Lesson · S.1.11
The immune system
How the body's three lines of defense stop pathogens, and how the adaptive immune system learns to recognise them.
ObjectiveS.1.11Read2 minExam weightHuman Anatomy and Physiology ≈ 41% of Science
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- Place a given immune response, such as a fever or an antibody, in the correct line of defense.
- Explain how helper T cells activate cytotoxic T cells and B cells to fight a specific pathogen.
- Distinguish autoimmune disease, allergy, and HIV by what each disrupts in the immune response.
What the lesson concludes
- The three lines run from nonspecific to specific: barriers, then the innate cellular response, then the adaptive response.
- Inflammation, meaning histamines and phagocytes, is part of the innate response, not the adaptive one.
- B cells produce antibodies, T cells act directly on infected cells, a distinction the TEAS likes to test.
- Memory cells are why a second exposure to the same pathogen produces a faster response, and why vaccines work.
- Autoimmune disease attacks the body's own cells, allergy overreacts to a harmless substance, and HIV disables helper T cells specifically.