Following through on a draw

[jacaranda]

OK I have a question....
Say you're on a draw after the flop and you calculate that you have a decent chance of catching because you still have 2 cards to see. The turn card brings no help and you've already paid to see it. Do you stick with your original pot odds before the turn card? Or do you adjust it now because there's only one card left? In other words lets say your odds of catching with 2 cards was about 7 to 1 and with one card, 10 to 1. Would you still call a bet after the turn that was only giving you 7 to 1 pot odds just to stick with your original plan? Or would you demand 10 to 1 at the river?

This is of course assuming you're not a donkey and actually figure in pot odds to your calling decisions.