Hypothetically, if the threshold is normally -60mV, but now we have too much calcium on board, our threshold is now -50mv. That is a difference of 40mV that the cell has to account for in order to depolarize. In skeletal muscle, this can cause weakness, fatigue, etc. Too little calcium will cause the threshold to become more negative (gets closer to the resting membrane potential).
OK, this is probably going to come with you laughing at me... Once in a while I wake up with the back of my head sweating, and it`s more common when I take a nap during the day.
Headache Trigger #1: Heat If your head starts pounding during a sunny day in the bleachers, it may be due to the heat, not because your favorite team is losing. One theory behind a headache brought on by heat is that the bodyâs attempt to cool itself by sending more blood to the skin deprives the brain of oxygen.