The body contains several hundred lymph nodes, mostly found in the upper torso. The main areas of nodes include the armpits, between the ribs, between the lungs, and on a small section of the lungs.
The lymphatic system works with the immune system to keep infection out of the body. In addition to nodes, the system also contains vein-like lymphatic ducts, which carry the lymph fluid back to the blood supply, capillaries and lymphatic nodules. There are four different nodules: tonsils, which actually are five types; Peyer's patches in the small intestine; the spleen; and the thymus.
The five tonsils are made up of two lingual, two palatine and one pharyngeal, all located in the head and neck area. When infection is present, the tonsils become inflamed.
The lymphatic system moves fluid from body tissues into the circulatory system. It also transports fatty acids from the digestive system, and the acids turn the lymph fluid into milky white chyle, which gets metabolized by the liver.
Lymph fluid is also known as interstitial fluid, which is plasma that has leaked from tissues. This fluid picks up waste, pathogens and tumor cells if present. Anything solid in the liquid gets trapped in the nodes, stopping them from spreading through the body.