Return of Tissue Fluid to Blood

The loss of tissue fluid from the capillaries reduces the hydrostatic pressure inside them. When blood reaches the venous end its hydrostatic pressure is lower than the tissue fluid outside it. Therefore tissue fluid is forced back into the capillaries by the higher hydrostatic pressure outside them. Water enters the capillaries from the tissue via osmosis as it has a lower water potential than the tissue fluid.The remainder of the tissue fluid is carried back via the lymphatic system.The lymphatic system forms a network throughout the body. The contents of the lymphatic system are moved by the hydrostatic pressure of the tissue fluid that left the capillaries and the contraction of body muscles that squeeze the lymph vessels. Two ducts drain their contents back into the bloodstream (into the subclavian vein).