Hypertonic/Hypotonic/Isotonic

[SarahT]

Hey everyone. I'm new to posting, but have chatted a bit in the past.

I'm just starting my 3rd semester (EMT-I) of class, and tonight we talked about IV administration. They showed us a video about it, where hypertonic/hypotonic/isotonic solutions were briefly mentioned. The video explained it in a way that clicked, but I don't remember which is which now. She said that in one of them, it brings fluid from the outside in, and another gives fluid from the inside out. (Example being trauma/blood loss- macrodrip with Ringer's and N.S. to add volume and buy a little time)

I know what the medical definitions are, but as it is the first day studying it, I'm boggled. We will be studying it more in the next couple of weeks, but it's always good to understand it before class and not have that "i'm so friggin' confused" look in your eyes. Does anyone have an easy way to remember this?

If anyone has any helpful advice, I would appreciate it. Thanks in advance!

P.S.- Before the "Search nazi's" get me, I did a search, and this is what it brought up.

Educational Forum/Thread Game

The roll of D5W in CHF patients

IV Solutions You Carry

Coconut IV

Google brought up a few other ways of defining it, none of which I really understand at this point.

[akura]

an example of an isotonic solution would be normal saline solution. Isotonic basically means the solute concentration in the saline and in the bloodstream are equal so there would not be a shift in the concentration gradient.

hypertonic solution would be like D50W. Lots of sugar molecules in the D50W, not as many in the bloodstream. This will cause water to move from the interstitial spaces into the bloodstream in order to equalize solute concentration on both sides of the venous system.

hypotonic solution would be one that has less molecules in the solution as opposed to the concentration of molecules in the interstitial space. This would cause the shift of water from the venous system into the interstitial space..

hope that makes sense =D

[fiznat]

Osmosis can be summed up by simply saying "water follows salt."

The idea is that water moves so that the concentrations on both sides are equal. Water flows towards a hypertonic solution because that side has more solute ("salt"), which needs to be balanced out by more water.

A cell placed in a hypertonic solution --- water flows out of the cell (towards salt), cell shrinks

A cell placed in hypotonic solution --- water flows into the cell (towards the salt in the cell), cell blows up

A cell placed in an isotonic solution --- no net movement of water (already balanced), cell remains unchanged

Notice that there are always 2 fluids used for comparison. I used "the fluid within the cell" and "the fluid outside of the cell." The user above used "the fluid in the vasculature" and "the fluid outside of the vascularture (the intersticial)." It doesnt matter which example you use-- the point is that you have two volumes of fluid with varying concentrations of solute, separated by a semi-permeable membrane through which water can flow.

[Emilea PA C]

Coming from a biochem major in "real life" hypotonic/hypertonic/isotonic are difficult terms to get a handle on! First, they are relative....meaning that just because Solution A is hypotonic to Solution B, Solution A may be isotonic to Solution C.

Basically, you must first understand osmosis. Osmosis is the diffusion of water across a gradient that does not require the use of energy. Water always flows from higher concentration to lower concentration.

If you understand those last two sentences, read on....if not, go back and reread them until you understand them!

Secondly, you must understand solutions. The solute is the material being dissolved. The solvent is what is doing the dissolving. For examply, salt water.....the solute is salt, the solvent is water.

Hypotonic - this solution has less solute than the comparitive solution (see 2nd sentence....these terms are relative); a hypotonic solution will receive solution across the gradient from a hypertonic solution.

Hypertonic - this solution has more solute than the comparitive solution; a hypertonic solution will give solution across the gradient to a hypotonic solution.

Isotonic - these two solutions are equal in concentration. Equilibrium has occured and no net movement across the gradient will be observed.

Hope that helps, Emilea

[JPINFV]

^

Err, you're confusing osmosis and simple diffusion. Water goes from hypotonic to hypertonic while the solutes (if able to cross the membrane) goes from hypertonic to hypotonic. Your way would result in the hypertonic solution losing solvent, thus becoming more hypertonic.

[Ridryder 911]

Although it is all important more important is the osmolarity level after it enters the cell if it is iso, hyper, hypo... which there is very little difference in IV fluids in a short period of time and the small amount of fluids administered. Again, although it is important to know the what the over all ratio is.

R/r 911

[DwayneEMTP]

Hypotonic - this solution has less solute than the comparitive solution (see 2nd sentence....these terms are relative); a hypotonic solution will receive solution across the gradient from a hypertonic solution.

Hypertonic - this solution has more solute than the comparitive solution; a hypertonic solution will give solution across the gradient to a hypotonic solution.

Unless I'm having brain fade (which is common) I think you got it turned around in the second half of these two sentences.

(Then what JPINFV said)

Dwayne

[AnthonyM83]

This always brings up confusion, even for some teachers who normally know their stuff...it's just easy to mix up what the hyper/hypo is in reference to.

The key for me is adding the word "solution" after each term.

People always forget if it's the solution that's hyper/hypo or if it's the solvent (tonic) that's hyper/hypo (later one is true).

Think of tonic (as in tonic water) as something/particles you mix into water to make a specific drink (solution).

A hypertonic solution will have a relatively hyper amount of tonic particles in the solution.

(and of course it's all relative to whatever you're comparing it with)

So remember:

HyperTonic Solution - Higher tonic/particles in the solution

HypoTonic Solution - Fewer tonic/particles in the solution

IsoTonic Solution - Same amount of tonic/particles in solution

[Emilea PA C]

OK, guys and gals.....if you read the first sentence in my post you will see that I come from a biochem background! My post refers to the process not the terms!

Perhaps this will help (and again, hyper/hypo/iso is VERY difficult to get a grasp on, simply because it is relative.....see, I even confused you old pros on here!!)

You have three solutions. Each solution is 100 mL of distilled water.

Solution A has 4 tsp NaCl dissolved.

Solution B has 2 tsp NaCl dissolved.

Solution C has 4 tsp NaCl dissolved.

Sol A is hypertonic to Sol B. Sol B is hypotonic to Sol A. Sol A and Sol C are isotonic.

If you were to place a concentration gradient (ie, plasma membrane) between these solutions you would observe the following:

• Sol A and Sol B ---> the volume of Sol A will increase, the vol of Sol B will decrease.

[*]Sol A and C ---> no net change will be observed

[SarahT]

Thanks so much everyone, I appreciate the replies and understand it much better. Tonight if she calls me out in class, at least I will have an understanding of what I'm talking about, instead of "cookbooking" it.

Thanks again!