Blood pressure is the force with which the blood presses against the arterial vessel walls. The blood is pumped through the arteries by the heart and this exerts corresponding pressure on the vascular walls. Two digits are used to monitor blood pressure. The force at which your heart carries blood from the heart is called systolic pressure. The resistance to blood flow in the blood arteries is measured by diastolic pressure. The blood pressure varies from person to person A blood pressure of 120/80 mmHg is regarded as optimal blood pressure. Hypertension is considered to be 140/90mmHg or higher.