Blood is pumped out of the left side of your heart into the arteries – the blood vessels that carry the blood’s oxygen and nutrients to your body.

As the blood pumps out of the heart and into the arteries, it pushes against the artery walls.

Blood pressure is the measurement of the pressure of the blood in the artery.

Blood pressure peaks when the heart muscle contracts and pumps blood, a cycle called systole.

It falls when the heart relaxes and refills with blood, a cycle called diastole.

Systole is the top number and diastole is the bottom number. It is displayed as two numbers, e.g 120/80 mmHg.