Adaptive defenses, also known as adaptive immunity, are a type of immunity that develops when your immune system responds to a specific foreign substance or microorganism. This response can occur after an infection or vaccination.
Here's a breakdown of adaptive immunity:
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Specificity: Adaptive immunity is highly specific. It targets particular pathogens or foreign substances, unlike innate immunity, which provides a more general defense.
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Memory: A key feature of adaptive immunity is its ability to "remember" previous encounters with pathogens. This immunological memory allows for a faster and more effective response upon subsequent exposure to the same pathogen. This is the basis of how vaccines work.
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Two Main Branches: Adaptive immunity has two main branches:
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Humoral Immunity: This branch involves B lymphocytes (B cells) and the production of antibodies. Antibodies are proteins that bind to specific antigens (foreign substances) and neutralize them or mark them for destruction by other immune cells.
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Cell-Mediated Immunity: This branch involves T lymphocytes (T cells), which directly attack infected cells or activate other immune cells to fight infection. There are different types of T cells, including:
- Helper T cells: Help activate B cells and cytotoxic T cells.
- Cytotoxic T cells: Directly kill infected cells.
- Regulatory T cells: Help suppress the immune response to prevent autoimmunity.
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Development: Adaptive immunity is not present at birth. It develops over time as you are exposed to different pathogens or receive vaccinations.
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Examples:
- Developing immunity to measles after having the disease or receiving the MMR vaccine.
- Producing antibodies against a specific strain of influenza after being infected.
In summary, adaptive defenses provide a highly specific and long-lasting form of immunity by "learning" and remembering encounters with pathogens, enabling the body to mount a faster and more effective response upon future exposure.
