Lesson Two - Cardio-Pulmonary

What is it and how is it measured?

If you have ever been to see a doctor, chances are high that someone wrapped an inflatable cuff around your arm and took your blood pressure. That cuff and machine are called a sphygmomanometer (do not worry, you will not be tested on your ability to spell it), more commonly known as a blood pressure machine. The machine, or the person listening with the stethoscope, is listening for the sound of blood going through the brachial artery (the major artery of the arm). When the pressure of the cuff is high enough, it will block the flow of blood through the brachial artery. By slowly decreasing the pressure on the cuff, one can hear the blood moving through the artery and when the sound stops. The pressure at which blood is heard moving through the artery is the amount of pressure in the arteries when your heart is contracting, the systolic blood pressure. The pressure when the sound cannot be heard anymore is the amount of pressure in your arteries when the heart is at rest, the diastolic blood pressure. These numbers are written as a fraction with the systolic number written on top and the diastolic number written on the bottom. Normal blood pressure for most young adults is below 120/80, but it can vary based on age and gender.