The lymphatic system is very complex and it is made up lymphoid organs, lymph nodes, lymph ducts, lymph capillaries, and lymph vessels that make and transport lymph fluid from tissues to the circulatory system. The network of lymphatic vessels carry lymph a clear, watery fluid that contains protein molecules, salts, glucose, urea, and other substances throughout the body.
The lymphatic system is not a close system and the movement of the lymph fluid moves with low pressure due to functions such as peristalsis, valves, and the milking action of skeletal muscles. Lymph fluid only ever travels in one direction. Lymph fluid drains into lymph capillaries, which are tiny vessels. The fluid is then pushed along when a person breathes or the muscles contract. The lymph capillaries are very thin, and they have many tiny openings that allow gases, water, and nutrients to pass through to the surrounding cells, nourishing them and taking away waste products. When lymph fluid leaks through in this way it is called interstitial fluid. Lymph vessels collect the interstitial fluid and then return it to the bloodstream by emptying it into large veins in the upper chest, near the neck.
As the lymph fluid moves through the body, it collects waste products and toxins and disposes of them through the bladder, bowel, lungs, and skin. The lymphatic system is vital for both detoxification and the immune system, and if it is not working properly, then a wide range of illnesses can develop.
The lymphatic system helps defend the body against germs like viruses, bacteria, and fungi that can cause illnesses. Those germs are filtered out in the lymph nodes (small masses of tissue located along the network of lymph vessels). These nodes contain lymphocytes, a type of white blood cell. Some of those lymphocytes make antibodies (special proteins that fight off germs and stop infections from spreading by trapping disease-causing germs and destroying them). Hence the lymphatic system is considered to be a part of the immune system.