The quantity and role of water in the body.Signs and Symptoms of deficit or excess of water

In the average young adult male 18% of the body weight is protein and related substances,7% is minerals and 15% is fat.The remaining 60% is WATER!
The total amount of water in a man of average weight (for exemple 70 kg) is approximately 40 liters.
In a newborn infant,this total amount of water may be as high as 75% of body weight,but it progressively decreases from birth to old age and most of the decrease occurring in the first 10 years of life.

The intracellular component of body water accounts for about 40% of the body weight and the extracellular component for about 20%.Approximately 25% of the extracellular component is in the vascular system: for exemple plasma 55 of the body weight,75% outside the blood vessels and intestitial fluid 15% of the body weight.

Daily intake of water:
About 2/3 of our daily intake of water is in the form of pure water or other beverage,and the remainder is in the food that is eaten.
150 to 250 ml/day is synthesized in the body as a result of oxidation of hydrogen in the food.
The normal intake of fluid,including that synthesized is about 2300 ml/day.

Daily loss of body water:
The water is lost from the body under different conditions.Under normal condition the daily intake of water has to be equal with the daily loss of water.Changes occurs in case of diabetes (when there is a disproportion between the amount of electrolytes and the amount of water ingested or loss from the body).

Ingested water diffuses freely across almost all cell membranes from areas with high water concentration to areas with low water concentration.

Since two thirds of body water is intracellular and one third is extracellular,water is gained or loss from the body in the same proportion from both compartments.

For exemple if an individual drinks 3 liters of water,2 liters will diffuse in to the cells and 1 liter will remain in the extracellular fluids.water loss will be distributed in the same proportions.

Water deficit:
Water deficit is caused by:
-decreased water intake
-increased water loss
-increased solute ingestion or metabolic disorders as diabetes.

The symptoms of water deficit:
Vary according to the cause,severity of the change and the time course.
Symptoms include:
-restlessness
-increased irratability
-tremors
-tonic spasm
-can lead to death from respiratory failure.

Water excess:
Can occur as a result of :
-excess water intake
-decreased water excretion
-renal sodium loss.
Symptoms and signs of water excess:
-intense thirst
-anorexia
-muscle cramps
-weakness
-lethargy
-restlessness
-confusion
-delirium
-death.