Your circulation is the system of tubes called blood vessels which carries blood out from your heart to all your body cells and back again.
Blood circulation was discovered in 1628 by the English physician William Harvey (1578-1657), who built on the ideas of Matteo Colombo.
Each of the body’s 600 billion cells gets fresh blood continuously, although the blood flow is pulsating.
On the way out from the heart, blood is pumped through vessels called arteries and arterioles.
On the way back to the heart, blood flows through venules and veins.
Blood flows from the arterioles to the venules through the tiniest tubes called capillaries.
The blood circulation has two parts – the pulmonary and the systemic.
The pulmonary circulation is the short section that carries blood which is low in oxygen from the right side of the heart to the lungs for ‘refuelling’. It then returns oxygen-rich blood to the left side of the heart.
The systemic circulation carries oxygen-rich blood from the left side of the heart all around the body, and returns blood which is low in oxygen to the right side of the heart.
Inside the blood, oxygen is carried by the haemoglobin in red blood cells.