Circulatory system: The transport system of an animal, made up of the heart, blood vessels and blood, that moves substances such as oxygen, nutrients and wastes around the body.
Transport system: A system of vessels and a pump that carries dissolved substances and cells to and from all parts of an organism.
Single circulation: A circulatory system, as in fish, in which blood passes through the heart only once for each complete circuit of the body.
Double circulation: A circulatory system, as in mammals, in which blood passes through the heart twice for each complete circuit of the body, keeping oxygenated and deoxygenated blood separate.
Advantage of double circulation: Blood can be pumped to the body at higher pressure, allowing faster delivery of oxygen and nutrients than a single circulation can provide.
Pulmonary circulation: The loop of the double circulation that carries blood from the heart to the lungs and back to the heart.
Systemic circulation: The loop of the double circulation that carries blood from the heart to the rest of the body and back to the heart.
Heart: A muscular organ that pumps blood around the body by repeated contraction and relaxation.