What is the definition or description of: lymph nodes?

Lymph nodes: I like to think of lymph nodes as beads on the string of the lymphatic channels. The lymphatic system is the low pressure system that looks a lot like your blood vessels but without the heart. Your body is able to get that little extra fluid that accumulates in, say your ankles, back to your heart by the lymph channels.The nodes act like filters to catch bacteria and cancer cells, trapping them.

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells and digested food. Lymph nodes "taste" the lymph for anything bad like bacteria, viruses, cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.