Every part of a human's body has cells in it. Our skin has cells. Our hair has cells. Our organs have cells. Some of our cells work all the time, like our heart cells. They pump our blood whether we tell them to or not. Other cells work only when we want them to, like some muscle cells. The cells in our mouths work only when we want to chew food or swallow. Every cell has a special job to do and they know exactly how to do their jobs.
Even though cells have a lot of the same things inside them, they can look quite different.
Humans have about 75 trillion (75,000,000,000,000) cells in their bodies!
Graphic by Blake
Quick Math: If your body has 75 trillion cells, how many cells does your whole class have? (Hint: Multiply 75 x the number of students in your class. Don't forget to add twelve zeroes on the end to get the right answer when you're finished.)
