Body Fluids and Fluid Compartment

Question 1

Discuss the two major fluid compartments:
(1) intracellular fluid
(2) extracellular fluid

Answer 1

(1) Intracellular fluid is the fluid present inside cells. It forms 40% of the body weight and 2/3 of the total body water; it’s about 28 litres (in a 70kg man). It contains more potassium, magnesium, phosphates, sulphates, and proteins than the extracellular fluid.

(2) Extracellular fluid: This is the fluid present outside body cells. It forms 20% of the body weight and 1/3 of total body water. It is about 14 liters (in a 70kg man). It contains more sodium, chlorides and bicarbonates. Extracellular fluid is divided into:
(i) Plasma: 5% of body weight; 25% of ECF; 3 litres
(ii) Interstitial fluid: 15% body weight; 75% of ECF; 11 litres
(iii) Transcellular: less than 1% of body weight; includes CSF, intraocular fluid, synovial fluid, peritoneal fluid, and pericardial fluid