Pressure and Dehydration

If there’s one thing many are guilty of, it’s never drinking enough water. On surface level, It’s obvious dehydration does little justice, our bodies obviously require water to function and to maintain glowing skin! But what actually happens on the cellular level when we are dehydrated? 

First of all, our bodies are made up of water, where it’s 60 percent of body weight in males, and 50 percent in females. Water is vital. When dehydrated, the cell membranes become less penetrable, severely hindering the flow of nutrients and oxygen into the cell, and waste out. This waste accumulates and causes cellular damage. Cellular damage may lead to loss of function (of certain organs) and may lead to cancer if it aggregates.

The water which resides in our bodies falls into 2 categories, intracellular (inside cells) and extracellular (outside cells). The extracellular compartments include the water in the bloodstream and in the tissues (between tissue cells). Water may be transferred from intracellular to extracellular locations according to external conditions. The average person contains ⅔ of their water inside their cells. 

Each of these compartments consist of both water and salts. The salts, which are dissolved,  contribute to the osmotic pressure*.

Water Flow- Credit:

The osmotic pressure of the compartment is defined by the concentration of dissolved salts relative to other compartments. Osmotic pressure and concentration of salts are directly proportional ( greater concentration of salts, greater osmotic pressure). Under ideal conditions, there’s equilibrium of the osmotic pressure among the intracellular and extracellular compartments. However, in cases of dehydration, the concentration of salts decreases in one of the two compartments, prompting water to flow between the intracellular and extracellular compartments to re-equilibrate. 

There are 3 branches of dehydration, Isotonic dehydration, Hypotonic dehydration, and Hypertonic dehydration.

Isotonic dehydration refers to when there is a loss of water and the salt it contains. Salts are lost by vomit or diarrhea. Thus, there is a water depletion. To equilibrate the osmotic pressure again, some intracellular water flows into the extracellular compartment. Generally, they’re minor changes in osmotic pressure, but changes in water volume.

Hypotonic dehydration refers when body fluids contain a smaller concentration of dissolved salts than the cells. Since in osmosis, water follows its concentration gradient, water in the extracellular environment flow into the cells (because the cells have a higher concentration of salts). The cells swell, the membrane is stretched thin and can even lyse. Severe cases can even lead to cerebral edema.

Hypertonic dehydration is when the body loses more water than salts. Therefore, extracellular compartments possess a higher osmotic pressure, and water from the intracellular compartments flow out in order to balance the osmotic pressure. The cells shrink and lose their round shape. Cases of Hypertonic dehydration may lead to headache, weight loss, dry skin, and fatigue.

It is quite clear that dehydration has calamitous effects on our cells. Water shortages compromise cellular health and can cause severe health conditions. So hydrate, not only for external glow, but also to manage internal health!

Works Referenced

“Dehydration at the Cellular Level – MCEN4117 Dehydration.” Google Sites,

“Examples of Osmosis.” Diagrams Showing the Movement of Water through Cells,

O’Keeffe, Jillian. “What Happens to Your Cells When You Are Dehydrated?” Sciencing, 2 Mar. 2019,

The Editors of Encyclopaedia Britannica. “Dehydration.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 7 Dec. 2017,

Published by N

A high school student who is passionate about life sciences!

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