Alila Academy

In a nutshell, the lymphatic system is a drainage system that removes excess fluid from body tissues and returns it to the bloodstream. It is actually a subsystem of both the circulatory and immune system.

Circulatory function:

The major purpose of the circulatory system is to bring oxygen and nutrients to body tissues and remove wastes. This exchange happens in the smallest blood vessels called the capillaries. Blood plasma containing nutrients moves out of capillaries at the arterial end of capillary beds, while tissue fluid containing wastes reabsorbs back in at the venous end.

However, not all of the fluid is drawn back to the bloodstream at this point. About 15% of it is left in the tissues and would cause swelling if accumulated. This is where the lymphatic system comes into play, it picks up the excess fluid and returns it to the circulatory system.

Unlike the blood circulatory system, which is a closed loop, the lymphatic system is a one-direction, open-ended network of vessels. 

Lymphatic vessels begin as lymphatic capillaries made of overlapping endothelial cells. The overlapping flaps function as a one-way valve. 

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