It’s all about the lymph…

In response to Sophie’s question…


Tissue fluid (or interstitial fluid) is the fluid that surrounds our cells. It is basically water with dissolved solutes like sugars, salts, amino acids and waste products from the cells. Blood vessels have pores in them that allow the movement of molecules between the tissue fluid and the blood plasma (which is pretty much the same composition as the tissue fluid. You can think of the cells as balloons full of water sitting in a bath also full of water. Molecules are moving between tissue fluid and the cells (osmosis, diffusion for example) constantly; the presence of the cell membranes allow some molecules to build up in concentration and to separate the cell from its surroundings.

Lymph is tissue fluid that has entered the lymph channels (the system of vessels that lymph fluid moves through).  Lymph transports excess tissue fluid and proteins back to the blood. Lymph nodes are ‘blobs’ along the lymph channels filled with white blood cells that destroy pathogens. The lymph is moved along the channels by the incidental movement of skeletal muscle and some peristalsis.  Unfortunately, lymph channels also sometimes act as a quick route around the body for cancerous cells that have broken off from a tumour, which are carried around the body and may start growing in other tissues (metastasis).


Author: Mr Whellan's science

Nomadic science teacher

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