The heart is a powerful pump in muscular structure, usually slightly larger than a person's fist, that collects body blood through veins and directs it to the whole body through arteries. It contracts an average of 100,000 times a day and continuously pumps 8,000 liters of blood into circulation. The heart is located in the center of the chest, slightly to the left, with its base at the top and its apex at the bottom. It is surrounded by the sternum in front and the ribcage on the sides. There are 4 chambers in the heart (right and left atrium at the top and right and left ventricles at the bottom) and walls separating these chambers from each other. There is a double (mitral) valve between the left atrium and left ventricle, a triple (tricuspid) valve between the right atrium and right ventricle, the valve of the aorta coming out of the left ventricle, and the valve of the lung artery (pulmonary artery) coming out of the right ventricle. These valves ensure the unidirectional flow of blood.
Work of the heart
The electrical conduction system in the heart from top to bottom. has. In this conduction system, the point that initiates the stimulus is the sinoatrial (SA) node, which is right next to where the superior main vein opens to the upper part of the right atrium. This node (also called the sinus node), which is the natural pacemaker of the heart, emits stimuli at equal intervals and at varying speeds depending on the age and condition of the patient. This stimulus spreads downward through both atria of the heart, again through specialized conduction pathways for this purpose. Thus, the atria contract and discharge the blood inside them into the ventricles (diastole = relaxation of the heart). Afterwards, the stimulus is sent to another special area located between the atria and ventricles; reaches the atrioventricular (AV) node. It prevents the atria and ventricles from contracting simultaneously by making a 0.1-second delay in the atrioventricular node before the electrical message is delivered to the ventricles, thus ensuring that the atria contract before the ventricles. The flow passing through the atrioventricular node spreads to the ventricles via the His bundle and Purkinje fibers. When the ventricles contract, they pump the blood inside them to the lungs via the pulmonary artery and to the body via the aorta (systole = contraction of the heart). Thus, a cycle consisting of diastole and systole The lp cycle (one heartbeat) is completed. The sinus node then issues a new stimulus and starts a new cycle, and this event is repeated approximately 100,000 times a day.
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