High blood pressure is the narrowing and hardening of the arteries which increase their resistance and pressure and make the heart work harder. Untreated hypertension may lead to heart disease and strokes. High blood pressure is defined was being over 140/90mm Hg. Normal blood pressure should range from 100/70 to 120/80. The higher number presents the systolic blood pressure, the BP while the heart pumps; lower number presents the diastolic BP during the rest between beats.