Blood pressure monitor
Roll up your sleeve and measure your blood pressure. Does your blood pressure change if you exercise?
A blood pressure check is a common medical examination. Both children and adults can measure their blood pressure. Blood pressure is given using two numbers, for example 120/80 (120 over 80).
- The first number indicates the peak pressure when the heart contracts (squeezes together) and pumps blood. This is called the systolic blood pressure and measures pressure in the arteries when your heart beats.
- The second number indicates the lowest pressure, when the heart relaxes and fills with new blood. This is known as the diastolic blood pressure and tells you the pressure in the arteries between heartbeats.
Blood pressure is determined by how flexible the arteries are and the power and amount of blood being pumped around by the heart. Blood pressure is measured using millimetres of mercury (mm Hg) and it changes depending on activity levels, temperature, diet, emotional state, posture, physical condition and if you are taking any medicine.
You can measure blood pressure using a blood pressure monitor, like in the experiment. Or you can use a special blood pressure cuff and stethoscope. This method is common at medical centres. The cuff is placed on your upper arm, at the same level as your heart. A stethoscope is then placed on a blood vessel at the crease of the elbow and air is pumped into the cuff. When the pressure increases in the blood pressure cuff, the blood vessel squeezes together. When the pressure is high enough, blood cannot pass through the blood vessel in the arm.
The person measuring will slowly release the pressure from the cuff whilst listening in the stethoscope. As soon as the pulse can be heard, the peak pressure is measured – the systolic pressure. As the pressure in the cuff decreases, the sound of the pulse changes and then disappears. This is when the lowest pressure can be measured – the diastolic blood pressure.
