Batsman stopping the ball hitting his wicket.

Is the batsman out if a) he deflects the ball away from his wicket after playing it. i.e. with bat, foot etc to avoid being 'played on' b) if he, when out of his crease, 'accidentally' stopped the ball hitting his wicket by interposing any part of his body on the ball's flight path?The logistics to me is similar to an lbw decision.