The body is constructed from
trillions of tiny living units,
known as cells. There are more
than 200 different types of cells –
and each has its own shape, size,
and specific job to do. Typically,
cells of the same type work
together in units called tissues.
Each individual cell is surrounded
by a thin membrane that regulates
the movement of nutrients and other
substances in and out of the cell. Cells
multiply by continually dividing
into two identical “offspring”. This
division allows the body to grow
and to replace cells that are
damaged or worn out.CELLS
62
A macrophage
“reaches out” to
capture bacteria
(blue), which it will
then digest12062_063_Cells.indd 62 03/01/19 12:09 PM