Medicine & Health
What is The immune system?
The immune system is the body's defense network — a coordinated set of cells, tissues, and organs that detects and destroys harmful invaders like bacteria and viruses, and learns to recognize threats it has met before.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains the immune system.
Key things to understand
- 1Innate immunity is the fast, general first line (skin, inflammation, cells that attack anything foreign).
- 2Adaptive immunity is slower but specific: it makes antibodies tailored to one pathogen and remembers it.
- 3White blood cells such as T cells and B cells coordinate the response.
- 4'Memory' cells let the body respond much faster next time — the basis of how vaccines work.
Frequently asked questions
- What are antibodies?
- Proteins the immune system makes that lock onto a specific pathogen to neutralize it or tag it for destruction.
- What's the difference between innate and adaptive immunity?
- Innate is the fast, general defense you're born with; adaptive is the slower, specific defense that learns and remembers particular threats.
- How does the immune system remember diseases?
- After fighting a pathogen it keeps memory cells that recognize it, enabling a much faster response if it returns.