Answer
Interstitial fluid surrounds all body cells and is sometimes called the internal environment( "millieu interieur") of cells. The constancy of this environment is important for the cells to maintain balance of the controlled conditions under which they can function optimally. This relates to pH, electrolytes (Na, K concentrations etc), glucose, oxygen and carbon dioxide, levels of which constantly change between the cytosol and the fluid outside of and between cells. The movement of dilute solutions is bi-directional --from interstitial fluid through capillary walls into blood plasma and from blood plasma through thin capillary walls into interstitial fluid. By this exchange of nutrients, needed ions and oxygen are delivered to cells which in turn get rid of waste--carbon dioxide, ammonia. The cells receive substances for maintenance of normal pH and for energy production
Work Step by Step
The interstitial fluid between tissue cells is the fluid intermediary environment through which the cytosol of cells exchanges ions, nutrients, carbon dioxide, and oxygen with the blood plasma of the capillaries of the circulatory system. It is called the internal environment of the body because the pH levels of ions, oxygen, etc must be kept within certain ranges for the normal functioning of cells and the health of the organism.
