Cardiovascular system
The body system of the heart and blood vessels that circulates blood, delivering oxygen and nutrients to tissues and carrying away wastes.
Heart: A muscular organ that pumps blood through the lungs and the rest of the body. Its chambers and valves generate the pressure that drives circulation.
Blood: A circulating tissue composed of plasma, red and white blood cells, and platelets. It transports gases, nutrients, hormones, wastes, and immune components.
Electrocardiography: The recording of the heart's electrical activity using electrodes on the body. Its traces help identify rhythm disturbances and signs of cardiac injury.
Lymphatic system: A network that returns tissue fluid to the bloodstream and supports immune defense. Unlike blood circulation, it has no central pump and carries lymph in one direction.
Oxygen transport: The movement of oxygen from the lungs to body tissues, primarily bound to hemoglobin in red blood cells. Cardiac output and blood flow determine how quickly oxygen reaches working tissues.
Blood vessel: A tube that carries blood through the body, including arteries, veins, and capillaries. Vessels distribute blood, exchange materials with tissues, and return it to the heart.
Artery: A blood vessel that carries blood away from the heart. Its muscular, elastic wall withstands pressure from ventricular ejection.
Echocardiography: An ultrasound examination that images the heart and measures its motion and blood flow. It reveals structural and pumping abnormalities without surgery.
Open circulatory system: A circulatory arrangement in which circulating fluid leaves vessels and bathes organs directly. It contrasts with vertebrate circulation, where blood remains within a closed vessel network.
Coronary circulation: The blood flow through vessels that supply the heart muscle. The heart depends on its own circulation to sustain continuous pumping.