What is the primary function of lymph nodes?

• A. They filter blood
• B. They remove pathogens and dead cells from lymph
• C. They store calcium
• D. They produce insulin

Answer: (C)

Lymph nodes act as filtering stations for lymph. As lymph flows through a node, immune cells such as macrophages and lymphocytes inspect the fluid for pathogens and debris. If something foreign is detected, it’s captured and destroyed, and antigens are presented to lymphocytes to kick off an adaptive immune response. This is why nodes play a crucial role in defending the body and why they often swell during infections. Other organs handle different tasks: filtering blood is mainly done by the spleen and liver, calcium is stored in bones, and insulin is produced by the pancreas.