How does electrolytes affect osmosis

Biological systems constantly interact and exchange water and nutrients with the environment by way of consumption of food and water and through excretion in the form of sweat, urine, and feces.

Without a mechanism to regulate osmotic pressure, or when a disease damages this mechanism, there is a tendency to accumulate toxic waste and water, which can have dire consequences.

Mammalian systems have evolved to regulate not only the overall osmotic pressure across membranes, but also specific concentrations of important electrolytes in the three major fluid compartments: blood plasma, extracellular fluid, and intracellular fluid.

Since osmotic pressure is regulated by the movement of water across membranes, the volume of the fluid compartments can also change temporarily.

Because blood plasma is one of the fluid components, osmotic pressures have a direct bearing on blood pressure. Electrolytes, such as sodium chloride, ionize in water, meaning that they dissociate into their component ions. Electrolytes are lost from the body during urination and perspiration. For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration.

Osmotic pressure is influenced by the concentration of solutes in a solution. It is directly proportional to the number of solute atoms or molecules and not dependent on the size of the solute molecules. Because electrolytes dissociate into their component ions, they, in essence, add more solute particles into the solution and have a greater effect on osmotic pressure, per mass than compounds that do not dissociate in water, such as glucose.

Water can pass through membranes by passive diffusion. If electrolyte ions could passively diffuse across membranes, it would be impossible to maintain specific concentrations of ions in each fluid compartment therefore they require special mechanisms to cross the semi-permeable membranes in the body.

This movement can be accomplished by facilitated diffusion and active transport. Facilitated diffusion requires protein-based channels for moving the solute. Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient.

In order to calculate osmotic pressure, it is necessary to understand how solute concentrations are measured. The unit for measuring solutes is the mole. One mole is defined as the gram molecular weight of the solute. For example, the molecular weight of sodium chloride is Thus, one mole of sodium chloride weighs The molarity of a solution is the number of moles of solute per liter of solution. The molality of a solution is the number of moles of solute per kilogram of solvent.

If the solvent is water, one kilogram of water is equal to one liter of water. Go to the footer. Rehydration What are electrolytes ions? Electrolytes produce ions and enable the body to function Body fluid contains electrolytes, chemicals which, when they dissolve in water, produce charged ions.

Potassium ions Transmit nerve signals, and contract muscles including the heart, etc. Magnesium ions Contract muscles, form bones and teeth, activate enzymes, etc. Electrolytes are lost from the body during urination and perspiration. For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration. Osmotic pressure is influenced by the concentration of solutes in a solution.

It is directly proportional to the number of solute atoms or molecules and not dependent on the size of the solute molecules.

Because electrolytes dissociate into ions, adding relatively more solute molecules to a solution, they exert a greater osmotic pressure per unit mass than non-electrolytes such as glucose. Water passes through semi-permeable membranes by passive diffusion, moving along a concentration gradient and equalizing the concentration on either side of the membrane. The unit for measuring solutes is the mole. One mole is defined as the gram molecular weight of the solute.

For example, the molecular weight of sodium chloride is Thus, one mole of sodium chloride weighs The molarity of a solution is the number of moles of solute per liter of solution. The molality of a solution is the number of moles of solute per kilogram of solvent. If the solvent is water, one kilogram of water is equal to one liter of water. The unit of milliequivalent takes into consideration the ions present in the solution since electrolytes form ions in aqueous solutions and the charge on the ions.

Thus, for ions that have a charge of one, one milliequivalent is equal to one millimole. For ions that have a charge of two like calcium , one milliequivalent is equal to 0.

Another unit for the expression of electrolyte concentration is the milliosmole mOsm , which is the number of milliequivalents of solute per kilogram of solvent.

Body fluids are usually maintained within the range of to mOsm. Persons lost at sea without any fresh water to drink are at risk of severe dehydration because the human body cannot adapt to drinking seawater, which is hypertonic in comparison to body fluids.

Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as stenohaline. About 90 percent of all bony fish are restricted to either freshwater or seawater. They are incapable of osmotic regulation in the opposite environment. It is possible, however, for a few fishes like salmon to spend part of their life in fresh water and part in sea water. Organisms like the salmon and molly that can tolerate a relatively wide range of salinity are referred to as euryhaline organisms.

This is possible because some fish have evolved osmoregulatory mechanisms to survive in all kinds of aquatic environments.

When they live in fresh water, their bodies tend to take up water because the environment is relatively hypotonic, as illustrated in Figure 2. In such hypotonic environments, these fish do not drink much water. Instead, they pass a lot of very dilute urine, and they achieve electrolyte balance by active transport of salts through the gills.