Lymph is a component of the extracellular fluid of the body and is largely derived from fluid and solute filtered from the blood circulation across the capillary wall. A mixture of hydrostatic forces and osmotic pressure control the fluid content of the blood. The high pressure within the arteriolar capillaries forces plasma into the intercellular spaces, the majority of which is returned to the bloodstream at the venous end of the capillary. The volume and solute concentration of the filtrate is modified by passage through the tissues and the lymphatic vessel endothelium before becoming lymph. About 10% of the fluid flowing from the arterial capillaries is absorbed by the lymphatic capillaries and returns to the bloodstream through the lymphatic system.
The sparse and incomplete basement membrane of the endothelium of small lymphatics is a weak barrier to the passage of solutes, fluids and large particles. In addition, the intercellular adhesion is poor and hence large particulates and even cells can occasionally pass between them. Specific vesicular transport may also be an important route of entry.
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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...