Heartbeat is defined as the rhythmic contraction and relaxation of auricles and ventricles. The human heart beats about 72 times per minute. One heartbeat includes systole which is a phase of contraction of heart muscle and diastole which is a phase of relaxation of the heart muscle. Doctors use a stethoscope to hear the heartbeat.

Antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Two types of antibodies called Anti-A antibody and Anti-B antibody are found in human blood plasma. Persons with one antigen have natural antibodies in their plasma against other antigen.

Hypertension is a condition in which blood pressure in arteries remains persistently higher than normal 120 / 80 mm Hg. Blood pressure above 140 / 90 regularly is regarded as hypertension. In a hypertensive heart, the walls of ventricles get thickened. This causes the cardiac muscles to work harder, increasing the risk of a heart attack. Very high blood pressure may cause dizziness. Hereditary factors, obesity, lack of physical activity, caffeine, cigarette smoking, processed food, a diet with high salt, are the major causes of hypertension.