This system consists of a network of vessels, ducts, nodes, and organs and provides defense against infection. Which system is it?

This system consists of a network of vessels, ducts, nodes, and organs and provides defense against infection. Which system is it?

• A. Circulatory system
• B. Endocrine system
• C. Lymphatic system
• D. Digestive system

Answer: (C)

Defense against infection relies on a network that carries lymph through vessels and ducts, with nodes and immune organs scattered throughout the body. This system collects excess fluid from tissues, filters it through lymph nodes where immune cells detect and respond to pathogens, and uses organs like the spleen and thymus to train and deploy lymphocytes. The network of vessels and lymph nodes—together with these immune organs—defines the lymphatic system and its main job: to defend the body against infection and help keep tissue fluid balanced. While other systems have related roles (the circulatory system moves blood, the digestive system breaks down food, the endocrine system uses hormones), they don’t feature the prominent lymph nodes and lymphatic vessels that are essential to immune defense, which is why this choice fits best.

Defense against infection relies on a network that carries lymph through vessels and ducts, with nodes and immune organs scattered throughout the body. This system collects excess fluid from tissues, filters it through lymph nodes where immune cells detect and respond to pathogens, and uses organs like the spleen and thymus to train and deploy lymphocytes. The network of vessels and lymph nodes—together with these immune organs—defines the lymphatic system and its main job: to defend the body against infection and help keep tissue fluid balanced. While other systems have related roles (the circulatory system moves blood, the digestive system breaks down food, the endocrine system uses hormones), they don’t feature the prominent lymph nodes and lymphatic vessels that are essential to immune defense, which is why this choice fits best.