Importance of blood pressure for diastole
What do the phases of the heart action have to do with blood pressure? There is a certain pressure in the vessels, the diastolic blood pressure, which is caused by the blood in the vessels when the heart is in its “resting phase”, i.e. when it is being filled. This pressure depends on the amount of blood the heart pumps at any given time and the diameter of the blood vessels.
The diastolic blood pressure should be around 80mmHg (i.e. millimeters of mercury). In the expulsion phase, however, the heart must generate a higher pressure than the diastolic pressure in order for the blood to be pumped into the vessels. This is because the blood always flows from the higher to the lower pressure.
During systole, the heart generates a pressure of about 120 mmHg, which is pumped into the vessels and from there through the body’s circulation. During the filling phase of the heart, the blood pressure drops back to the diastolic “low point”. Thus, blood pressure is composed of two values, a systolic and a diastolic: 120/80 mmHg (standard value).
These two values can be abnormally high or low. A low diastolic blood pressure is defined as one that is below 60 mmHg.
