Lymphatic System




What is Lymphatic System?

It is known to us that the blood is circulating in almost all parts of the human body. When circulating blood reaches the capillaries, part of its fluid content passes into the adjacent tissues as tissue fluid. Most of this fluid re-enters the capillaries at their venous ends. Some of it, however, returns to the circulation through a separate system of lymphatic vessel which is called lymphatic. The fluid passing through the lymphatic vessels is called lymph. The smallest lymphatic vessels are lymphatic capillaries which unite together to form larger lymph vessels. The lymph vessels from various parts of the body ultimately end in a few large vessels through which lymph drains into the blood stream by joining the sub-clavian veins at their connection with the internal jugular veins. The whole system is called the lymphatic system in human body.

Lymphatic System
Several very tiny, bean-shaped structures are scattered along the course of lymphatic vessels, and these structures are called lymph nodes. In general, they are thinly scattered, but in some parts of the body, mainly in the neck, groin, and arm pits, they gather together in large numbers. Within each node there is a series of fibrous traps through which lymph flows. As a rule, lymph from any part of the body passes through one or more lymph nodes before ingoing to the blood stream. However, there are some exceptions to this rule. As example, some lymph from the thyroid gland drains directly into the thoracic duct.




Aggregations of lymphoid tissue are also found at various other sites. Thymus is a large lymphoid organ located in the anterior of the thoracic cavity and lower part of the neck. Spleen is another large lymphoid situated in the left upper part of the organ situated in the left upper part abdomen. Important aggregations of lymphoid tissue are also present in close relationship to the lining epithelium of the gut. Such aggregations present in the region of the pharynx constitute tonsils. In lymphatic system, isolated nodules of lymphoid tissue, and larger aggregations, called Peyer's patches, are present in the mucosa and sub-mucosa of the small intestine. The mucosa of the vermiform appendix also contains abundant lymphoid tissue. Lymphoid tissues are also present in the walls of the trachea and larger bronchi.



What is Lymph?

The lymph is fluid that circulates in the human circulatory lymphatic system. It is derivative of blood plasma, but clearer and more watery, lymph seeps through the capillary walls to fill tissue spaces. It contains the same proteins as in blood plasma, but in smaller amounts and in somewhat different proportions. There are present various cells suspended in lymph that are mainly lymphocytes. Lymphocytes are added to lymph as it passes through lymph nodes in the lymphatic system.

What are the functions of Lymphatic System?

Lymphatic system is related to cardiovascular system. The lymphatic system performs a number of major functions. It is important in the body's resistance mechanism, filtering out disease causing organisms, manufacturing white blood cells, as well as generating antibodies. The lymphatic system is also important in the distribution of fluid and nutrients all over the body because it drains off excess fluids and proteins left behind by the capillary circulation so that the tissues do not swell. Moreover, spleen removes old and worn red cells from the blood, returning iron to the blood for reuse in synthesizing hemoglobin, and breaking down the remainder Spleen also stores extra blood for release when shortages take place.

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