People who have fainted - what caused it?

Seeing blood. I cut my hand on a corn beef tin, walked out of the kitchen to find the first-aid box then passed out and smacked my head on the radiator, ending up in the hospital. They pulled a nurse out of the children's A&E especially, apparently because it was facial and she was really good at stitching but I think it might have been more because I was freaking out and telling everyone I was going to look like Frankenstein's sister and needed a babies nurse lol. The scars not too bad lol. It was a tad over dramatic. 😂