The heart and blood vessels constitute the cardiovascular (circulatory) system. The heart pumps the blood to the lungs so it can pick up oxygen and then pumps oxygen-rich blood to the body. The blood circulating in this system delivers oxygen and nutrients to the tissues of the body and removes waste products (such as carbon dioxide) from the tissues.
Sometimes, medical history and physical examination alone suggest to a doctor that the person has a heart or blood vessel disorder. However, special diagnostic procedures are often needed to confirm the diagnosis, determine the extent and severity of the disease, and help plan treatment.
The aorta, which is about 1 inch (2.5 centimeters) in diameter, is the largest artery of the body. It receives oxygen-rich blood from the left ventricle and distributes it to all of the body except the lungs (which receive blood from the right ventricle). Just after the aorta leaves the heart, smaller arteries that carry blood to the head and arms branch off. The aorta then arches down, with additional smaller arteries branching off along its route from the left ventricle to the lower abdomen at the top of the hipbone (pelvis). At this point, the aorta divides into the two iliac arteries, which supply blood to the legs.
Atherosclerosis is a condition in which patchy deposits of fatty material (atheromas or atherosclerotic plaques) develop in the walls of medium-sized and large arteries, leading to reduced or blocked blood flow.
Cardiac arrest is when the heart stops pumping blood and oxygen to the brain and other organs and tissues. Sometimes a person can be revived after cardiac arrest, particularly if treatment is started immediately. However, the more time that passes without oxygen-containing blood being pumped to the brain, the less likely it is that the person can be revived, and, if revived, the more likely it is that the person will have brain damage.
Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or other changes that may further weaken or stiffen the heart.
Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has a one-way "in" (inlet) valve and a one-way "out" (outlet) valve. Each valve consists of flaps (cusps or leaflets) that open and close like one-way swinging doors.
The lymphatic system is a vital part of the immune system. It includes organs such as the thymus, bone marrow, spleen, tonsils, appendix, and Peyer patches in the small intestine that produce and process specialized white blood cells that fight infection and cancer.
Athlete's heart refers to the normal changes that the heart undergoes in people who regularly do strenuous aerobic exercise (for example, higher intensity running or bicycling) and also in those who do higher intensity weight training exercise (weight lifting).
Veins return blood to the heart from all the organs of the body. The large veins parallel the large arteries and often share the same name, but the pathways of the venous system are more difficult to trace than those of the arteries. Many unnamed small veins form irregular networks and connect with the large veins.