They produce an oily substance called sebum. It moisturises the skin and stops it from drying out or cracking, which could create an opportunity for germs to get inside our body. Thanks to sebum, our skin  makes it hard for germs to survive on it.

Mucous membranes produce mucus, a sticky substance, which traps germs in the respiratory tract and  kills the intruders.Tiny hairs in our noses also work as a barrier that catches germs.Enzymes are found in tears, saliva and  sweat. They break up and destroy germs.

There are many types of white blood cells. Each type has a specific mission in our body’s defence. Some of them attack bacteria, others produce antibodies or swallow up and digest germs, kill bacteria, fungi, or cancer cells.

Lymph nodes have immune cells. They scan  foreign material which enters our body. After the analysis, they activate and send the right types of lymphocytes to fight the intruders. The increased number of lymphocytes makes the lymph nodes swell, that’s why doctors usually check them to see if they are bigger than usual, as it is a sign of infection.

Tonsils are important in early childhood, later in life, their size becomes smaller and their role is not that important. Tonsils usually become bigger in childhood and cause colds and trouble with swallowing. Doctors can see tonsils when the patient’s mouth is wide open.

A donor’s bone marrow replaces or regenerates the one that isn’t working. It restores its usual function so, thanks to the transplant, the number of blood cells is back to acceptable levels again. Statistics show that only 30% of people can find a matching donor in their families. The remaining 70% must wait for an unrelated person to donate their bone marrow.

It’s important to pay attention to what we eat, as it affects the number of  different bacteria in the gut. Eating plant foods that are high in fibre is very good for us, while eating probiotic‑rich foods like kefir or sauerkraut brings the balance back after your body has been exposed to bacterial infection.

It is still unknown why our immune system may react in such a way. Some autoimmune diseases run in the family, while others are caused by other factors. There is no definite cure, so treatment for autoimmune diseases generally focuses on minimising immune system activity.

Antibiotics must be used in the right way. Taking the wrong antibiotics or taking them “just in case” can lead to antibiotic resistance. It means that the antibiotics used will not be effective in the future so it will be harder to treat the infections caused by that specific type of bacteria. It also means higher medical costs, longer stays in hospitals and higher mortality. Unfortunately, without a major change, they will continue to be over‑prescribed by doctors and over‑used by the public.

Not all people can be vaccinated. Some of them may have health problems or allergies which make it impossible for them to get such protection. However, they may be protected if they live in an environment where most people have been vaccinated. It is a lot harder for a virus to spread then. The more vaccinated people there are around, the less likely it is to be exposed to the dangerous virus.

Staying positive and laughing out loud can also make your immune system work better. According to studies, one minute of anger weakens the immune system for 4 to 5 hours. On the other hand, one minute of laughter boosts the immune system for 24 hours. Scientists don’t know, however, if it means less illness for a longer period. Another way of helping your immune system is to get a dog or some other furry pet, as they can help your immune response and make you less likely to get allergies.