Our fifth and final subject for study in the series is the cells, the basic building blocks of our bodies. There are an awful lot of them, about 40 trillion (million million), with a mere 35 billion, thousand million, skin cells, and around two billion cells in our hearts.
There are about 200 different kinds of cell, including blood, muscle, skin, nerve, glandular cells, etc. Half our cells are taken up by red blood cells.
