The heart is the body's hardest-working muscle. Whether you're awake or asleep, or exercising or resting, your heart is ...

Circulatory system: Blood vessels. Laid end-to-end, an adult's arteries, veins and capillaries would stretch for about 100,000 miles - enough to wrap around the world nearly four times.

Learn about the anatomy of the heart and how its chambers, valves, and vessels work together to maintain effective blood circulation throughout the body to sustain life.

Learn about the circulatory system with these interactive learning resources for KS2 Science students aged 7-11 from BBC Bitesize.