For example, skin cells form a stretchy, waterproof covering that protects your body from heat and cold. Muscle cells enable you to move. Other cells make up your nervous system. The biggest part of the nervous system is the brain. Special cells in the brain send information to the rest of your body, telling it what to do.
Bacteria are germs that multiply by splitting into two cells.
Those cells keep dividing. While our body contains many good bacteria, there are some that make you sick. They release poisons and cause the body to react to them. If many bacteria grow and the infected person is not immune, they get sick. Bacterial infections are usually treated by antibiotic drugs.