Ónæmisviðbragða

Ónæmisviðbragða is the Icelandic term for immune response. It refers to the complex network of cells, tissues, and organs that work together to defend the body against harmful invaders, such as bacteria, viruses, parasites, and fungi. This defense system is crucial for maintaining health and preventing illness.

The immune response can be broadly divided into two main types: innate immunity and adaptive immunity. Innate immunity is the body's first line of defense. It is non-specific, meaning it attacks any foreign substance it encounters. This includes physical barriers like the skin and mucous membranes, as well as cellular components like phagocytes that engulf and destroy pathogens, and inflammatory responses that recruit immune cells to the site of infection.

Adaptive immunity, on the other hand, is highly specific and develops over time. It involves specialized cells called lymphocytes, specifically B cells and T cells. B cells produce antibodies, which are proteins that target specific pathogens. T cells have various roles, including helping B cells produce antibodies, directly killing infected cells, and regulating the immune response. A key feature of adaptive immunity is immunological memory, where the body "remembers" a pathogen after initial exposure, allowing for a faster and stronger response upon subsequent encounters. This is the principle behind vaccination.

When the immune system functions correctly, it protects the body from disease. However, sometimes the immune system can malfunction, leading to autoimmune diseases where it attacks the body's own tissues, or allergies where it overreacts to harmless substances.