A significant fraction of the human body is water. This body water is distributed in different compartments in the body. Lean muscle tissue contains about 75% water. Blood contains 83% water, body fat contains 25% water and bone has 22% water. Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

In diseased states where body water is affected, the compartment or compartments that have changed can give clues to the nature of the problem.

Body water is regulated by hormones, including anti-diuretic hormone (ADH), aldosterone and atrial natriuretic peptide. Norepinephrine A hormone (from Greek όρμή - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Antidiuretic hormone (ADH), or arginine vasopressin (AVP), is a peptide hormone produced by the hypothalamus, and stored in the posterior part of the pituitary gland. ... Aldosterone is a steroid hormone (mineralocorticoid family) produced by the outer-section (zona glomerulosa) of the adrenal cortex in the adrenal gland to regulate sodium and potassium balance in the blood. ... Atrial natriuretic factor (ANF), atrial natriuretic peptide (ANP) or atriopeptin, is a polypeptide hormone involved in the homeostatic control of body water and sodium. ...

There are many methods that can be used to determine body water. One way to get a simple estimate is by calculation.

Calculation of body water

In individuals of normal weight, water is abundant in most parts of the body, except in adipose tissue (fat). These calculations are for adults of average build, and are inappropriate for obese or overly muscular people. These proportions are very simplified and use round numbers for quick calculation. It has been suggested that Subcutaneous fat be merged into this article or section. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... Obesity is a condition in which the natural energy reserve, stored in the fatty tissue of humans and other mammals, is increased to a point where it is associated with certain health conditions or increased mortality. ...

In men about 1% of the body mass is water. This value is about 200% in women due to a higher proportion of body fat. This is the total body water.

Body water is broken down into the following compartments:^[1]

• Intracellular fluid (2/3 of Body Water)
• Extracellular fluid (1/3 of Body Water)
  • Plasma (1/4 of Extracellular fluid)
  • Interstitial fluid (3/4 of Extracellular fluid)
  • Transcellular fluid (normally ignored in calculations)
    • Contained inside organs, such as the gastrointestinal, cerebrospinal, and ocular fluids.

The cytosol (as opposed to cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... In some animals, including mammals, the two types of extracellular fluids are interstitial fluid and blood plasma. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... Interstitial fluid (or tissue fluid, or intercellular fluid) is a solution which bathes and surrounds the cells of multicellular animals. ... Transcellular fluid is the portion of total body water contained within epithelial lined spaces. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space in the brain (the space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges). ... For other uses, see Eye (disambiguation). ...

Measurement of body water

Dilution and equilibration

Total body water can be determined using Flowing afterglow mass spectrometry FA-MS measurement of deuterium abundance in breath samples from individuals. A known dose of deuterated water (Heavy water, D2O) is ingested and allowed to equilibrate within the body water. The FA-MS instrument then measures the deuterium-to-hydrogen (D:H) ratio in the exhaled breath water vapour. The total body water is then accurately measured from the increase in breath deuterium content in relation to the volume of D2O ingested. Flowing afterglow mass spectrometry is a sensitive and quantitative mass spectrometry analytical approach that offers a route to on-line, real-time deuterium abundance measurements in water vapour in breath and above aqueous liquids, including urine and serum. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ...

Different substances can be used to measure different fluid compartments:^[2]

• total body water: tritiated water or deuterium
• extracellular fluid: inulin
• blood plasma: Evans blue

Tritiated water is a form of water where the usual hydrogen atoms are replaced with tritium. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... In some animals, including mammals, the two types of extracellular fluids are interstitial fluid and blood plasma. ... Note: This article title may be easily confused with insulin. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... For the dye, see Evans blue Evans Blue is a rock band from Toronto, Ontario, Canada founded in 2005. ...

Bioelectrical impedance analysis

Another method of determining total body water percentage (TBW%) is via Bioelectrical Impedance Analysis (BIA). In the traditional BIA method, a person lies on a cot and spot electrodes are placed on the hands and bare feet. Electrolyte gel is applied first, and then a current of 50 kHz is introduced. BIA has emerged as a promising technique because of its simplicity, low cost, high reproducibility and noninvasiveness. BIA prediction equations can be either generalized or population-specific, allowing this method to be potentially very accurate. Selecting the appropriate equation is important to determining the quality of the results.

For clinical purposes, scientists are developing a multi-frequency BIA method that may further improve the method's ability to predict a person's hydration level. New segmental BIA equipment that uses more electrodes may lead to more precise measurements of specific parts of the body.

Conditions associated with abnormal body water

• Renal failure
• Obesity
• Third Spacing

Renal failure is the condition in which the kidneys fail to function properly. ... In human physiology, extracellular fluids are distributed between the interstitial compartment (i. ...

See also

• Body fat percentage

Body fat percentage is an estimate of the fraction of the total body mass that is adipose tissue (or referred to as Fat Mass), as opposed to lean body mass (muscle, bone, organ tissue, blood, and everything else) or referred to as Fat Free Mass. ...

References

1. ^ John T. Hansen, Bruce M. Koeppen, (2002). Netter's Atlas of Human Physiology. Teterboro, N.J: Icon Learning Systems. ISBN 1-929007-01-9. 
2. ^ Physiology at MCG 7/7ch02/7ch02p13

In 1828 the Medical Academy of Georgia was chartered by the state of Georgia with plans to offer a single course of lectures leading to a bachelors degree. ...

External links

• MeSH Body+water
• MeSH Body+fluid+compartments