How blood pressure comes about
The circulation of blood through the body has the important task of supplying all the organs and tissues with blood. This blood circulation provides the cells with oxygen and nutrients, and carries carbon dioxide and waste products away.
The heart is the most important part of the circulatory system. Its pumping action propels the blood around the body. For this purpose, the heart beats regularly approx. 60 to 80 times per minute. During each heartbeat the heart muscle contracts (systole) and presses blood into the circulatory system. As a result, the blood pressure in the arteries increases, which causes the arteries coming directly from the heart to propel blood into the organs and tissues.
During the relaxation or rest phase of the heart muscle (diastole) the heart expands and fills with blood. This reduces the blood pressure. The blood taken in in this way is expelled again during the next heartbeat and flows through the arteries to the organs and tissues.
There are therefore two values that must be distinguished when measuring blood pressure: the systolic and the diastolic blood pressure. The systolic blood pressure is the higher figure, which indicates the pressure when the heart contracts during pumping. The diastolic blood pressure is the lower figure, which indicates the pressure when the heart relaxes during the rest phase.