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Read Innate Defence from Barrier to Signal
Innate immunity acts rapidly through barriers, cells and local chemical signals.
NSEB · Human Health and Disease · 2 linked questions · 100% coverage
Know this first
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Structure · The part being namedFunction · What that part doesCondition · The situation that changes the answer
Study deeper: NCERT Biology · Human Health and Disease
Sort the four barriers
Mucus and skin are physical barriers; stomach acid and tears are physiological; neutrophils and other phagocytes are cellular; interferons secreted by virus-infected cells are cytokine barriers.
Read the early inflammatory signal
Histamine released from mast cells can quickly dilate nearby arterioles, increasing local blood flow during inflammation. It is not secreted by plasma cells or lymphocytes in the keyed scenario.
OlympIQ exam lens
- ✓Physical: skin and mucus.
- ✓Physiological: acid and antimicrobial secretions.
- ✓Cellular: phagocytes and natural killer cells.
- ✓Cytokine: interferons; local vasodilation: mast-cell histamine.
OlympIQ trap
Match each example to the kind of barrier it is, not merely to the immune system in general.
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