I have totally confused myself about tonicity of solutions....

BacktotheBeach, ADN, BSN, RN · Jul 25, 2010

HypErtonic solutions will crEnate a cell (take water from it.) Remember the E in hypertonic and the E in crenate. So hypertonics have a lower water content--more solute less water

HypOtonic has an O, it will expand, or lyse the cell. Picture an O inflating. Hypotonic solutions have a higher water content.

Jjearkwein · Jul 25, 2010

remember this, "water moves from higher concentration to lower concentration and stops when the concentration is equal" from this derived the phrase, "where Na goes, water follows"

so if a solution contains more Na(hypertonic), water from the cell will move out of the cell(cell will shrink)...

and inversely in hypotonic solutions(cell will swell)...

Music in My Heart · Jul 25, 2010

My question is: do hypertonic solutions contain a higher or lower concentration of H2O than intracellular fluid?

Your terminology is messed up. It's not about the "concentration" of water... it's about the concentration of the solution (that is, how much solute is dissolved in the water).

Hypertonic solutions are highly concentrated (think salt water).

Hypotonic solutions are lowly concentrated (think deionized water).

TheSquire, DNP, APRN, NP · Jul 25, 2010

Hyper- = high

Hypo- = low

A basis in greek and latin vocabulary will help you a lot in nursing school.

Intern67 · Jul 26, 2010

Your terminology is messed up. It's not about the "concentration" of water... it's about the concentration of the solution (that is how much solute is dissolved in the water).[/quote']
I think this is the only response that really gets to the heart of the matter.
I'll repeat my standard drone about taking the time to learn the "whys" of the situation and not only going off of mnemonics. Memory tricks are great for quick recall of fairly easy and straightforward questions but will not help you much on the stumpers.

Music in My Heart · Jul 26, 2010

I think this is the only response that really gets to the heart of the matter.
I'll repeat my standard drone about taking the time to learn the "whys" of the situation and not only going off of mnemonics. Memory tricks are great for quick recall of fairly easy and straightforward questions but will not help you much on the stumpers.

When I tutor, one of the things that I preach is the understanding and the precise usage of terminology. If one is confused about the terms, one will be confused about the concepts and then about the topic in general.

JROregon, ASN, BSN, RN · Jul 26, 2010

Yes, yes, yes, it is about the concentration of solute.

Hyper - higher concentration of solute

Hypo - lower concentration of solute.

Yes, it's true that water is attracted to the higher concentration of solute and will move through a membrane in order to equalize the concentration on both sides of the membrane.

Yes, a cell will crenate when water is pulled out of that cell because there is a higher solute concentration in the solution surrounding the cell. The cell will lyse when there is a higher concentration of solute in the cell compared to the solution surrounding the cell.

turnforthenurse, MSN, NP · Jul 28, 2010

HypOtonic has an O, it will expand, or lyse the cell. Picture an O inflating. Hypotonic solutions have a higher water content.

This is a great way of remembering this.

Hypertonic - think hyper = high. They have a lot of solute, less water. Will cause the cells to shrink.

Hypotonic - think hypo = low. They have less solute, more water. Will cause the cells to swell.

JROregon, ASN, BSN, RN · Jul 28, 2010

Okay, if we are looking at a cell that is in a hypertonic solution, the water will leave the cell and the cell will shrink or crenate.

When calling anything hypertonic or hypotonic, you need to compare it with something else. Like in nursing, if you are giving someone a hypertonic solution, you are comparing it to the normal extra cellular fluid in the body. Always a comparison.