A cell is the littlest basic and useful unit of a living being. A few creatures, similar to microscopic organisms, comprise of just a single cell. On the outside, they look very different, but if you look close enough you’ll see that their cells are actually very similar.
In all cases, cells just originate from cells that have existed some time recently. This idea led to the development of one of the most important theories in biology, the cell theory.
Cell theory states that:
All organisms are composed of cells.
Cells are alive and the fundamental living units of association in all creatures.
All cells come from other cells.
Nerve cells are long and stringy in order to form a line of communication with other nerve cells, like a wire. Because of this shape, they can quickly send signals, such as the feeling of touching a hot stove, to your brain.
Skin cells are flat and fit tightly together to protect your body.