The lymphatic system

16 The lymphatic system



As blood passes through the capillaries in the tissues, fluid oozes out through the porous walls and circulates through the tissues, bathing every cell. This fluid is called tissue or interstitial fluid; it fills the interstices or the spaces between the cells that form the different tissues (Fig. 16.1). It is a clear, watery, straw-coloured fluid similar to the plasma of the blood from which it is derived. While blood circulates only through the blood vessels, tissue fluid circulates through the actual tissue and carries nutrients, oxygen and water from the blood stream to each individual cell and carries away its waste products such as carbon dioxide, urea and water, transmitting them to the blood. It is, in other words, the carrying medium between the tissue cells and the blood.



Of the fluid that escapes from the capillaries into the tissues, a certain amount passes back through the capillary wall but its return is more difficult than its escape owing to the constant stream of oncoming blood that fills the capillaries. The excess fluid that cannot return directly into the blood stream is collected and returned to the blood by a second set of vessels, which form the lymphatic system; the fluid that these vessels contain is called lymph. If fluid accumulates in the interstitial tissues and is not removed by the lymphatic system, oedema results.



The components of the lymphatic system


The lymphatic system comprises four types of structure:







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Jul 18, 2016 | Posted by in NURSING | Comments Off on The lymphatic system

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