Your cardiovascular system is made up of your heart, arteries, veins and capillaries. The heart has four separate chambers--two atria, or upper chambers, and two ventricles, or lower chambers. The right atrium and ventricle accept blood from your body and pump it into your lungs. The left atrium and ventricle receive blood from your lungs and pump it into the main artery of your body, the aorta.
Stroke volume is the amount of blood the left ventricle pushes out in one beat. Aerobic exercise increases your stroke volume. When your stroke volume increases, your heart does not have to beat as many beats to deliver the same amount of blood to your body. A healthy cardiovascular system means your heart can easily expand and contract, increasing your stroke volume.
Arteries deliver oxygenated blood to your cells. Your arteries are elastic in that they easily open and contract to pump blood throughout your body, especially to those parts farthest from your heart. When plaque builds up within your artery walls, it decreases their elasticity and the size of the opening. Less blood can flow through diseased arteries.
Cardiovascular exercise reduces the amount of plaque buildup and maintains the elasticity of your arteries. Aerobic exercise also increases the number of capillaries in your working muscles. A healthy cardiovascular system can deliver more blood at a faster rate to exercising muscles.
A healthy cardiovascular system through aerobic exercise stimulates the production of more enzymes, which convert the food you eat into energy your cells can use. It also stimulates the formation of more mitochondria, the cell structure where energy production takes place. The more aerobic exercise you do, the greater the improvement in your cardiovascular system. A more improved cardiovascular system enhances your aerobic fitness, making you a faster runner, swimmer or cyclist.
The ease at which your cardiovascular system can pump and transport blood and enhance energy production decreases your risk of chronic disease. Such diseases include heart disease, high blood pressure and high cholesterol. Aerobic exercise stimulates the production of the good cholesterol in your blood. These good cholesterol carriers remove plaque/cholesterol, maintaining the function of your blood vessels, decreasing your risk of a heart attack and stroke and preserving normal blood pressure.
A healthy cardiovascular system improves your body's ability to regulate body temperature. In a hot environment, the blood vessels leading toward your skin dilate to cool your blood and therefore your body. In cold temperatures, your cardiovascular system must work to constrict the blood vessels in your limbs, directing blood to your internal organs, maintaining core body temperature.