Extracellular fluid

Extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese have a lower percentage than lean men. About two thirds of this is intracellular fluid within cells, and one third is the extracellular fluid. The main component of the extracellular fluid is the interstitial fluid that surrounds cells.Body water: Intracellular fluid/Cytosol Extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese have a lower percentage than lean men. About two thirds of this is intracellular fluid within cells, and one third is the extracellular fluid. The main component of the extracellular fluid is the interstitial fluid that surrounds cells. Extracellular fluid is the internal environment of all multicellular animals, and in those animals with a blood circulatory system a proportion of this fluid is blood plasma. Plasma and interstitial fluid are the two components that make up at least 97% of the ECF. Lymph makes up a small percentage of the interstitial fluid. The remaining small portion of the ECF includes the transcellular fluid (about 2.5%). The ECF can also be seen as having two components – plasma and lymph as a delivery system, and interstitial fluid for water and solute exchange with the cells. The extracellular fluid, in particular the interstitial fluid, constitutes the body's internal environment that bathes all of the cells in the body. The ECF composition is therefore crucial for their normal functions, and is maintained by a number of homeostatic mechanisms involving negative feedback. Homeostasis regulates, among others, the pH, sodium, potassium, and calcium concentrations in the ECF. The volume of body fluid, blood glucose, oxygen, and carbon dioxide levels are also tightly homeostatically maintained. The volume of extracellular fluid in a young adult male of 70 kg (154 lbs) is 20% of body weight – about fourteen litres. Eleven litres is interstitial fluid and the remaining three litres is plasma. The main component of the extracellular fluid is the interstitial fluid which surrounds the cells in the body. The other major component of the ECF is the intravascular fluid of the circulatory system called blood plasma. The remaining small percentage of ECF includes the transcellular fluid. These constituents are often called fluid compartments. The volume of extracellular fluid in a young adult male of 70 kg, is 20% of body weight – about fourteen litres. The interstitial fluid is essentially comparable to plasma. The interstitial fluid and plasma make up about 97% of the ECF, and a small percentage of this is lymph. Interstitial fluid is the body fluid between blood vessels and cells., containing nutrients from capillary by diffusion and holding waste products discharged out by cells due to metabolism. Eleven litres of the ECF is interstitial fluid and the remaining three litres is plasma. Plasma and interstitial fluid are very similar because water, ions, and small solutes are continuously exchanged between them across the walls of capillaries, through pores and capillary clefts. Interstitial fluid consists of a water solvent containing sugars, salts, fatty acids, amino acids, coenzymes, hormones, neurotransmitters, white blood cells and cell waste-products. This solution accounts for 26% of the water in the human body. The composition of interstitial fluid depends upon the exchanges between the cells in the biological tissue and the blood. This means that tissue fluid has a different composition in different tissues and in different areas of the body.