Blood Pressure
Lub-dub! Lub-dub! Lub-dub! This sound is made by the rapid contracting and extending of the chamber doors on the inside of the heart. This ventricular contracting injects roughly 70 mL of blood into a vascular system with a given volume at differing pressure. Blood pressure refers to the pressure in the arterial system; and it is typically taken in the brachial artery of the arm because the pressure at different places along the circulatory route is different. Blood pressure is simply the force that the blood exerts in all directions within any given area and is the basis for the movement of blood from the heart, through the body, and back to the heart. This pressure is commonly expressed as a ratio of the systolic pressure over the diastolic pressure. The systolic pressure or “high peak” pressure takes place within the arterial system as ventricles contract and force blood into the arteries. The diastolic pressure or “low peak” pressure takes place within this arterial system just before the next ventricular contraction. An increase in blood pressure can occur if the arterial walls lose some of their elasticity with age or disease.