According to the Mayo Clinic, your cardiovascular system consists of your heart and blood vessels. Your cardiovascular system performs several important functions to keep you alive and well. Like some of your other body systems, your cardiovascular system can be strengthened and protected by participating in regular exercise. Your cardiovascular system is in a constant dynamic state, from your first heartbeat until the end of your life.
Pumping Blood
According to the National Heart Lung and Blood Institute, a division of the National Institutes of Health, your heart is a muscular organ, composed of cardiac muscle cells, that serves as a pump to continuously send blood out to your blood vessels. The Mayo Clinic suggests that, on average, your heart beats about 100,000 times per day or 36.5 million times per year. Over a typical 70-year lifespan, your heart will beat approximately 2.5 billion times. Your heart, which is slightly larger than your fist, possesses four chambers through which blood is pumped, according to the American Heart Association. These chambers, known as atria and ventricles, contract in a rhythmic fashion due to the firing of electrical impulses that originate within your heart's sinoatrial node.
Delivering Blood to Your Tissues
Your cardiovascular system is tasked with the delivery of blood to your body's tissues through your blood vessels, including your arteries, arterioles and capillaries--your tiniest blood vessels, and the location of oxygen delivery. Your cardiovascular system works in concert with your respiratory system to generate oxygen- and nutrient-rich blood, which is carried around your body to support the metabolic functions of your organs and tissues. Your cardiovascular system is also tasked with returning oxygen-depleted blood back to your heart through your venules and veins, and clearing your tissues of waste products, which are then sent to your organs of elimination, including your kidneys, liver and lungs. According to the American Heart Association, if your blood vessels were laid end-to-end, they'd stretch almost 60,000 miles: twice the earth's circumference.
Governing Your Aerobic Capacity
Your cardiovascular system helps govern your aerobic capacity or VO2 max--the greatest rate of oxygen consumption you can attain during maximal or exhaustive exercise--by limiting your maximum heart rate and your stroke volume, which is the amount of blood your heart pumps each beat, according to Sport-Fitness-Advisor.com. When you perform aerobic exercise, the size of your heart increases, which allows you to increase your stroke volume and pump more blood per beat. Your maximum heart rate does not respond to training by significantly increasing or decreasing, and largely is set. When your heart rate is multiplied by your stroke volume, the resulting value or rate is known as your cardiac output. Along with your total blood volume and your blood's ability to reach your tissues, your maximum cardiac output determines the extent of your aerobic capacity, although some researchers believe that your body's ability to utilize oxygen, not just supply it, is equally important in limiting your aerobic capacity. Proponents of this theory, called Utilization Theory, posit that the amount of oxidative enzymes in your cell's mitochondria or energy factories determine your aerobic capacity.
