I have difficulty in understanding the reason why certain molecules can pass through phospholipid bilayers.
Firstly, I understand that the outer layer of the lipid bilayer is hydrophilic - my understanding is that they "like water" and can interact better with water.
Does this mean - because the hydrophilic surface are capable of hydrogen bonding - that's why they are able to absorb hydrophobic substances like F , O and N ?
They can absorb non-polar molecules.
They can absorb small uncharged molecules like H₂O and CO₂.
I'm not sure of the reasons behind 2 and 3 ...
And of course , vice versa ... (what can't pass through the lipid bilayer easily).
Any help would be appreciated!