Lymph System - Cleaning Up the FluidsWe have already discussed the circulatory system that has your blood and transports nutrients, dissolved gases, and waste products through your body. There is a closely related system called the lymphatic system. While the circulatory system circulates blood throughout your body, the lymph system moves lymph fluid through the body. Not all organisms have lymph systems. This system is one of the more advanced systems you will find in animals.
What Does the System Do?The lymph system is designed for transportation in a way similar to the circulatory system, but it I not about oxygen and nutrients. The lymph fluid acts like the clean-up crew for your body. You know that you are made of water and fluids. There are very few solid parts of your body. All of those fluids are usually contained in cells. There are some fluids found between the cells or actually seep out of the cells. This intercellular fluid slowly begins to accumulate and must be returned to the cells and the blood stream. Enter the lymph system. The lymph system gathers those fluids and returns them to your blood. The lymph system is also closely associated with your immune system and swelling of tissues after an injury.
Interacting with Other SystemsWe keep talking about the collection of fluids. The lymph system is not a closed system in the way your circulatory system is closed. The lymph system collects and transports. Collection of fluids begins at the capillaries of the circulatory system and then the fluid directed through a series of vessels that become the thoracic duct. That duct is connected to the largest vein in your body, the superior vena cava, and returns the fluid to your heart and circulatory system.
The lymph fluid moves through the vessels as you move the voluntary muscles in your body. Ever go on a plane and have your feet swell up? Because you are sitting in one place and not moving around, fluid collects in your feet and they swell. The more you move, the more effective your lymphatic system becomes.
Important NodesWhen you get older, you may get sick and your doctor will check for swollen lymph nodes. Those nodes are often found in your thighs, armpits, and neck and are essential parts of your immune system. The nodes are actually accumulations of lymph tissue that serve a few purposes. They are great filters of foreign materials that can hurt your body. Bacteria and cancer cells often enter the lymph system and intercellular fluids are collected. Those tiny cells can be removed by the lymph cells and digested (on a cellular level). Not only do your nodes remove cells, they also create cells called lymphocytes. Those lymphocytes are white blood cells used by the immune system to produce antibodies or hunt down pathogens and eat them (using phagocytosis).
Ultrasound Imaging System (NASA/MSFC Video)