LYMPH

                                                  Lymphatic System

The plasma and white cells that leak out of the blood capillaries must eventually be returned to the blood. In the tissues, as well as blood capillaries, are other small vessels. They are lymphatic capillaries. The tissue fluid slowly drains into them. The fluid s now called lymph.
         The lymphatic capillaries gradually join up to form larger lymphatic vessels. They carry the lymph to the subclavian veins which bring blood back from the arms. Here the lymph enters the blood again.
         The lymphatic system has no pump to make the lymph flow. Lymph vessels do have valves in them, however, to make sure that movement is only in one direction. Lymph flows much more slowly than blood. Many of the larger lymph vessels run within or very close to muscles, and when the muscles contract they squeeze inwards on the lymph and force it to move along the vessels.  

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