The heart consists of a right and a left half and is divided into four chambers. The cardiac septum, also called the septum cordis, runs longitudinally between the two halves of the heart. The septum separates the four chambers of the heart into left and right atria, and left and right ventricles. The terms cardiac ventricle or ventriculus cordis are also used synonymously.
What is the ventricle?
The left ventricle is a component of the systemic circulation downstream from the left atrium. It is responsible for supplying the systemic circulation with blood freshly arriving from the lungs via the aorta. The right ventricle is part of the pulmonary circulation and is located downstream of the right atrium. It pumps the venous blood, which has absorbed larger quantities of carbon dioxide as a breakdown product from the cells, into the pulmonary vessels. There, the decomposition product is exhaled and the blood can take up oxygen again. The arterial blood then flows into the systemic circulation via the left ventricle.
Anatomy and structure
The fist-sized heart is nestled between the two lungs. It is located above the diaphragm. The heart wall has three layers. The endocardium forms the inner lining of the heart, and the myocardium (heart muscle) forms a large part of the heart wall. The epicardium covers the coronary vessels and the surface of the heart. It is very thinly formed and regularly releases a clear fluid to help the heart glide in the pericardium during pumping. The pericardium is made of connective tissue that surrounds the heart. It consists of the left and right halves and is divided into four chambers. The two halves of the heart are separated longitudinally by the septum (cardiac septum). This divides the four chambers into a right and a left ventricle and a right and a left atrium. The ventricles and atria are separated horizontally by so-called leaflet valves. The right valve is called the tricuspid valve, and the left valve is called the mitral valve. These heart valves function according to the principle of a check valve. They ensure that blood flow within the heart occurs in only one direction. The right side of the heart faces the anterior chest wall (ventral), while the left side faces the posterior (dorsal). The left ventricle is part of the systemic circulation, while the right ventricle is part of the pulmonary circulation.
Function and Tasks
The heart connects the pulmonary and systemic circulations. According to its anatomy, it constantly pumps blood throughout the body and supplies oxygen to the organs. A healthy heart beats about 70 times per minute and carries 70 milliliters of blood with each heartbeat, which corresponds to a blood volume of five liters per minute. A complicated system of excitation conductors ensures that the pumping function runs smoothly. The sinoatrial node, located in the right atrium, generates the electrical impulse needed to excite the heart muscle. From this point, the electrical impulses travel along the atria and ventricles and spread to the apex of the heart. The inferior and superior vena cava open into the right atrium. Venous (oxygen-depleted) blood from the systemic circulation flows to the heart through these vena cavae. The blood then flows from the right atrium into the right ventricle of the heart and into the lungs via the pulmonary artery (pulmonary artery). Between the heart and the pulmonary artery is the pulmonary valve, which is shaped like a pocket. Via the pulmonary veins, arterial blood saturated with oxygen flows from the lungs into the left atrium. It is then transferred to the left ventricle and returns to the organs via the aorta (main artery). At the point of origin of the aorta there is also a pocket valve, the aortic valve. From the outside, the heart is supplied by means of small blood vessels. These blood vessels are called coronary arteries or coronary vessels. They branch off from the aorta, which branches off from the left ventricle of the heart. The right and left coronary arteries form the coronary arteries. They have numerous fine branches. Their function is to regularly supply the heart muscle with oxygen. The pumping action of the heart occurs regularly in three steps. The first step is the filling phase (diastole). The heart muscle relaxes. Oxygen-depleted blood flows through the vena cavae into the right atrium and then into the right ventricle.At the same time, oxygen-saturated blood flows from the lungs into the left atrium. It is then transferred to the left ventricle. The leaflet valves close when the ventricles have a higher filling pressure than the atria. In the second step, the tense phase occurs. The two atria contract and increase the amount of blood in the ventricles. In the third step, the expulsion phase (systole) occurs. The heart muscle contracts and the blood in the chambers flows into the systemic and pulmonary circulation via the large blood vessels. The closed leaflet valves prevent the blood from flowing back into the atria. The increasing emptying decreases the pressure existing in the ventricles. The tightly closed leaflet valves prevent backflow of blood from the great vessels into the ventricles. The drop in pressure causes the ventricles to fill again with the blood present in the atria. Now the cycle repeats with diastole and systole.
Diseases
In left heart failure, the left ventricle does not work adequately because of a pumping weakness. Shortness of breath occurs, and usually breathing is accelerated (tachypnea). Patients suffer from cold sweats, coughing and a rattling in the lungs. Other symptoms include lung congestion, pulmonary edema, and feelings of restlessness. The medical term is asthma cardiale. If a patient suffers from right heart failure, water is deposited in the ankles and shins. Sufferers experience an increased urge to urinate as water is flushed out of the tissues into the blood and excreted in the urine. Skin edema occurs around the genitals, buttocks, and flanks. As blood pools in the veins in front of the right heart, the neck veins are severely filled. The venous blood is deposited in various organs, and enlargement of the liver (congested liver) and accumulation of water (ascites) in the abdomen may occur. Inflammation is possible in the gastric veins, causing gastritis (stasis gastritis). It is accompanied by a feeling of fullness and loss of appetite. Only in rare cases do these two heart diseases occur separately. Most patients suffer from global heart failure, in which both chambers of the heart are no longer working adequately.
