Cells come in many shapes

Cells of the same body can look very different. A human muscle cell is shaped like a spindle, thick in the middle and pointed at both ends. A nerve cell is very long, with branches. Some cells are round, others long and thin, and the number of cells differs from one living thing to another.

Why so different? Because a cell's shape, size and structure fit the job it does.

Picture the nerve cell this way. If you had a very long arm with many fingers, you could tap several friends across the room at once. Without it, you would have to walk over to each one first. A long, branched nerve cell reaches distant parts of the body and passes messages on fast.

Plant cells vary too: they can be rectangular, long, oval or even tube-like.

You saw this at work in Grade 7. Muscle cells in the food pipe contract and relax in a wave, squeezing food down to the stomach. They can do it because they are thin, flexible and spindle-shaped.

The stomach uses different cells for different jobs. Muscle cells in its wall churn the food. Other cells in its lining make the digestive juices and acid that break food down. All of them work together.