You can count numbers all around you, from the eight legs on a spider to the one nose on your face. But can you count the stars in the sky or the fish in the Amazon? Find out all about the THE HUMAN BODY in THE BIG COUNTDOWN, including the millions of bacteria that live in and on us and help our body function healthily, our digestive system, our bones and muscles, our blood and heart, our lungs and breathing, the size of our brain and the number of hairs on our head. It also covers the human life cycle and the development of a foetus in the womb.

The Big Countdown looks at popular topics and investigates the great many numbers that make them fascinating. From the mind-bogglingly large to smallest and most precious, this series helps us understand that it's not just our days that are numbered.