# 77 Functions of lymphatic system

Credit: Adam

The lymphatic system is a collection of lymph vessels and glands. It has 3 main roles:

• Fluid balance: return tissue fluid to the blood

• Protection from infection: produce white blood cells lymphocytes

• Absorption of fats: transport digested fats from villi to blood stream

1. Lymph and Tissue Fluid

Tissue fluid is a fluid surrounding the cells of a tissue. It is leaked plasma - Plasma from the blood capillaries move to the tissue through gaps in the walls and become tissue fluid.

Tissue fluid play an important role in substance exchange between blood and cells. It supplies cells with O₂ and nutrients and takes away waste products including CO₂.

At the end of the capillary bed, the tissue fluid leaks back into the blood, and becomes plasma again, but not all of it. A little of it is absorbed by the lymphatic vessel and becomes lymph. 

The lymphatic vessel takes the lymph to the blood stream by secreting them in a vein near the heart, called subclavian vein. The lymph in the lymphatic vessels are moved along by the squeeze of muscles against the vessel, just like some veins.  

The return of tissue fluid to the blood in the form of lymph fluid prevents fluid built up in the tissue. 

 Credit: lubopitko-bg.com 

2. Production of lymphocytes

The lymphatic system is an important component of the immune system, which fights infection. One group of white blood cells, the lymphocytes, are made in lymph glands such as the tonsils, adenoids and spleen. The glands become more active during an infection because they are producing and releasing large numbers of lymphocytes. 

The lymphocytes can live and multiply in the lymphatic system, where they attack and destroy foreign organisms. Lymphoid tissue scattered throughout the body filters out pathogens, other foreign matter and cellular debris in body fluids. 

3. The absorption of fatty acids and glycerol from the small intestine  

Following the chemical and mechanical breakdown of food in the digestive tract, most nutrients are absorbed into the blood through intestinal capillaries. Many digested fats, however, are too large to enter the blood capillaries and are instead absorbed into lymphatic capillaries by intestinal lacteals. Fats are added to the blood when lymph joins the bloodstream.

Each villus contains a lacteal - a blind ending lymph vessel. 

Additional source:  lubopitko-bg

                                   Xtremepapers

Related topic: Absorbtion – function of the small intestine and significance of villi