The excretory system

The excretory system is the term sometimes employed to describe collectively the organs that deal with the excretion of waste products from the body. These organs include the urinary system, the lungs in their function of eliminating carbon dioxide, and the colon which excretes certain insoluble substances in the faeces.

The body fluids

Water with its solvents needed for the health of the cells is termed body fluid, and this fluid is partly inside and partly outside the cells.

Intracellular fluid from 50 percent of the body weight; it lies within the cells, and contains electrolytes including potassium and phosphates and food materials like glucose and amino-acids. Enzyme action is constant within the cells, breaking down and building up as in all metabolisms to maintain a balance.

  Extracellular or interstitial fluid represent 30 percent of the water in the body. It is the medium in which the cells live, obtaining from its salt, food, and oxygen and passing into it their waste products.

   Blood plasma from 5 percent of body weight and it is the transport system which serves the cells through the medium of the extracellular fluid.