The lymphatic system's role in fluid balance includes what action?

• A. It conserves fluid and plasma that leak out of capillaries.
• B. It releases hormones into the blood.
• C. It transports red blood cells.
• D. It filters air.

Answer: (A)

The lymphatic system preserves fluid balance by reclaiming the fluid that leaks out of capillaries. As capillaries exchange substances, plasma escapes into the surrounding tissue; most of it is reabsorbed into the blood, but some remains as interstitial fluid. Lymphatic capillaries pick up this excess fluid and proteins, forming lymph. This lymph travels through a network of vessels and nodes, then returns to the bloodstream—typically into the venous system near the left subclavian vein. By returning this fluid, the body maintains blood volume and tissue fluid balance, preventing edema.

Other listed functions aren’t roles of the lymphatic system: releasing hormones into the blood is an endocrine function, transporting red blood cells is a task of the circulatory system, and filtering air happens in the respiratory system.