Adaptive immunity
The part of the immune system that learns. B cells make antibodies that bind specific antigens. T cells kill infected cells or help other cells. Memory cells remain after infection, so a second infection is met quickly.
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Analogy
A security team with a photo album of every past intruder.
In practice
Vaccines show the immune system a harmless piece of a germ so memory cells form without the disease.
Practice
Flashcards
- How do memory cells help?They allow a fast and strong response on a second infection with the same germ.
Interview questions
- Compare innate and adaptive immunity and explain how vaccines work.
- Innate is fast and general, no memory
- Adaptive is specific, makes memory cells
- Vaccine presents antigen safely
- Second exposure gives faster response
Questions people ask
What are antibodies?
Antibodies are Y-shaped proteins made by B cells. Each type fits a specific antigen, a molecule on a germ. They bind the germ and mark it for destruction, block it from entering cells, or make germs clump together. The body can make millions of different antibodies.
How does HIV damage the immune system?
HIV infects and destroys helper T cells, which coordinate the immune response. As their numbers fall, the body struggles to fight infections and some cancers. This late stage is called AIDS. Modern drugs can keep the virus at very low levels, allowing people to stay healthy.