Total Body Water and Body Fluid Compartments

Vocabulary flashcards covering body fluid compartments, total body water distribution, fluid compositions, and water balance.

Total Body Water (TBW)

The total volume of fluid contained in the human body, constituting approximately $60\%$ of total body weight in a standard $70\,\text{kg}$ adult male.

Intracellular Fluid (ICF)

The body fluid contained inside cells (cytosol), accounting for $2/3$ of total body water ($40\%$ of total body weight or about $28\,\text{L}$ in a $70\,\text{kg}$ adult).

Extracellular Fluid (ECF)

All body fluids located outside of cells, accounting for $1/3$ of total body water ($20\%$ of total body weight or about $14\,\text{L}$ in a $70\,\text{kg}$ adult).

Interstitial Fluid (ISF)

The sub-compartment of extracellular fluid that fills the spaces between tissue cells, comprising $3/4$ of the total ECF (approximately $10.5\,\text{L}$).

Plasma Fluid

The intravascular fluid component of extracellular fluid present in blood vessels, comprising $1/4$ of the total ECF (approximately $3.5\,\text{L}$).

Major ECF Cation

Sodium ($\text{Na}^+$), which is present in large quantities in extracellular fluid.

Major ICF Cation

Potassium ($\text{K}^+$), which is present in large quantities in intracellular fluid.

Major ECF Anion

Chloride ($\text{Cl}^-$), which is the predominant negatively charged ion in extracellular fluid.

Major ICF Anions

Phosphates and proteins, which exist in very large amounts inside cells.

Water Balance

The physiological state wherein daily total body water gain equals daily total body water loss (normally about $2300\,\text{ml}$ per day).

Insensible Water Loss

Unconscious water loss occurring through the respiratory tract and skin, totaling approximately $800\,\text{ml}$ per day under normal conditions.

Dehydration

A condition occurring when body water loss exceeds total body water gain.

Overhydration

A state of excess body water (water loading) occurring when body water gain exceeds total body water loss.

Gray Matter Water Concentration

The highest water content level among body tissues, containing $85\%$ water ($\text{H}_2\text{O}$).

Dentin Water Concentration

The lowest water content level among body tissues, containing $10\%$ water ($\text{H}_2\text{O}$).