The Function and Structure of the Skin

The document detailed the structure and function of the skin, emphasizing its role as a protective barrier and its involvement in immunological reactions. It described the three layers of the skin—epidermis, dermis, and subcutis—and their specific functions, including protection, temperature regulation, sensation, and vitamin D synthesis. The epidermis contained keratinocytes, melanocytes, Langerhans cells, and Merkel cells, each contributing to pigmentation, immune response, and sensory transduction. The dermis provided structural support with fibroblasts, collagen, and elastic fibers, while the subcutis contained fat. The skin's immune system included various cells and molecules, such as MHC Class II molecules, antibodies, cytokines, and adhesion molecules, which played roles in immune responses and inflammation. The document also discussed different types of immune reactions, including Type III and Type IV reactions, and the formation of granulomas in response to persistent antigens.