system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: As opposed to movies, how long does a lethal gun or knife wound take to kill?

I'm not trying to be morbid, but it's slightly annoying how movies portray any sort of torso wound to cause someone to fall to the ground and instantly die with nothing more than a slight "Argh."  I'm pretty sure that even chest wounds take a bit to kill, although shock might kick in faster?  
Without being overly graphic or morbid, can someone explain what happens when a fatal wound occurs?
gpt
Even when shot or stabbed in the heart a person will quite often remain on their feet for some time.  Sometime here means seconds and not minutes or hours.  This is quite often enough time for them to fight back and even kill their attacker (this is why cops will shoot you until they run out of bullets).  Even after collapse it will take time for the person to bleed out enough to deprive the brain of oxygen.  This means that you will not fall over totally dead within seconds of being shot in the torso.  

If it's not a hit to the heart it can take a lot longer to die.  The ol' getting shot or stabbed in the stomach and dying within seconds is pretty much total bullshit.  Historically gut wounds were seen as the worst because they took so long to die from and were very painful. Think of the soldier in the opening scenes of Saving Private Ryan who is laying on the beach screaming for his mother after he's been disemboweled.  That's more like it.

The only time you're going to instantly collapse is when the central nervous system is hit.  In a torso hit that means the spinal cord.  

In fact, if you read a look of accounts of war, or watch docos, you'll come across stories from soldiers where they were shot, sometimes multiple times, in the torso and didn't even realise for a while.