Blood Pressure Information
As blood is pumped from your heart into your vessels, pressure sends it to all other parts of your body. As the vessels travel away from the heart, they branch off and gradually get smaller -- one branch may go to the brain, while another may go to your kidneys. Blood pressure keeps the blood flowing through all these branches so your body's cells get the oxygen and nutrients they need.
Blood pressure is measured using a fabric cuff wrapped around the arm, which is then slightly inflated. The two numbers read from the gauge measure the pressure inside the vessels both when the heart is beating and when it is at rest. They are written like a fraction: one number on top (systolic pressure) and one on the bottom (diastolic pressure).
(Click Blood Pressure for more information, including exactly how the measurement is taken, how a person's "normal" blood pressure is determined, and factors that can affect a reading.)