The immune system is your body's defence network against pathogens — bacteria, viruses, fungi, and parasites. It operates on two levels: innate immunity (fast, non-specific) and adaptive immunity (slower, highly specific).
The innate system responds immediately to anything recognised as foreign. Skin is the first barrier. If pathogens breach it, immune cells like neutrophils and macrophages attack using inflammation — redness, swelling, and heat are signs of this response working.
The adaptive system is slower but devastatingly precise. When the innate system flags a threat, specialised white blood cells called T cells and B cells are activated. B cells produce antibodies — proteins specifically shaped to bind to that particular pathogen and neutralise it. T cells directly destroy infected cells.
Memory cells remain after infection resolves, enabling faster response to the same pathogen years later. This is how vaccines work — they trigger this memory formation without causing the disease itself.
Autoimmune diseases occur when the immune system mistakenly attacks the body's own tissues — conditions like rheumatoid arthritis, lupus, and type 1 diabetes.
by jamespatel76007
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