The heart is the organ that acts as a pump and allows blood to circulate throughout the body. Although they differ in structure, most invertebrates and all vertebrates have a heart. Although the way this heart works and distributes blood differs slightly, it is almost the same in every living thing.
In humans, the heart is located in the thoracic cavity between the two lungs, adjacent to the left lung. The heart of adult humans is an organ in the size of a fist and weighs 250-300 grams. The heart has a unique muscle structure. This special muscle is called the cardiac muscle. The heart muscle is the only striated muscle structure in our body that does not work of our own will. The contraction and relaxation of this muscle allows blood to spread throughout the body. The activation of the muscle is also provided by a small electric current circulating on it.
The inside of the heart has a hollow structure so that blood can easily enter and exit. This section consists of four chambers. Above these chambers, two identical sections are atrium; The two identical parts at the bottom are called ventricles. While the wall structures of the atria are thin, the wall structures of the ventricles are thick. Atria and ventricles according to their side; They are called right atrium, left atrium, right ventricle, left ventricle.
The right and left parts of the heart do not conduct blood directly to each other. That is, there is no gateway to each other. Heart valves only conduct blood from the atria to the ventricle. Since the heart valves open towards the ventricle, the blood given from the atria cannot escape back.
Contaminated and carbon dioxide-rich blood enters the right side of the heart. This blood is sent to the lungs for purification. Clean blood comes to the left part, cleaned by the lungs. This blood is also distributed throughout the body. While there are main arteries at the exits of the right and left ventricles; The main veins are located at the entrances of the right and left atria.
