What are the differences between bacteria and viruses?
Bacteria are tiny organisms made up of one single cell, and exist virtually everywhere, both inside and on our bodies. The human mouth, for example, is home to more than 500 species of bacteria. While some bacteria cause disease, most of them are completely harmless or even useful. Bacteria can reproduce themselves by cell division.
Viruses, on the other hand, are much smaller and harmful. A virus is not even a cell – it is just a DNA or RNA molecule surrounded by a protein shell. They exist only to reproduce themselves, something they cannot do on their own. Instead, they need to invade a host cell and take over its replication machinery in order to reproduce. Usually, this process also destroys the cell…
What causes common cold?
Colds are caused by infection with one of about 200 different viruses. Most often it is a type of virus called rhinoviruses. People with a cold have runny noses with plenty of viruses, which spread from person to person by droplets that come from coughing or sneezing. The first line of defense against viruses is your skin – the viruses cannot penetrate it! In order to infect you, they must come into your body somehow. You can catch a cold by inhaling virus-containing droplets, for example if you are sitting next to a person who sneezes. A more common way of getting a cold, however, is that you touch your face after you have touched something that is contaminated by the virus, for example by shaking hands with someone who has a cold or grabbing a phone that has been used by someone who is infected. Then the virus can enter through the mouth, the nose or the eyes. Just think about it – how many times a day to you touch your face?
What are the symptoms all about?
When you are infected with a virus, it causes a massive response from your immune system – your body’s defense against foreign substances and organisms. This includes the “soldiers” of the immune system, the white blood cells, which are sent in large numbers to the area of infection. It is not the virus itself, but the reaction from the immune system that makes us feel ill.
Coughing is your body’s way of getting mucus out of your system. The mucus is produced as the white blood cells attack the virus-infected cells. The quicker you get it out, the quicker you’ll be feeling better.
Sneezing happens when the soft lining of the nose or throat becomes irritated. When you sneeze, your body attempts to clear out whatever causes the irritation. If you blow your nose, you might get rid of the irritants without sneezing.
A blocked nose is not due to excess of mucus – it happens because the veins in your nose are inflamed. When the cold virus get into your nose, a molecule called histamine is released and that causes the blood flow to the nose to increase. Then the nose begins to swell up…
A runny nose is another way that your body tries to get rid of the virus. The mucus is clear in the beginning, but as the cold develops it becomes thicker and yellow. This happens because the number of white blood cells that flood to the nose increases. A runny nose is really not that bad – your body gets rid of plenty of virus!
Most popular game
You are a virus infecting humans. Survive by making your human host sneeze at the right time at the right place, infecting other humans!
Use arrow keys to move your human host. Press space bar to sneeze. You can only sneeze once on each level, so choose your sneeze carefully! To level up, infect a certain percentage of the people on the screen.
This game does not save highscores - if you get a good score, write it in the Discussion section!
Article by Per Thorén, Chalmers University of Technology, Sweden