  Tension in lipid membranes is often controlled externally, by pulling on the
boundary of the membrane or changing osmotic pressure across a curved membrane.
But modifications of the tension can also be induced in an internal fashion,
for instance as a byproduct of changing a membranes electric potential or, as
observed experimentally, by activity of membrane proteins. Here we develop a
theory which demonstrate how such internal contributions to the tension are
moderated through elastic stretching of the membrane when the membrane is
initially in a low tension floppy state.
