Importance of maintaining the concentration of water in cells question! (1 Viewer)

[s-tressed]

In the process of refining my notes and have come to the realization that I don't understand something that I have written ..

I summarized from this extract (pg71 of biology in focus):

Changes in water concentration
lead to corresponding changes in solute
concentration in cells: the relative
concentration of solutes: water in cells
determines the osmotic pressure
of cells. Water enters and leaves cells
by the process of osmosis and the
net direction of water movement is
dependent on the osmotic gradient—
water moves from a high to a low
water concentration through the
selectively permeable cell membrane.
The movement of water into and out of
cells therefore depends directly on the
concentration of solutions both inside
and outside the cells.

I feel like the explanation is saying the opposite of the part in italics.. Maybe i'm just a little slow today.

Help appreciated

 

[jananee]

I am assuming you are answering this dot point, "Explain why the concentration of water in cells should be maintained within a narrow range for optimal function"?

Water concentration needs to be maintained at a certain level as this coordinates the osmotic gradient and hence the concentration of solutes in the cell (basically the stuff in italics). Therefore if there is too much water in the cells (the gradient is higher here and lower outside the cell), the solute conc is lower and the water will move out of the cell to make the solute conc higher (and vice versa). So your last line "the movement of water into and out of cells...depends on conc. of solutions" and the italicised line are basically the same as water determines the conc of the solution and therefore determines the changes that need to be made to maintain homeostasis.

I have absolutely no idea if that made sense but if it didn't, just tell me and I will try to explain it clearer