Are you good at biology?! Please give this one a try...?

Question

Are you good at biology? if so please give this one a try!?
1) why is it important that solutions added to the blood stream must be isotonic with the blood plasma?

2) why does the salt runoff from winter roads kill nearby plants? please explain this clearly, i think it has to do with osmosis

THANKS :)

Answer 1

Blood plasma is a complex liquid and tiny solids that we depend on for life and messing with that solution even a tiny bit can result in death. A recent development that won't do that is an artificial blood supplement that is smaller than the size of a red blood cell. It is white and made out of chlorofluorocarbons (yes, the same class of chemicals that punched a hole in the ozone layer). It is reactive with oxygen and can carry it through smaller spaces, like where the blood is constricted in the heart or brain. This can be the difference between losing that part of the body or not.

Also according to the definition of osmosis if your solution IS NOT isotonic then you risk flooding the cells with too much water, or draining them of valuable water. The human body doesn’t want to use osmosis to transport material because it can create a problem with too much flow.

According to Wikipedia: http://en.wikipedia.org/wiki/Isotonic
"Isotonic literally translates to equal tension. The term is used in several different contexts.

Isotonic solution bears the same chemical resemblance of the body’s blood, plasma and tears. All fluids in the body have a certain concentration, referred to as osmotic pressure. The body’s common osmotic pressure, which is isotonic, allows a consistent maintenance of body tissues. In order for a substance to be absorbed and used in the body’s metabolism, it must be transported in an isotonic state."

Which, is basically saying the stuff you put into the blood stream has to be just like the body's blood, or tears, which explains why most IVs are a saline (salt) solution. You don’t want to promote an osmosis situation so the balance of being isotonic is important to keep the cells from being flooded or drained.

As far as road salt injuring plants near the road; you are right. Osmosis is how a plant sucks up its water to reach the leaves. Too much salt in the soil will suck up some of that valuable water, but more importantly the super saline solution will not be good for the plant, just as drinking pure sea water is harmful for humans.

According to Wikipedia: http://en.wikipedia.org/wiki/Osmosis
"Osmosis is the net movement of water across a partially permeable membrane from a region of high solvent potential to an area of low solvent potential, up a solute concentration gradient. It is a physical process in which a solvent moves, without input of energy, across a semi permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations. Osmosis releases energy, and can be made to do work, as when a growing tree-root splits a stone...

In unusual environments, osmosis can be very harmful to organisms. For example, freshwater and saltwater aquarium fish placed in water of a different salinity than that they are adapted to will die quickly, and in the case of saltwater fish, rather dramatically. Another example of a harmful osmotic effect is the use of table salt to kill leeches and slugs."

This explains exactly what I, and you, were talking about; to much salt is going to cause problems.

In addition Isotonic is involved in osmosis as well:
According to Wikipedia: http://en.wikipedia.org/wiki/Osmosis
"- If the medium is hypotonic — a dilute solution, with a higher water concentration than the cell — the cell will gain water through osmosis.
- If the medium is isotonic — a solution with exactly the same water concentration as the cell — there will be no net movement of water across the cell membrane.
- If the medium is hypertonic — a concentrated solution, with a lower water concentration than the cell — the cell will lose water by osmosis."

Answer 2

It is important to have solutions be isotonic so the water within the blood stream/cells will not change. If you were to add a soltuion that was hypo or hypertonic relative to the blood stream, the tendanacy for water movement will be toward the solution with a lower water concentration. You would cause dehydration or over hydration if you did not make sure the solution was isotonic

As for the plants, they are killed probably because the water is leached out from their roots or from the surrounding soil as the salt has a tendancy to draw water out of cells/roots/etc.... The plants get dehydrated.