Immune System
The immune system defends against pathogens.
About this topic
The immune system protects against pathogens. Non-specific defences include skin, mucus, stomach acid and phagocytes that engulf invaders. Specific immunity uses lymphocytes: B cells produce antibodies that target particular antigens, and T cells destroy infected cells and coordinate responses. Memory cells give faster, stronger responses on re-exposure.
Inflammation and fever help fight infection. Allergies are overreactions to harmless substances, and autoimmune diseases occur when the body attacks itself.
When bacteria enter a cut, phagocytes engulf them while inflammation brings more cells to the site. If the pathogen persists, lymphocytes recognise its antigens: B cells produce antibodies that lock onto them and mark them for destruction, and T cells kill infected cells. Memory cells remain afterwards, so a second infection is met with a faster and larger response.
Allergies are an overreaction to harmless substances such as pollen, and autoimmune diseases, like type 1 diabetes, happen when the body attacks itself. HIV attacks helper T cells, leading to AIDS. Fever and swelling are signs the immune system is working. A common misconception is that antibiotics boost immunity or kill viruses; they do neither. Rest and good nutrition really do support defence.
Key ideas
- White blood cells, antibodies
- Non-specific and specific defence
- Memory cells give lasting protection
Quick check
Use cases: where Immune System helps
- Homework: review the key idea behind Immune System before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Immune System without notes.
- Visual learning: play with the interactive lab to see how Immune System changes when you adjust its inputs.
- Teaching a friend: explain Immune System in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Immune System?
The immune system defends against pathogens.
What will I learn in Immune System?
White blood cells, antibodies. Non-specific and specific defence. Memory cells give lasting protection.
Is Immune System part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Immune System lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Immune System?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.