Memory: One of the most crucial functions of the immune system is the ability to remember past encounters with specific pathogens. This memory allows the immune system to mount a faster and more effective response upon subsequent exposure to the same pathogen, providing immunity against future infections.
Innate Immunity: This type of immunity provides immediate, nonspecific protection against a wide range of pathogens. It serves as the body's first line of defense and includes physical barriers like the skin and mucous membranes, as well as cellular components such as macrophages, neutrophils, and natural killer cells. Innate immunity is present from birth and does not require prior exposure to pathogens.
Adaptive Immunity: Also known as acquired immunity, this type of immunity develops over time as a result of exposure to specific pathogens or vaccines. Adaptive immunity is highly specific and targeted, allowing the immune system to mount a tailored response against particular pathogens. It involves specialized immune cells called lymphocytes, including T cells and B cells. T cells are responsible for cell-mediated immunity, which involves directly attacking infected or abnormal cells. B cells produce antibodies, which bind to and neutralize pathogens or mark them for destruction by other immune cells. Adaptive immunity also includes immunological memory, providing long-lasting protection against recurrent infections.