What is a virus, and how does it make you sick?(PDF version) Cells are the tiny building blocks of all plants and animals. Your body is made up of many, many cells: skin cells, blood cells, bones cells, and many others—much like the way this sculpture of Albert Einstein’s face is made up of Legos—only much, much smaller. How small are they? To get some idea, go to Google and ask: “How many cells are in a human body?” Now imagine dividing your body up into that many pieces: that’s how small cells are. The cells in your body don’t live forever. Because they don’t live forever, the cells in your body make new cells all the time. After a while, the old cells die and the new cells replace them. Then the new cells make more cells for a while, and then they become old and die. The cycle goes on and on as long as you are living. How long do the cells in your body live? To find out, go to Google and ask: “How long do blood cells live?” Now ask: “How long do skin cells live?” 3) Skin cells live for about: _________________________________ DNA: How to make new cells. In order to make new cells, every cell in your body has the instructions it needs to make them. Image 1 I might say: “Put the yellow block on top of the blue block. Then put the green block on top of the yellow block . . .” and so on. Cells have their own set of instructions. But the instructions don’t tell the cells how to build a tower, they help the cells make new copies of itself. Skin cells make new skin cells. Heart cells make new heart cells. These instructions are called DNA, and they are found inside every cell. What is a virus? A virus is a tiny bundle of instructions for making new viruses. How tiny is a virus? Ask Google: “How tiny is a virus?” A virus is so tiny that, if you were as small as a cell, you would still need a microscope to see a virus. Here are some drawings of different viruses: Image 2 Image 3 How does a virus make you sick? When a virus enters your body, it finds a cell and changes the instructions inside that cell. Imagine if someone took the instructions to build the block tower (Image 1) and changed them to read “Put the red block on top of the blue block. Then put the yellow block on top of the red block . . .” The tower might look like this: Image 4 The virus does something like that to the cell. The new instructions tell the cell to stop making new cells and start making copies of the virus. The cell may end up making 1,000s of new copies of the virus. These new copies can go on to take over other cells. Your body fights back. Your body can usually tell when a virus has taken over some of your cells, and it starts making special cells, called “antibodies” to chase the virus out of your body. The antibodies cover the virus with liquids, and you “chase” the virus away by coughing and sneezing these tiny drops of liquid out of your body. So when you cough or sneeze you have to be careful that these little drops don’t land where someone else might touch them, because these drops have the viruses in them. Your body often starts making itself very hot when you have a virus. This is your body’s way of trying to “cook” the virus. It’s trying to dry out the virus so that the virus falls apart and can't hurt you. We call this a fever when this happens. When this happens, remember that your body is trying to help you. It is trying to kill the virus and remove it from your body so that the virus can’t take over any more of your cells. You might feel bad when your body is fighting a virus, but hopefully you will feel better soon after your body has finally gotten rid of the virus. (PDF version) If you have MS Word on your computer, you can open the lesson sheet and type your answers right on the sheet. Then, if you want, you can send it to me at gsimonelli@leffellschool.org as an email attachment and I will read what you wrote. If you do not have MS Word, you can download and print the PDF version. You can write the answers on the paper, but I won’t be able to see what you wrote. Don’t worry about that. Either way is okay. |