ScienceVerseLearning path: Immune system
The concepts to learn before Immune system, in order. Each step links to its page and, where one exists, its quiz.
Sign in to see which steps you have already opened and which quizzes you have completed.
Your path
- CellDirect prerequisite
The basic structural and functional unit of all known living organisms. Every living thing is made of one or more cells, each bounded by a membrane and containing the machinery needed to grow, respond to its environment, and reproduce. Cells fall into two broad types: prokaryotic cells (such as bacteria), which lack a nucleus, and eukaryotic cells (such as those in plants, animals and fungi), which organise their DNA inside a membrane-bound nucleus.
- Immune systemYour goal
The immune system is the body's defence network: cells, tissues and proteins that recognise substances called antigens and respond to them. Innate immunity — barriers such as skin and mucus, plus fast-acting cells — is present from birth and acts within minutes to hours. Adaptive immunity, carried out by B and T lymphocytes, takes days to weeks to build up but targets specific antigens and keeps a memory, so a second encounter is met faster; vaccines use that memory without the illness itself.