Blood Pressure
Blood pressure measures the force of blood exerted against the walls of the arteries as it is pumped through the body. When the heart beats faster or harder than normal, when there is an increase in blood volume (such as in pregnancy for example), or when arteries are narrowed, this force increases and blood pressure rises. Blood pressure is reported as two numbers: systolic (when the heart contracts) over diastolic (when the heart is relaxed).