the lymphatic system

The lymphatic system helps maintain fluid balance, defend the body against disease, ad absorb liquids from the intestine and transport them to the blood. It also collects and returns fluid that leaks from blood vessels, along with absorbing fats and vitamins, and protects our body against disease and microorganisms. 

Above is a diagram of a lymph node, which act as filters or traps for foreign substances and help us regulate our circulatory system. 

Lymph capillaries and veins help lymph flow through our bodies. Lymph is the fluid that flows through the lymphatic system. Lymph contains white blood cells and blood plasma, but its concentration is always changing, for when it leaves a lymph node, it is richer in lymphocytes, and it is richer in triglycerides when it leaves the digestive system. 

photo sources

http://www.dartmouth.edu/~nlevy/nodefigcorr4.jpeg
http://www.daviddarling.info/images/lymph_capillary.jpg