cardiovascular system

The cardiovascular system is the heart plus the vast network of tubes — arteries, veins and tiny capillaries — that carry blood everywhere it needs to go. Picture a pump connected to thousands of kilometres of branching pipes, delivering fresh supplies to every street in the body and hauling waste away.

Its job is transport: it moves oxygen, nutrients, hormones, immune cells and heat to the tissues, and carries carbon dioxide and metabolic waste back to the lungs and kidneys for removal. The heart provides the pressure, the arteries distribute blood under that pressure, capillaries are where exchange with tissues actually happens, and veins return blood to the heart.

The term cardiovascular literally joins cardio (heart) and vascular (vessels), signalling that the heart and the vessels are one integrated system, not two separate things. A problem in one part — a stiff vessel, a blocked artery, a weak pump — ripples through the whole network.