The heart is a muscle that pumps blood around the body continuously. Blood that is low in oxygen is pumped towards the lungs, where oxygen supplies are replenished. The heart pumps this oxygen-rich blood around the body to supply our muscles and cells. The pumping of blood generates pressure – blood pressure.
When we measure blood pressure, we gauge two different types of pressure:
* Systolic pressure – the blood pressure when the heart contracts, specifically the moment of maximum force of the contraction, which occurs when the left ventricle of the heart contracts.
* Diastolic pressure – the blood pressure between heartbeats, when the heart is resting and opening up, (dilating).
When our blood pressure is taken the doctor or nurse needs to measure both the systolic and diastolic pressures. The figures usually appear with a larger number first (systolic pressure), and then a smaller number (diastolic pressure). The figure will be followed by the abbreviation mmHg, which means millimeters of mercury.
If your blood pressure is 120 over 80 (120/80 mmHg), it means a systolic pressure of 120mmHg and a diastolic pressure of 80mmHg.
Our levels of blood pressure can fluctuate by as much as 30 or 40 mmHg during the day. It will be at its lowest point when we are asleep or resting. When we are physically active, very stressed or anxious our blood pressure rises. It is important that blood pressure is taken under similar circumstances each time so that when the readings are compared they refer to the same state of physical activity.