Our Heart

The human heart is located between the two lungs in the so-called mediastinum, also known as the mid-chest. Two-thirds of our heart are located in the left half of the chest and one-third in the right half. A healthy heart is about one and a half times the size of the closed fist of the respective person and weighs between 250 and 350 grams. In shape, our heart resembles a rounded cone, with the tip of this cone pointing downwards. Since the heart tip is so close to the chest wall, every heartbeat can be felt on the chest.

The heart functions as a muscular pump, ensuring that blood continuously circulates through our body. The blood supplies all body cells with oxygen and nutrients on its journey through the blood vessels. Additionally, the blood transports metabolic waste products such as carbon dioxide away.

The heart is divided into two halves by the septum, with each half having very different tasks. The right half of the heart draws in oxygen-poor blood from the veins and pumps it into the pulmonary circulation, where it is enriched with oxygen. The blood then travels through the lungs to the left half of the heart, is further pumped into the aorta - the main artery - and thus returns to the systemic circulation. Each half of the heart is further divided into two chambers: a smaller atrium, where the blood collects, and a larger and stronger ventricle, which draws blood from the atrium and pumps it back into the body - or the pulmonary circulation.

To enable the pumping function and ensure the direction of blood flow, there are a total of four heart valves in the heart. Blood flows from the right atrium through the tricuspid valve, which consists of three leaflets, into the right ventricle. From there, it continues through the pulmonary valve, a so-called pocket valve, into the pulmonary artery and thus into the pulmonary circulation. From there, it returns to the heart via the left atrium. Through the mitral valve, which consists of two leaflets, it then enters the left ventricle and is pumped through the aortic valve, the second pocket valve in our heart, into the aorta and thus into the systemic circulation. The coronary arteries, which wind around the heart and supply it, also originate directly at the exit of the aorta at the aortic valve. In the case of a heart attack, there is a blockage at a point in the coronary arteries.

The two halves of the heart work in sync. The heart and blood vessels together form the cardiovascular system, also referred to as the circulatory system.

The heart is a unique organ. It is the only muscle capable of stimulating itself independently, synchronously, regularly, and in response to load. For this purpose, there is the so-called conduction system in the heart. The aforementioned sinoatrial node is located in the right atrium. It is the body's natural pacemaker. Here, electrical impulses are generated and transmitted to other stations in the heart. Specialized heart muscle cells receive these impulses and transmit them through both atria. The next station is the AV node (atrioventricular node), which is located between the right atrium and right ventricle. It slightly delays the impulse so that the atria can contract and direct the blood into the ventricles. From the AV node, the impulse is passed on to the His bundle, from which the two bundle branches transmit the impulse to the Purkinje fibers. This ensures that all regions of the heart are reached.

A significant feature of the conduction system is that each subordinate station can generate an impulse if the predecessor fails. If the sinoatrial node does not send signals, the AV node can generate impulses itself - albeit at a slower rhythm. If the AV node also stops sending impulses, the His bundle, bundle branches, and Purkinje fibers can still stimulate the heart enough to beat at a very slow frequency.

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