A lymph capillary is a capillary or tiny vessel found anywhere in the lymphatic system. Lymph is a fluid made of mostly of water, proteins, and dissolved substances which have been released from cells. Lymph is not contained within veins or arteries, but rather surrounds cells. The lymph capillaries are tiny, tube-like vessels that take the water up into the lymphatic system. This system is part of the larger circulatory system, and it also is part of the immune system.
The purpose of a lymph capillary is to take up the waste water excreted by cells and deposit it into the lymphatic system. This water will then be filtered or cleaned of toxins for return to the blood stream. Water has the unique property of adhering to surfaces, and when a tube or vessel is very tiny in diameter, as is the lymph capillary, this property will cause the water to draw up into the tube. This is called capillary action, and it is the means by which waste water from cells is taken up into the lymphatic system.
Upon entering a lymph capillary, the waste water released by cells is then moved into the larger vessels of the lymphatic system by contraction of muscles. This waste water is also the patrol ground for tiny, specialized cells called lymphocytes that will attack and engulf toxins and microorganisms such as bacteria. As lymph moves through the capillary, it passes through lymph nodes which collect toxins and worn out lymphocytes. Clean lymph can then continue on towards reentry into the blood stream.
The most familiar organs in the lymphatic system are the tonsils. Infections often result in lymph being thick with excess toxins and worn out lymphocytes, which can build up in the filters or lymph nodes such as the tonsils. When lymph nodes are engorged with lymphocytes, they are swollen and tender. This is the reason that doctors often look at the back of the throat or feel the lymph nodes in the neck area to assess illness.
The proper movement of lymph depends on muscle contractions throughout the body. This movement is quite different from the movement of blood through veins and arteries, as the blood is continuously pumped along by the heart. Adequate water is needed to keep lymph flowing easily, and muscles must be strong and fit in order to move the lymph along. Since the lymphatic system is vital in cleaning the blood and in fighting infection, it plays a key role in immunity in general. Drinking plenty of water and exercising daily can help this system to maintain optimum function.