Jellybean, in every handgun shooting I've worked on in which a bullet clipped the aorta, heart, brain, or spine (in descending order of frequency of hits in the more-than-200 handgun killings I've done some type of work on), the shootee immediately ceased aggressive action.

That might not always be the case and every shooting is different, but it happens so frequently that I tell my friends to study human anatomy and target the heart/aorta or brain (as opposed to the more nebulous "center of mass" or "thoracic triangle" or whatnot) in the event of need, and to practice in such a way as to be able to hit targets of the right size at defensive differences.

Here's a link to Gray's Anatomy online:

Gray, Henry. 1918. Anatomy of the Human Body

cheers, erich