The immune system can be broadly divided into two components: the innate immune system and the adaptive immune system. The innate immune system provides immediate, non-specific defense against pathogens. It includes physical barriers like the skin, mucous membranes, and various cells such as macrophages and neutrophils. The adaptive immune system, on the other hand, is highly specific and involves lymphocytes such as B cells and T cells. This system has a memory component, allowing for a quicker and stronger response upon subsequent exposures to the same pathogen.
