According to Estrella Mountain Community College, the circulatory or cardiovascular system consists of the heart, blood vessels and blood. These three components work in concert to maintain the body's cellular processes and keep a person healthy and vital. Aerobic exercise training can improve the health and efficiency of the cardiovascular system, promote longevity and reduce the risk of chronic disease.
Heart
The heart proves the most important part of the cardiovascular system. According to the Texas Heart Institute, the heart weighs between 7 and 15 ounces, proves slightly larger than the size of a person's fist and is extremely resilient. The typical human heart beats approximately 100,000 times per day and pumps about 2,000 gallons of blood. Centenarian's hearts may have beat over 3.5 billion times. The heart is situated between the lungs in the middle of the chest, behind and just to the left of the breastbone or sternum. A double-layered sac, called the pericardium, surrounds the heart. The pericardium's outer layer is attached to the spine, diaphragm and other parts of the body by ligaments. The pericardium's inner layer is attached to the heart itself. Between the pericardial layers is a coating of fluid that allows the heart to move while it beats, yet remain attached to the body.
Blood Vessels
Blood vessels remain another important part of the cardiovascular system. According to the American Heart Association, if the body's blood vessels were laid end-to-end, they would stretch for 60,000 miles or twice the earth's circumference. Blood vessels are elastic tubes that carry blood and its constituents to the various cells, tissues and organs that compose the human body. The several types of blood vessels include arteries, arterioles, capillaries, venules and veins, with blood leaving the heart flowing through these vessels in that particular order. Arteries remain the strongest blood vessels while arterioles, smaller diameter blood vessels, prove the principle site of vascular resistance to arterial blood flow and help dictate blood pressure. Capillaries are the body's smallest blood vessels and are the location where gases, nutrients and waste products exchange with the cells. Venules are tiny blood vessels that help deoxygenated blood return to the veins, and the veins, in turn, send blood back to the heart.
Blood
Blood remains the final component of the cardiovascular system. According to the KidsHealth website, blood supplies the body's organs with the oxygen and nutrients they require for survival, and without blood, a person would not be able to thermoregulate, battle infections or eliminate cellular waste products. Blood contains plasma--a yellowish fluid consisting of 90 percent water, along with nutrients, proteins, hormones and waste products--and three types of blood cells, including red blood cells, white blood cells and platelets. As children, blood cells are generated in the bone marrow of numerous bones throughout the body, but as people age, blood cell production primarily occurs in the vertebrae, ribs, pelvis, skull, sternum and parts of the humerus and femur. Blood flow always remains constant to the brain, but other organs and body parts receive blood based on physiological demands.
