Osmotic Pressure






BASIC TERMS NEEDED TO UNDERSTAND OSMOTIC PRESSURE?

To understand what osmosis is, it is first necessary to understand a few other terms. If you already know the following terms, feel free to skip to the next section.

SOLVENT:
A usually liquid substance (such as water) that is capable of dissolving or dispersing one or more substances.

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SOLUTE:
A substance (such as sugar) that dissolves in a solvent. So if you poured sugar into a cup of water, the sugar would be the solute and the water would be the solvent.

SOLUTION:
The combination of a solute with a solvent, when the solute has been evenly dissolved in the solvent. An example would be when sugar (the solute) is evenly dissolved in a glass of water (the solvent).
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SEMIPERMEABLE MEMBRANE: A thin layer of tissue that allows some substances in, but not all. For example, the semipermeable membrane may allow a smaller substance in but not a larger one. Or it may only allow the solvent (such as water) to pass through, but not allow any solutes to pass through. Semipermeable membranes are widespread in the body and surround all cells.

WHAT IS OSMOTIC PRESSURE?

Osmotic pressure has the following meanings in the field of medicine:

1. The pressure that needs to be applied to a solution to stop the movement of a solvent into it, when the solution and solvent (such as water) are separated by a semipermeable membrane that only allows the solvent to pass through. In other words, although the semipermeable membrane would normally allow the solvent to pass through it, osmotic pressure prevents the solvent from passing through. Osmotic pressure can prevent osmosis, which is the movement of a solvent (such as water) through a semipermeable membrane, from a solution that has a lower concentration of solutes to one that has a higher concentration of solutes.

2. The force in which a solution attracts a solvent (such as water) through a semipermeable membrane. This definition of osmotic pressure is less commonly used than the first.

WHAT DOES OSMOTIC PRESSURE DEPEND ON?

Osmotic pressure depends on the amount of solute that is present in the solvent (such as water). It also depends on the temperature of the solution.

WHAT IS THE ORIGIN OF THE TERM "OSMOTIC PRESSURE"?

Osmotic pressure comes from the Greek word "osmos" meaning "impulse," the Greek word "ikos" meaning "pertaining to," and the Latin word "premere" meaning "to press." Put the words together and you have "pertaining to impulse to press."