Fluids
Composition of body fluid in healthy adults comprises of 60% water of the body weight that exists in compartments. Intracellular compartments (present within cells) is called as the ICF contains of 2/3rds of the body water or 40% of body weight. The extra cellular (present outside cells) or ECF contains 1/3rds of the total body. Blood constitutes 1/3rd of the ECF volume.

The main electrolytes in the human body
The human body mainly consists of the following electrolytes:
Sodium, potassium, chloride, bicarbonate phosphate, and sulphates.

Potassium is the principal component of intracellular fluid and 98% of the body potassium is intracellular. The principal anions of the intracellular fluid vary and they usually include phosphates, sulphates and negatively charged micro–molecules.

Volume depletion in the body and treatment
Loss of fluid or blood from the body is called volume depletion. Seen in loss of blood due to hemorrhage, loss of fluid from vomiting, diarrhea, or loss of excess water from the urine as with diuretics.

The clinical manifestation depends on the degree and rapidity of the fluid that is lost. If it is mild, the patients just exhibits some giddiness, weakness, increased thirst, dryness of mouth. If it is more advanced, it can result in decreased blood pressure and urine output.

The treatment of volume contraction is by replacing the appropriate fluid. Blood is used when there is hemorrhage. Albumin and plasma infusions can be used in emergency situations.

Solutions containing sodium (normal saline, ringer lactate) are used in situations such as vomiting and diarrhea.