Blood Pressure.The heart produces a characteristic "lub-dub" sound, which results from the rapid contraction and relaxation of its chambers. Each contraction, known as ventricular contraction, ejects approximately 70 mL of blood into the vascular system, which varies in volume and pressure. Blood pressure specifically refers to the pressure within the arterial system, commonly measured at the brachial artery in the arm, as pressure levels can differ at various points along the circulatory pathway. Essentially, blood pressure is the force exerted by blood in all directions within a specific area, driving the flow of blood from the heart, throughout the body, and back again. It is typically expressed as a ratio of systolic pressure over diastolic pressure. Systolic pressure, or the "high peak" pressure, occurs when the ventricles contract and push blood into the arteries, while diastolic pressure, or the "low peak" pressure, is the pressure in the arteries just before the next contraction. An increase in blood pressure may arise if arterial walls lose some elasticity due to aging or disease.