Germs and immunity
Germs and immunity: a chapter of The Human Body Book, with the facts about your own body that are worth knowing.
11 cards · Science
Each Zap teaches up to 5 new cards, so you learn the chapter a few at a time.
Checked by the Brain Zap team · reviewed 27 Oct 2026
Sources: Human body (Encyclopaedia Britannica), Health A to Z (NHS)
Preview
The body's first barrier against germs
Show answerHide answer: The body's first barrier against germs
Skin
Learn more: Unbroken skin keeps most germs out, which is why cuts need cleaning.
Y-shaped proteins that latch onto germs
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Antibodies
Learn more: Each kind fits one germ's shape and marks it for destruction; some stay ready for years.
Marker on a germ that the immune system spots
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Antigen
Learn more: Vaccines show your body an antigen safely, so it learns to recognise the real germ.
Why the body raises its temperature in an infection
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To slow germs down
Learn more: A fever makes it harder for many germs to multiply and speeds up some immune cells.
Colds and flu are caused by these, so antibiotics fail
Show answerHide answer: Colds and flu are caused by these, so antibiotics fail
Viruses
Learn more: Antibiotics work on bacteria; taking them for a cold doesn't help and breeds resistant bacteria.
About this topic
Germs try to get in every day, and your body has layers of defence. Skin keeps most of them out, lymph nodes filter them, and antibodies latch onto the ones that get through. A fever slows them down, and vaccines teach your immune system to recognise a germ before you ever meet it. This chapter also covers why antibiotics don't work on colds, how herd immunity protects babies, and the doctor who first asked colleagues to wash their hands.
This is a chapter of The Human Body Book. Each card asks one question, with a hint before you answer and a short reason after. Once you know most of this chapter, the next one starts arriving in your Daily Zap.
All 11 cards
The body's first barrier against germs
Skin
Learn more: Unbroken skin keeps most germs out, which is why cuts need cleaning.
Y-shaped proteins that latch onto germs
Antibodies
Learn more: Each kind fits one germ's shape and marks it for destruction; some stay ready for years.
Marker on a germ that the immune system spots
Antigen
Learn more: Vaccines show your body an antigen safely, so it learns to recognise the real germ.
Why the body raises its temperature in an infection
To slow germs down
Learn more: A fever makes it harder for many germs to multiply and speeds up some immune cells.
Colds and flu are caused by these, so antibiotics fail
Viruses
Learn more: Antibiotics work on bacteria; taking them for a cold doesn't help and breeds resistant bacteria.
What a vaccine trains your body to do
Recognise a germ
Learn more: It shows the immune system a harmless piece or copy of a germ, so it reacts fast to the real one.
Protection for all when most people are immune
Herd immunity
Learn more: When enough people are immune, a germ can't spread, which protects those who can't be vaccinated.
How long to wash your hands with soap
At least 20 seconds
Learn more: Soap breaks up the fatty coat of many germs, but it needs time and rubbing to work.
Doctor who urged handwashing in 1847
Ignaz Semmelweis
Learn more: Deaths of new mothers fell sharply when doctors washed their hands, but colleagues mocked him.
Small glands in your neck that swell when you're ill
Lymph nodes
Learn more: They trap germs and gather immune cells, which is why they swell during an infection.
Immune reaction to something harmless, like pollen
An allergy
Learn more: The immune system mistakes a harmless substance for a threat and releases histamine.
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