Read the text describing what happens inside your body when it fights a disease.

Agnieszka Sękiewicz‑Magoń The Silent Heroes Inside Your Body

At every moment of your life you are exposed to bacteriabacteria [bacterium]bacteria, virusesviruses [virus]viruses, parasitesparasites [parasite]parasites and fungifungi [fungus]fungi, which look for ways to get under your skin. They may do so through a cut, with food you eat or when you touch something and then rub your eyes. Luckily, your body has a powerful weaponweaponweapon to protect you from foreign invadersinvaders [invader]invaders. It is called the immune systemimmune systemimmune system.

The first line of defencedefencedefence includes your skin, tears, mucusmucusmucus, stomach acidstomach acidstomach acid, urineurineurine, “good” bacteria and white blood cellswhite blood cellswhite blood cells.

Your skin is a natural barrier between pathogens and your body, so they cannot get through it unless it is broken. Tears, mucus and salivasalivasaliva contain a special enzyme which weakensweakens [weaken]weakens many bacteria so that they are either killed or trapped and cannot travel any further. Even if they somehow manage to get through and are swallowed, they will be killed by stomach acid, beneficialbeneficialbeneficial bacteria in your intestinesintestines [intestine]intestines or they will be flushed from your organism with urine.

However, it is white cells, also called leukocytes, which are the biggest heroes of the immune system, even though they constituteconstituteconstitute only 1% of total blood cells and live from 1 to 3 days. They find and kill pathogens that want to enter your body.

What does the whole process of fighting a disease look like? Well, once the unwelcome guests are inside, your organism responds. It is visible in swellingswellingswelling of your lymph nodeslymph nodes [lymph node]lymph nodes, high temperaturehigh temperaturehigh temperature and painpainpain that you feel. You shouldn’t worry, though. These are signs that your immune system is working hard to get rid ofget rid of get rid of the infection. Your white cells surround and destroy the dangerous substances, called antigensantigens [antigen]antigens, which attack a part of your body. The raised temperature makes it harder for germs to survive in your body and the pain that you feel is caused by the inflammationinflammationinflammation, leaving the muscles in your body achyachyachy and stiff.

If the first barrier of cells is not enough, our organism produces antibodies which also fight the enemy cells. Additionally, they keep in memory anything they have attacked, so you gain some sort of immunity toimmunity toimmunity to a given disease.

The problem with viruses or bacteria, however, is that their survival relies on their adaptabilityadaptabilityadaptability to constantly changing environments, so they mutatemutatemutate. Their mutation ratemutation ratemutation rate is so high that sometimes antibiotics are not effective enough in their help to fight the disease. This is also the reason why you have to get some vaccinesvaccines [vaccine]vaccines every year, (such as flu vaccines) as the viruses causing the disease may be different from season to season. VaccinationvaccinationVaccination is important, because it helps your body develop immunity to a given disease by imitating an infection. Usually, you only experience some minor symptomsminor symptoms [minor symptom]minor symptoms such as feverfeverfever, but, in return, your body remembers how to fight the disease in the future.

1 Źródło: Agnieszka Sękiewicz‑Magoń, licencja: CC BY-SA 3.0.