How does our blood circulate
Blood is pumped in a continuous flow from the heart. Blood flows inside a network of tubes called Blood vessels – arteries, veins and capillaries.
The Blood in arteries comes straight from the heart and it pumped under pressure, so the artery walls are thick and muscular. Blood moves from arteries to veins through tiny capillaries, which are about one-tenth the thickness of a human hair. Capillaries are so narrow that red blood cells have to squash themselves up to pass through. Veins return Blood to the heart, and because the pressure is lover. They have thinner walls than arteries.