Left Atrium) through two Pulmonary Veins coming from the right and left Lungs, and from there to the Left Ventricle by passing through the Mitral Valve. As we mentioned, the left ventricle is the main heart chamber that pumps blood throughout the body.

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To summarize again;

In the Sinoatrial (SA) node, which is under the control of the brain and hormones and located in the right atrium, which we can call the “electric generator”, the electric current generated by the displacement of electrically charged ions into and out of the cell within a rule ensures the heart to work. The electric current primarily spreads to the atria, causing the atria to contract and evacuating the blood into the ventricles through the Tricuspid on the right side and the Mitral valve on the left.

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Meanwhile, the electrical current transmitted from the SA node to the AV node (a kind of electrical transfer transformer) is kept here for a very short time. Because the contraction of the atria and the discharge of the blood into the ventricles is not finished yet. If the electric current was not kept here, the ventricles would start to contract and the blood flow order would be disrupted before the atria are fully emptied.

Yes, after a short delay in the AV node, the electricity transmitted downstream quickly spreads to both ventricles through the right and left branches of the conduction system, causing the ventricles to contract. The ventricles contract and open the aortic and pulmonary valves with pressure and send the blood inside them. The right side is via the Pulmonary artery, to the lungs, and the left side is to the whole body via the Aorta… After the pumping process completed in a short time, the electrical movement on the conduction system returns to the resting position with the intra-extracellular movements of the ions and the ventricle muscles of the heart begin to relax. . As the ventricles return to their resting position, the SA node is about to re-contract the atria by producing a new electrical current at that moment. As the ventricles relax, they absorb the blood inside the auricles with the help of the contraction of the atria… The ventricles are filled and the cycle continues in this way, as it started in the 7th week in the mother’s womb, for a lifetime. The energy required for all these processes is delivered to the heart by the coronary vessels.

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