[Free Registration/Login may be required to access all resource tools.] Almost all of us have had a sore throat at some time. Maybe you had your tonsils out when you were younger? Why? Your tonsils are two lumps of tissue that work as...

[Free Registration/Login may be required to access all resource tools.] The lymphatic system is a network of vessels and tissues that carry a clear fluid called lymph. The lymphatic system works with the cardiovascular system to return...

Find out how the body rids itself of wastes and fights off infections with the help of the lymph nodes and white blood cells.

Take this interactive, multiple-choice quiz over the human immune system, then review your score and any missed questions at the end.