What is lymph?

Lymph is a clear, slightly yellow fluid that is filtered by lymph nodes. It plays a critical role in the body's immune system by transporting white blood cells, particularly lymphocytes, throughout the body. These cells are essential for the body's defense mechanisms against infection and disease. The lymphatic system, which includes lymphatic vessels and lymph nodes, is responsible for returning excess interstitial fluid to the bloodstream and for aiding the absorption of fats and fat-soluble nutrients from the digestive system.

The other choices do not accurately describe lymph. While blood contains various components, including yellowish plasma, it is not accurate to define lymph as a fluid within blood. Lymph is distinct from blood cells; it is not a type of blood cell itself. Lastly, lymph is not a hormone; hormones are signaling molecules produced by glands in the body, and lymph serves a different function within the circulatory and immune systems. Understanding lymph and its role in immune function is essential for comprehending how the body protects itself against diseases.