Explain in detail about working of heart

Heart has four chambers. Two upper chambers are called atria. Two muscular lower chambers are called ventricles.

The right and left atrium are separated from each other by interatrial septum. Likewise the right and left ventricles are completely separated from each other by interventricular septum.

There are atrio ventricular (AV) valves between atria and ventricles:

The right atrio ventricular valve is also known as tricuspid valve because it has three flaps. This valve allows blood to flow from right atrium to right ventricle but prevent blood flow in opposite direction.

Left AV valve is also known as bicuspid valve because of having two flaps. This valve is also called mitral valve and it allows blood to flow from left atrium to left ventricle but not in opposite direction.

Heart is a pumping organ. It receives blood from all parts of the body in atria and pumps out blood to all parts of the body by ventricles. Blood leaves the left ventricle by the large artery called as aorta. This function is performed by the rhythmic contraction and relaxation of heart muscles. Whole of the heart does not contract or relax at the same time. When atria contract, ventricles relax and when ventricles contract, atria relax. The period of contraction is called systole and period of relaxation is called diastole.

A heart beat includes systole and diastoles of the atria and ventricles. Heart beats can be heard over chest by stethoscope. This heart beat transmits through arteries and can be felt at wrist. This is called pulse beat. Under normal condition, rate of heart beats and pulse beats are same.

The function of the heart is to maintain a regular blood supply to the body by rhythmic contractions of its muscles. The rate of contraction in healthy individual at rest is 72 beats per minute. The rate of heart beat is controlled by nervous system.