What is
The Lymphatic System?

The lymphatic system consists of organs, ducts, and nodes. It transports a watery clear fluid known as lymph. It interacts with the blood circulatory system to drain fluid from cells and tissues. The lymphatic system contains immune cells called lymphocytes, which protect the body against antigens (viruses, bacteria, etc.) that invade the body.

What are
Lymphocytes?

Lymphocytes are the second most common white blood cell type, comprising about 30 % of the leukocyte population in peripheral blood.
Lymphocytes travel in the blood, but they routinely leave capillaries and wander through connective tissue. Therefore, lymphocytes may be normally encountered at any time in any location. They even enter epithelial tissue, crawling between the epithelial cells. They re-enter circulation via lymphatic system channels.

What are the
Main Functions Of The System?

Lymph organs include the bone marrow, lymph nodes, spleen, and thymus. Besides providing a home for lymphocytes, the ducts of the lymphatic system provide transportation for proteins, fats, and other substances in a medium called lymph. Human lymph nodes are bean-shaped and range in size from a few millimetres to about 1-2 cm in their normal state. They may become enlarged due to a tumour or infection. White blood cells are located within honeycomb structures of the lymph nodes. In some cases they may feel enlarged due to past infections; although one may be healthy, one may still feel them residually enlarged.
These lymph capillaries are very permeable, and because they are not pressurized the lymph fluid can drain easily from the tissue into the lymph capillaries. As with the blood network the lymph vessels form a network throughout the body, unlike the blood the lymph system is a one-way street draining lymph from the tissue and returning it to the blood. Lymph nodes are filters of lymph, and the spleen is a filter of blood.