How Does The Immune System Work? (Basic Explanation)
First, the intruder must enter through an opening in the body or a wound. But each opening is well protected. For example, mucus traps intruders, tonsils contain macrophages (cells that engulf intruders) and tears kill bacterium. Anyways, since there are so many ways you can get infected and the bodies defence is different for each case, I'm going to talk about bacterium that enter the body through wounds and cause tissue infections.
The bacterium that enters the body will start multiplying and won't cause damage. But after the number of bacterium inside the body has increased by quite a number, they will change altitudes and start invading the cells. Luckily, macrophages ( which are big cells which can devour up to a 100 intruders before undergoing apoptosis ) come in and start killing the bacterium. They trap the bacteria in a membrane and use enzymes to kill the bacteria.
But if that isn't enough to stop the infection, the macrophages alert blood vessels to release liquid which makes fighting easier. This is when you start feeling some of the symptoms of a tissue infection. They also alert neutrophils which fight more furiously and release toxic chemicals. They also kill healthy body cells in the process. In order not to cause to much harm, they undergo apoptosis quicker than macrophages.
If that still isn't enough, dendritic cells come in and will collect samples of intruders. After that, it goes to the nearest lymph node to activate the T-cells designed to attack that intruder there. It will then go to activate the B-cells that are also designed to attack that same intruder. But the T-cells must also travel to the B-cell to activate it to make sure the B-cell isn't counterfeit. Unless, of course the T-cell is also counterfeit. This may cause the infection to be worse. The T-cells then start multiplying. Some become memory T-cells ( MTCs ). Some become helper T-cells ( HTCs ) which activate B-cells and makes the other cells work harder. The rest also help in the fight. B-cells also multiply into memory cells. The rest will turn into antibody factories which stun bacterium and prevent them from invading cells.
Also, there are natural killer cells that kill infected cells and the intruders inside. After that the infection should be wiped out in a few days. Unless the intruders are immune or infected the B-cells and natural killer cells. This will cause the body to release a cytokine storm which is when all the immune cells target on that particular species of invaders. That would almost definitely wipe out the infection. But that would have also hurt your body a lot. So technically, the stronger your immune system, the more damage it can do to you.
So that is the end of my explanatory report. But this is just a simplified version and of a specific invasion. There are many more immune cells out there I didn't talk to you about. This would also have been a lot longer if I explained a bit more in depth and had all the definitions of words that you probably didn't know. Anyways, I hope you liked my report about the immune system. The End
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