00:00 / 00:00
Movement of water between body compartments
0 / 15 complete
Water is the key to life - It has very unique properties like being an amazing solvent, which means that it’s easy for solutes to dissolve into water.
As a result, water can carry essential nutrients to our cells as well as toxins or waste products away from our cells to be excreted out of our system.
On average total body water in a person is about 60% of their body weight.
Extracellular fluid is the first to be lost and makes up fluids like gut fluids, sweat and other secretions.
The extracellular fluid is made up of different solutes, the major cation being sodium (Na+) and the major anions being chloride (Cl-) and bicarbonate (HCO3-).
Each compartment has a specific solute concentration measured in mOsm/L or osmolarity, which is the number of osmoles within a liter of solution.
Now remember that an osmole refers to the individual ions within a solution. So for example, NaCl splits apart in water to become Na+ and Cl-, so a solution of 1 mmol/L of NaCl is actually 2 mOsm/L. Normally, osmolarity in the intracellular fluid and extracellular fluid is equal.
If either side ever has a few more solutes, than water will flow in that direction to lower the concentration slightly and maintain the balance. This process is called osmosis.
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.