Blood Pressure: What Is Normal, High, Low? Causes And Symptoms

Definition: what is blood pressure?

Blood pressure, or arterial pressure is pressure exerted by the blood on the artery walls when it is pumped around the body by the heart. It is a necessary force for the heart to be able to circulate blood around the body.

There are two types of pressure, systolic pressure is the blood pressure value during cardiac systole, which is when the heart contracts. It is at this moment that the pressure is at its highest. Diastolic pressure is the blood pressure value during cardiac diastole, meaning when the heart is relaxed.

Blood pressure is considered normal when the systolic pressure is around 120 mmHg (millimetre of mercury) and the diastolic pressure of 80mmHg. It’s the ideal blood pressure for a life expectancy without a heart disease. The most commonly indicated centimetre of mercury is an average value of 12/8.

It is considered high blood pressure when it is too high, over 140/90mmHg or 14/9cmHg. Contrarily it is low blood pressure when the pressure is abnormally low, when the systolic pressure is found around or below 90mmHg.

How to measure blood pressure

Blood pressure is measured most commonly using a tensiometer or pressure cuff which is most often an inflatable cuff which is used on the arm. The measuring must be done in a sitting or lying position to test for high blood pressure and in a standing position for low blood pressure.

Another method is also possible which is known as ambulatory blood pressure monitoring (ABP). This involves using an appliance which is worn for 24 hours, and which automatically records the blood pressure every 15 minutes during the day and 30 minutes during the night.