I don't really understand this. I was reading Jenny83's thread about fainting at the sight of blood/whatever other bodily fluids you see and I was curious to know if anyone knew <i>why</i> exactly people faint? Is there some kind of physiological response that triggers it? I know hypoglycemia/hypotension, but why when you see blood/"guts?" Or is it all psychological, like relating to the patient's own pain from your own experiences?