6. The lymphatic system
The final section of this learning module focuses on the lymphatic system. The lymphatic system can be considered as the ‘second’ circulatory system in the body.
Normally more fluid leaves the capillaries than is drawn back into the blood. Any excess fluid, together with any large molecules that have leaked through the capillary walls, is absorbed into the lymphatic system.
The lymphatic system involves :
- lymph vessels (a network of channels throughout the body)
- lymph nodes and other lymphatic tissue
- the spleen, and
- the thymus gland.
In addition to returning tissue fluids to the circulation, the lymphatic system has another important function – it helps defend the body against infection.