Your cardiovascular system is made up of the heart, blood vessels and blood. Your heart acts as a pump to move blood through blood vessels and to the organs of the body. When blood returns from the tissues it is pumped to the lungs where red blood cells unload carbon dioxide and take up oxygen.
In addition to providing oxygen and removing carbon dioxide from the body, your cardiovascular system helps to maintain pH, temperature, deliver nutrients and remove waste products. Because of its important role as a delivery system the blood contains markers that are used as measurements of health. The levels of blood markers change over time but each has a range of values that can be used to assess cardiovascular health and help to diagnose illness. These markers are important to test because changes often occur before disease develops and detecting changes early allows for modifications to the diet or treatments to reduce the risk of disease.