Which system consists of 30 proteins produced by the liver that play a role in the immune response?

• A. Immune System
• B. Complement System
• C. Lymphatic System
• D. Coagulation System

Answer: (B)

The complement system is a crucial part of the immune response, composed of approximately 30 proteins produced primarily by the liver. These proteins work together in a cascade to enhance the ability of antibodies and phagocytic cells to clear pathogens from an organism. The complement system is involved in various immune functions, including opsonization (marking pathogens for destruction), chemotaxis (attracting immune cells to sites of infection), and the formation of membrane attack complexes that can directly lyse pathogens.

The proteins in the complement system can be activated through multiple pathways, including the classical pathway (triggered by antibodies), the alternative pathway (activated by pathogen surfaces), and the lectin pathway (activated by specific carbohydrate sequences on pathogens). This multi-faceted activation allows the complement system to respond to a wide array of microbial challenges, highlighting its integral role in the body's defense mechanism.

The other systems mentioned have distinct roles; for example, while the immune system encompasses a broad range of defenses, including cellular and humoral responses, it is not defined solely by the complement proteins. The lymphatic system is responsible for the transport of lymph and is key in immune function, but it does not consist of proteins like the complement system does. The coagulation system primarily focuses