Step-by-step explanation:
When one's life is in danger, it causes them to do things they wouldn't normally be able to do.
This stimulates the, "fight-flight-or-freeze" response. Three hormones are released into the bloodstream, adrenaline, cortisol, and norepinephrine.
It is what gives you adrenaline rushes on life threatening situations, or even just scary situations. When someone is scared and their teeth chatter, it is because of these three hormones being released.