[Arnfinn]

Hi I have a problem I have been working with for a long time now, i really need some help.
Its about tne two hormones adrenaline and oestrone .

Their structural formulas can be found on those two links :

oestrone : http://www.3dchem.com/imagesofmolecules/Estrone.gif
adrenaline
http://upload.wikimedia.org/wikipedia/commons/thumb/3/36/Adrenalin_-_Adrenaline.svg/200px-Adrenalin_-_Adrenaline.svg.png

The problem is that i didnt really understood what the teacher said.
The problem,is that iam supposed to expalin (based on the chemical structure of those two molecules) why oestrone can pass through the fat-soluble cell-membrane, and why adrenaline cannot do it?

Maybe this is more about biology, the teacher said that the body has Cl(-) ( chloride ions) which can get combined to the
nitrogen atom, in adrenaline.Also he mention that estrone is more non-polarized, can this mean anything to the solubility
in this fat-soluble cellembrane?

He also mention that Oestrone get protonation at physiological pH at 7,4.

My questions are many. Well first of all, can estrone make any ionic bonds? He said that ionic bonds organize the water better, which makes better solubility than for dipole bonds for example. Can this have something to say for the estrone molecule and its solubility in fat?The Estrone molecule has some H-atoms. Can any of those make any ionic bonds with Chlorid ions? (maybe this is  not any ionic bond at all?)
If Chloride ions combine to the N-atom at adrenaline , will this make this substance less fat soluble?

Are anything of my arguments, which i mention above wrong? Well this is how i think  - can i explain this problem in terms
of the unpolarity of Oestrone (because it has 4 6-rings, and adrenaline just 1 ?

Is it correct that ionic bonds increase the fat solubility? or does it increase the water solubility? or has it nothing to say for this problem at all?

Can the chloride ions affect any of those two substances,? can it create ionic bonds with oestrone? Does it decrease the fat solubility for adrenaline?

are there any other ways to explain why oestrone can pass the fat solubility cellmembrane, and adrenaline doesnt?
I really appreciate all the help i can get!

[Yggdrasil]

At physiological pH the secondary amine in adrenaline (scientists refer to it as epinephrine) is likely to be protonated, making epinephrine a charged compound.  Charged compound cannot diffuse across the plasma membrane because charged compounds have low solubility in lipids. 

Estrone, on the other hand, has no groups that are likely to be charged at physiological pH.  As you mentioned, it is nonpolar and hence able to be solvated in the plasma membrane.

These chemical principles provide an explanation for the fact that epinephrine receptors lie on the plasma membrane while most estrone receptors are intracellular.