The first heart sound is generally longer and lower than the second, producing a heartbeat that sounds like lub-dup, lub-dup, lub-dup.

Blood pressure, the pressure exerted on the walls of blood vessels by the flowing blood, also varies during different phases of the cardiac cycle. Blood pressure in the arteries is higher during systole, when the ventricles are contracting, and lower during diastole, as the blood ejected during systole moves into the body's capillaries. Blood pressure is measured in millimeters (mm) of mercury using a sphygmomanometer, an instrument that consists of a pressure recording device and an inflatable cuff that is usually placed around the upper arm. Normal blood pressure in an adult is about 120 mm of mercury during systole, and about 80 mm of mercury during diastole. Blood pressure is usually noted as a ratio of systolic pressure to diastolic pressure for example, 120/80. A person's blood pressure...
[ View Full Essay]