Final answer:
Hypersensitivity involves excessive immune responses to typically harmless substances, with type I being immediate (e.g., allergies) and delayed hypersensitivity taking longer to manifest (e.g., contact dermatitis). Autoimmunity is a self-targeting immune response, where the immune system attacks the body's cells, seen in diseases like type I diabetes mellitus, multiple sclerosis, and rheumatoid arthritis. Pemphigus foliaceus is a specific autoimmune condition that causes blistering of the skin.
Step-by-step explanation:
Hypersensitivity refers to the exaggerated response of the immune system to an antigen that is typically seen as harmless. In type I hypersensitivity, previous sensitization to an allergen leads to an allergic reaction upon re-exposure, involving a rapid IgE-mediated immune response. Allergies, such as hay fever and asthma, fall under this category. Delayed hypersensitivity, on the other hand, includes responses like contact dermatitis or the tuberculin reaction, which take one to two days to manifest fully.
Autoimmunity is when the immune system erroneously targets the body's tissues, with diseases like type I diabetes mellitus, multiple sclerosis, and rheumatoid arthritis being well-known examples. Pemphigus, although not mentioned in the student's provided information, is another autoimmune disease where the immune system attacks the skin or mucous membranes. It's worth noting, however, that pemphigus foliaceus specifically is a rare autoimmune disease characterized by superficial blistering of the skin.
Contact dermatitis is a common occurrence and represents a mild form of hypersensitivity, while systemic diseases like systemic lupus erythematosus illustrate the complexity and severity that autoimmune diseases can exhibit. Treatments often involve immunosuppressive and anti-inflammatory drugs, aiming to alleviate symptoms rather than cure the underlying immune dysfunction.