Nina investigates why people have blood in their bodies, with the help of Luke, her sight neuron.

Experimenters Gary, George and Ryan visit Nina in her lab and discover that there is lots of blood inside everyone. The blood travels to every part of the body, from the tops of the head to the tips of the toes, inside lots of little, tiny tubes. Blood does this because it is carrying lots of important things around the body, a bit like a delivery driver. One of these important things is a gas called oxygen which the body uses to do lots of important jobs.

The Experimenters visit a go-kart track and have lots of fun pretending to be red blood cells delivering oxygen around the body. Back in the lab, they do an experiment and discover that people also have white blood cells in their blood. These do the important job of destroying nasty germs that could cause an infection and make people ill. Show less