The purpose of the heart, and the circulatory system as a whole, is to carry blood to the lungs for oxygen, and then to pump that blood to the body cells. This provides cells with a constant source of the oxygen they need in order to survive. Heart and circulatory diseases, in general, inhibit the ability of the circulatory system to fulfill that purpose, leading to inadequate oxygenation of body cells.
Function
The circulatory system acts like a series of pipes through which fluid flows, driven by a single pump. The pump, or heart, must move blood through the pipes, or blood vessels, efficiently and effectively throughout a person's life. If disease prevents the heart from pumping, the vessels from delivering blood, or the blood from serving its purpose of carrying oxygen to the body cells, the circulatory system fails in its ability to provide cells with the molecules they need to survive. This can lead to a variety of symptoms, up to and including death.
Heart Disease
Some cardiovascular diseases are related to the heart and prevent it from pumping blood effectively. The American Heart Association explains that congestive heart failure is a collective term for any heart disease in which the organ's ability to deliver blood is compromised. Since the heart can't pump blood out at high pressure, the veins that return blood to the heart become filled with fluid. This fluid leaks out of the vessels, leading to swelling of the extremities. Fluid also collects in the tissues of the lungs, producing high pulmonary blood pressure and shortness of breath.
Vessel Disease
Some diseases of the circulatory system are vascular; in some way, they prevent the vessels from delivering blood. MayoClinic.com, for instance, explains that atherosclerosis is a common form of cardiovascular disease in which the vessels become hardened and clogged with cholesterol plaques. This narrows the vessels and hinders blood flow. Further complicating matters, the plaques can tear and bleed, which leads to the formation of blood clots that further narrow vessels and can cause heart attack and stroke.
Blood Diseases
The third important component of the cardiovascular system, the blood, may also be diseased. Sickle cell anemia is a genetic disease in which the protein hemoglobin that forms the red blood cells is misshapen. This, consequently, produces misshapen red blood cells that form clots in small vessels, notes the National Heart Lung and Blood Institute. The damaged blood cells can't carry sufficient oxygen, meaning that even if the heart and blood vessels are completely healthy, the circulatory system fails to achieve its objective. Sickle cell anemia is often treated with blood transfusion and marrow transplant.
Expert Insight
While some circulatory and heart diseases are present at birth, others arise as the result of unhealthy life choices. MayoClinic.com explains that most atherosclerosis and vessel disease is the product of diets high in saturated fat and cholesterol, combined with lifestyles low in exercise. They recommend a low-fat, low-cholesterol diet including plenty of fiber to reduce the risk of vessel disease and resulting circulatory damage. Further, the heart, like any muscle, benefits from regular exercise. This strengthens the heart and allows it to pump blood more efficiently, reducing its workload and decreasing the risk of heart disease.
