How is the cell protected from the hydrolase enzymes of the lysosomes? - (Oct/27/2011 )

Good night everybody...
I would like to ask a little question about lysosomes...
we all know that lysosmes are bounded only by a single membrane, and we also know that lysosmes have hydrolase enzymes that are capable of hydrolasing any substance in the cell...but the question is: how are the cell components including the membrane of the lysosmes are protected from these enzymes..
one of the reasons is that these hydrolase enzymes are only activated in an acidic environment, ph is 4-5 in the lysosmes...and so they can't work at a neutral ph of 7 in the cell...another reason is the carbohydrate layer at the inner part of the lysosmal membrane that protects the membrane of the lysosmes from these enzymes.
are there any other reasons?
Thanks so much

a bit late, but yes. Those are the reasons.
I cant think of any other.