Need help with a question on practice test for A&P

[stpauligirl]

If a red bloodcell is placed in a test tube of distilled water, the red bloodcell would be_______ to the distilled water?

a. hypotonic

b. isotonic

c. hypertonic

I know there is somebody very smart on this board who can answer this correctly.....it's giving me a headache

Your help is needed and very much appreciated.

Thank you

[HeartsOpenWide, RN]

Here are some examples:

1)0.28 m glucose- isoosmatic and isotonic ( to RBC ) - normal

2)0.15 m NaCl- isoosmatic and isotonic(to RBC) - normal

3)0.30 m NaCl- hypertonic-(to RBC) RBC shrink (crenate). H20 leaves.

4)0.33 m glycerin- isoosmatic but not isotonic- RCB swells and bursts. (Crosses membrane slow)

5)0.30 m urea- isoosmatic but not isotonic-RCB swell and burst faster than we can see. ( Crosses membrane fast)

What would happen if a diabetic's glucose increased well above the normal concentration? Well, the blood cells would have a high concentration of glucose, making then hypertonic to the outside of the cell. Water would enter the cell trying to dilute the high glucose, at the same time causing the cell to burst. The patient would become sick and could even go into a diabetic coma.

It helps to understand osmosis.

Osmosis happens naturally in our body. When we eat a lot of salt, some times we can see it by swollen fingers, but this only last a short time because our body balances it out to reach an isoosmatic state. Some people whose body does not use diffusion by osmosis properly can have what is called Edema, where their tissue swells all over and they have to take Rx pills to control it (Hydrochlorothiazide). or HCTZ