Hurrah, we come to the end of the module! We started by wondering how the nutrients in the food we eat reach the trillions of cells. The answer is: blood. Blood carries nutrients and oxygen to each cell of the body.
The blood vessels cover a lot of length in the body. A LOT! If you took all the blood vessels in a human adult, and connected them end to end, the total length would be 1 LAKH KILOMETRES!
We need such a large network so that the nutrients we produce in the small intestine reach all parts of the body.