What system drains excess interstitial fluid from tissue spaces?

The lymphatic system is primarily responsible for draining excess interstitial fluid from tissue spaces. This system consists of a network of lymphatic vessels and lymph nodes that collect and transport lymph, a fluid containing white blood cells and other substances, back into the bloodstream. The drainage of interstitial fluid is crucial for maintaining fluid balance within the body, preventing edema (swelling), and ensuring proper immune function by facilitating the movement of immune cells.

This fluid is derived from blood plasma that seeps through capillary walls into the surrounding tissues; without the lymphatic system, this excess fluid could accumulate in the tissues, leading to complications. Additionally, the lymphatic system plays a vital role in filtering out pathogens via the lymph nodes, thus contributing to the body's overall defense mechanism.

Other systems mentioned, like the circulatory, respiratory, and endocrine systems, have different primary functions, such as transporting blood and nutrients, facilitating gas exchange, and regulating body processes through hormones, respectively. Therefore, while each system plays a vital role in maintaining homeostasis, the lymphatic system is specifically dedicated to the drainage of excess interstitial fluid.