What does the lymphatic system consist of?

When the plasma moves out of the capillaries and into the spaces between tissue cells, it gets another name and is called interstitial fluid. Most, but not all, of this fluid gets reabsorbed into the capillary by differences in osmotic pressure. However, some does not, and this interstitial fluid must be drained from the tissue spaces to prevent swelling or edema from occurring. It is the role of the lymphatic capillaries to drain this fluid. Once the interstitial fluid enters a lymphatic capillary, it is called lymph .

The lymphatic system :

Lymphatic vessels originate as blind-end tubes that begin in spaces between cells in most parts of the body. The tubes, which are closed at one end, occur singly or in extensive plexuses and are called lymphatic capillaries. Lymphatic capillaries will eventually unite to form larger and larger lymph vessels called lymphatics. Eventually, all the lymphatics of the body converge into one of two main channels: either the thoracic duct or the right lymphatic duct.

Lymph nodes are oval to bean-shaped structures found along the length of lymphatics. They are also known as lymph glands.

The lymphatic system has some organs: the tonsils, spleen, thymus gland, and Peyer’s patches. Tonsils are masses of lymphoid tissue embedded in mucous membrane. There are three groups of tonsils. The palatine tonsils, the pharyngeal tonsils (adenoids) and the lingual tonsils.

The spleen is oval in shape and is the single largest mass of lymphatic tissue in the body. The thymus gland is a bi-lobed mass of tissue located in the mediastinum along the trachea behind the sternum.The thymus helps develop T lymphocytes in the fetus
and in infants for a few months after birth.

Peyer’s patches are found in the wall of the small intestine. They resemble tonsils. The vermiform appendix is another lymphatic organ; after birth, lymphoid tissue begins to develop in the appendix, reaching peak amounts around the age of 25. The appendix assists in the maturing of B lymphocytes.