Quick question about osmotic pressure

[161468]

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This should be quite easy. If solution A has a higher concentration of solute than solution B, then osmotic pressure of solution A is higher right?

I am basing this on the equation for osmotic pressure, P = iCRT, where iC is the osmolarity of the solution. The higher the concentration, the higher the pressure. However, it seems some of my practice questions imply that the higher the solute concentration, the lower the osmotic pressure of the solution.

 

[chad5871]

No, I think you're right. Osmotic pressure is proportional to the concentration of the solute.

 

[apoptos]

Because it will attract more water, giving it a 'outward' pressure?

How does this relate to hydrostatic pressure, and how can you determine which is stronger?

 

[161468]

Because it will attract more water, giving it a 'outward' pressure?

How does this relate to hydrostatic pressure, and how can you determine which is stronger?

I was thinking that osmotic and hydrostatic pressure are opposite, meaning that if two solutions separated by a semipermeable membrane, then the solution with a lower solute concentration will have a higher hydrostatic pressure (because the water will flow out of it) but a lower osmotic pressure (because it is less likely to "attract" water).

 

[nihargala]

This should be quite easy. If solution A has a higher concentration of solute than solution B, then osmotic pressure of solution A is higher right?

I am basing this on the equation for osmotic pressure, P = iCRT, where iC is the osmolarity of the solution. The higher the concentration, the higher the pressure. However, it seems some of my practice questions imply that the higher the solute concentration, the lower the osmotic pressure of the solution.

Osmotic pressure is like the "pulling of water" force of a solution. Obviously, more concentrated solutions (i.e. more solute) will pull more water than dilute solutions. Therefore, more concentrated solutions have a higher osmotic pressure.

Hydrostatic pressure is the "pushing of water" force. Hydrostatic force can be see in the glomerulous, where the blood pressure forces filtrate into the renal tubules.

I hope you get it now if you hadn't before..

 

[mrmilad]

Sooo....


Hydrostatic pressure of a solution surrounded by an impermeable membrane = X ( Pressure pushing out )

Osmotic pressure of the same solution is = Y ( Pressure pulling in)

The pressure that is felt by the system Z =

Z = difference between X and Y.

So if X = 10 mmHg and Y = 5 mmHg

Z = 5 mmHg OUT of the solution


👍

 

[chad5871]

Sooo....


Hydrostatic pressure of a solution surrounded by an impermeable membrane = X ( Pressure pushing out )

Osmotic pressure of the same solution is = Y ( Pressure pulling in)

The pressure that is felt by the system Z =

Z = difference between X and Y.

So if X = 10 mmHg and Y = 5 mmHg

Z = 5 mmHg OUT of the solution


👍

Pretty sure that's right. I certainly hope it is! 👍

 

[mrmilad]

Oh yes it is. ;p. I hope you know what that means.

 

[chad5871]

Oh yes it is. ;p. I hope you know what that means.

Yes I do and that makes me very happy! 😀 Thanks for the extra boost of confidence!

 

[Foghorn]

Sooo....


Hydrostatic pressure of a solution surrounded by an impermeable membrane = X ( Pressure pushing out )

Osmotic pressure of the same solution is = Y ( Pressure pulling in)

The pressure that is felt by the system Z =

Z = difference between X and Y.

So if X = 10 mmHg and Y = 5 mmHg

Z = 5 mmHg OUT of the solution


👍

Don't you mean "semi-permeable" membrane where only solvent, such as water, can flow through?

 

[nihargala]

Sooo....


Hydrostatic pressure of a solution surrounded by an impermeable membrane = X ( Pressure pushing out )

Osmotic pressure of the same solution is = Y ( Pressure pulling in)

The pressure that is felt by the system Z =

Z = difference between X and Y.

So if X = 10 mmHg and Y = 5 mmHg

Z = 5 mmHg OUT of the solution


👍

That's definitely right... and you see that as blood flows from the arteriole end of the capillary to the venule end. At the arteriole end, the hydrostatic force (HF) is greater than the osmotic pressure (OP), therefore fluid is forced out of the capillaries into the interstitial tissue. (From there, excess fluid build up in the interstitial tissue is drained into the lymph system).. At the venule end, however, the OP is greater than the HF, therefore fluid is reabsorbed into the capillaries from the interstitial tissue.

Kudos.