Picture of Blood Pressure

Blood pressure refers to the pressure the blood exerts within the arteries. Contraction of the heart muscle is the primary determinant of blood pressure. Blood pressure is indicated by two numbers. The first or “top” number in blood pressure readings is the systolic pressure. It refers to the pressure in the arteries when the heart contracts. The second or “bottom” number in blood pressure readings is the diastolic pressure. It refers to the pressure in the arteries when the heart is at rest between beats. Blood pressure is measured with a sphygmomanometer, or blood pressure cuff. Blood pressure that is too high is called hypertension. Blood pressure that is too low is called hypotension.