Total Water Balance - Physiology
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Introduction
It is best that the fluid surrounding the cells remains fairly constant. If volume is varied dramatically then it has major knock on effects on the blood pressure and perfusion of the organs and tissue.
Animal Differences
There are differences in water content between the many tissue which make up the body. Tissue which have low metabolic activity such as adipose tissue and bone have relatively lower water content. This leads to a variation in water between individuals for example a very fat cow may only have a 40% body water content compared to 70% in a lean cow. There is also an age difference. Young animals tend to have a high body water content where as older well nourished animal have a lower.
Due to the differences in relative tissue distribution there is a sex related difference also. Males which tend to have more muscle have a higher water content where as female which tend to have more adipose tissue have a lower.
Water Locations
Although 65% of water is found intracellulary there is a significant quantity in the digestive and urinary tracts. In ruminants this could equal the volume of the interstial fluid. This water is not easy to mobilise but can be if required to stabilise blood volume.