Getting sick is possibly the least fun thing that can happen to you... it's even worse than getting pulled over by the cops with expired registration or meeting the President with a big piece of spinach stuck in your teeth. But what really happens when you get sick? Mystery solved. Your immune system is @$% amazing and it does all kinds of stuff to boot out those invaders that are willing to move in and wreck all your cells and then die before you can get your deposit back. Seriously. Immature jerks.
http://www.ranker.com/list/10-things-that-happen-when-you-get-sick/analise.dubner,
Body Temperature Rises
First off, in almost all cases, a fever is not bad. It's our own immune system utilizing another weapon in its arsenal. Lots of times, a low-grade fever you probably never even noticed killed off an invader before you even started to feel sick. When the fever increases, it's because it's working harder to kill whatever intruder is replicating inside you.
The worst - muscle aches with fever. This happens because of chemicals released to fight the invader tend to cause inflammation in muscles and joints, and often muscle enzyme levels are elevated in the blood as a result of this. Ow. When antibodies bind to the virus or bacteria they deactivate it and make it more easily digestible to white cells. However, this process causes inflammation and tissue irritation.
Many times, running to the fever-reducers, like ibuprophen and aspirin, is totally effing up all the hard work your immune system is doing. Imagine if you kept trying to turn on the heat because the apartment was cold, and your boyfriend would walk in and turn it down every time you left the room. Annoying, right? Well, in this case you're just making things worse... because your body is trying to kill that damned bug and you're not letting it. So... just relax and let the fever work its magic. Only when the infection is super-bad and your fever goes out of control? Then you can try to reduce it.
The Battlefield
Why do you get a runny nose? A sore throat? Cough? Why do your muscles ache and why do you get those hard, swollen lumps under your jaw along your neck?
War, baby.
Runny nose? Your body increases the production of mucus to try and clear out the invaders. It usually shows up 3-5 days after your initial infection and you can tell if it's just normal cleanup of the cold or, if it turns green and thick - it can be a sign of a bad bacterial infection.
Your sore throat happens when the mucus membranes that line your throat are either inflamed or infected. Your immune system sends a lot of blood into that area so that the white blood cells and antibodies have more access to the battlefield. The side-effect is that in order to get more soldiers into the area, your body releases chemicals that make the blood vessels in the surrounding tissue swell. More blood = more white blood cells and more antibodies. Sadly for you, all this swelling puts pressure on the nerve endings in your throat and causes pain. War is tough.
Coughing... well, mucus is an irritant, and coughing is a natural reaction to irritation. What's the most insidious is that it's thought that making us cough is actually the evolutionary strategy of the virus to escape from us and move on to the next victim. We know that cold and flu viruses are spread by airborne droplets of mucous spewed out when we cough.
And swollen lymph nodes? Think of Lymph nodes like a filter. When fighting certain bacterial infections, the nodes swell up with bacteria and the cells fighting the bacteria, to the point where you can actually feel them. Swollen lymph nodes are a good indication that you have an infection of some sort.
Antibodies Deploy!
Antibodies are pure awesome. These amazing little guys are produced by white blood cells. They are Y-shaped proteins that each respond to a specific invader (bacteria, virus or toxin).
Each antibody has special sections at the tips of the Y that are sensitive to a specific antigen. When an antibody binds to the outer coat of a virus or a bacterium it can stop their movement through cell walls (like putting those mittens on kids to keep them from scratching chickenpox). A large number of antibodies can also swarm and stick to an invader, signaling to a component system that the invader needs to be removed.
License to Kill
NK cells, or natural killer cells, to the rescue! Killer cells are are a type of lymphocyte (white blood cell). They contain special proteins such as perforin and proteases known as granzymes.
When they are let loose near an infected cell slated for death, perforin creates holes in the target cell through which the granzymes can enter, inducing apoptosis. Apoptosis leads to destruction of the virus inside. This can contain and minimize the viral infections while the rest of your immune response is generating antigen-specific T cells that can clear the infection.
T cells are another kind of lymphocyte that plays a large role in the immune response. T cells recognize the invader and bind to it - an action that stimulates the T cell to either destroy or cure the infected cell.
Outer Defenses
You might only get sick once or twice a year, but that's because your immune system is on constant alert. There are many defenses that germs have to penetrate in order to get inside where they can wreak the most damage.
Tears and mucus contain an enzyme that breaks down the cell wall of many bacteria. Saliva is also anti-bacterial. Since the nasal passage and lungs are coated in mucus, many germs not killed immediately are trapped in the mucus and soon swallowed. Mast cells also line the nasal passages, throat, lungs and skin. Your skin, in fact, does more than you realize to keep you safe. Think about it, why doesn't mold grow all over you every night when you sleep? Natural defensive patrols on your skin keep bacteria from growing where it does not on that pear you left on the counter last night.
Any bacteria or virus that wants to gain entry to your body must first make it past these defenses.
How You Can Help Your Immune System
While there's nothing we can currently do to fight cold and flu (at least those strains our bodies haven't encountered yet) because of how quickly they mutate into new, unrecognizable forms, there are other things we can do to fight viruses and bacteria our bodies have fought before.
Vaccines are a weakened form of a disease. It is either a dead form of the disease, or a similar but less virulent strain. Once you take the vaccine, your immune system engages in its usual defense, but because the disease is different or weaker you will get few or no symptoms of the disease. Then, when the real disease invades your body, your body is able to eliminate it immediately.
Keep in mind that a flu shot does not keep away the flus you didn't just get a shot for. There are often many strains running around at all times, so if you get a shot, and then get sick anyway... that's because you were just infected with a totally different strain than that you just got a shot for. Nothing wrong with getting the shot, just keep in mind that you are only getting the bits of viral clues that the shot has, and not ALL the strains dancing around on the push bar of your shopping cart at the grocery store.
Your immune system might remember every face it ever beats into a pulp... but if it doesn't recognize the guy in the Nixon mask when it comes through the front door... it might not attack in time.
Antibiotics, as mentioned earlier, only work on bacterial infections. They have their problems... mostly in that they have been over-prescribed over the course of the last few decades. This has caused a large number of bacteria to become immune to the antibiotics we have. Even new ones we come up with... bacteria seem to be getting around them quicker and quicker. Scientists have speculated that we may be creating our own monstrous, upcoming epidemic... simply because of how MUCH antibiotic we use in our everyday lives.
The Aftermath
Something good came of that cold or flu you just battled. As you lie there on the couch, surrounded by a field of nasty tissues and sweaty blankets... just think. Whatever monster you just battled, you will never battle again. If that invader shows his face on your doorstep again... POW. Your bouncers have his photo posted by the door. They know every detail of its mucus-y face.
Our amazing immune system keeps a record of every microbe it has ever beaten down like a bitch. This means it can destroy it quick and fast, like Robocop, if it enters the body again, and before it can multiply and make you feel sick.
But there will always be new strains - because these guys are tenacious and adaptive, and they never stop trying. It's their job to invade, and damnit, they're gonna do it.
Different Kinds of Invaders
There are two basic kinds of enemies your body is on the lookout for (there are others - like allergens and toxins, but these two are the ones that give you your standard cold and flu).
Bacteria are single-celled organisms that are much simpler than your own fancy cells in that they have no nucleus. Bateria are alive, and are completely independent organisms able to eat and reproduce - sort of like mini fish swimming in your body. Under the right conditions, one bacteria can divide into two separate bacteria perhaps once every 20 or 30 minutes. At that rate, one bacteria can become millions in just a few hours.
The kinds of wonderful things bacterial infection causes? Acne, food poisoning (E. coli, Salmonella, etc), Leprosy, Tonsillitis, eye styes, Pneumonia, Tuberculosis, Staph infections and Lyme disease. Bubonic Plague and Smallpox were both bacterial.
A virus is different. A virus is not really alive, it is nothing but a fragment of DNA in a protective coat. The virus comes in contact with a cell, attaches itself to the cell wall and injects its DNA into your cell. The DNA uses the machinery of your own cell to reproduce new virus particles - particles that are released to invade more cells. A virus turns your own cells into mini-copy machines to replicate itself into a vast army.
Viral infections include: Rabies, Chickenpox, influenza, Herpes, HIV/AIDS, HPV, infectious mononucleosis, Mumps, Measles, Rubella, Shingles, gastroenteritis (stomach flu), Viral hepatitis, Viral meningitis, and Viral pneumonia.
Replication Begins
As far as the virus is concerned - and think of it like a Terminator, since it's not really alive - the purpose of replication is simple. Just survival. No longer term goals. By makin' copies of its genome and packing those copies into viruses, it is able to continue infecting new hosts.
Now, bacteria is different. Bacteria is not only a living organism, it carries all the tools it needs for growth and multiplication and it can reproduce on its own, asexually. In case of sexual reproduction, certain plasmids' genetic material can be passed between bacteria. Most kinds of bacteria are harmless and some are even helpful... the bacteria in our intestines - for example - are very helpful in aiding digestion.
An important thing to note about the difference between these invaders - antibiotics will only work on bacterial infections. Viral infections? Dump every antibiotic known to mankind down your face hole - it will do nothing. (Actually, don't do that - overuse of antibiotics is a real and growing problem).
You Meet the Invader
Hi, virus or bacteria. Why are you looking at me like that?
So, it happens. And it happens all the time, trust me. Sometimes invaders get past your outer defenses and -usually- embed in your throat. What happens next? If it's a known criminal that's been in you before, your body already has the cure. You won't even notice that you've been invaded because the invader will be put down so hard, it won't have time to call for its mommy. Our bodies store the keys to unlocking and destroying any virus it's ever previously met.
But if it's new... or mutated enough that our security system doesn't quite recognize it? Well, then Virus particles or bacteria begin to wage war on the cell lining of your throat (if they entered through your mouth) and the mucus membranes often become inflamed and infected as those first casualties start to pile up. How does your body respond to this attack? It sends an increased flow of blood to these membranes. A higher volume of blood helps send forth a greater army of antibodies and white blood cells, which are the foot soldiers of your immune system.