This sounds very obvious, I know. I assume it doesn’t immediately stop the heart, and people can still survive even while being “brain dead”. So what exactly happens in the body to cause immediate death once a bullet enters the brain?
In: Biology
It isn’t. People can survive devastating injuries and loss of brain tissue loss. This is only true in movies and games. The brain is not immediately dead in contact with a bullet.
Malala Yousafzai was shot in the head and she’s alive. People can and do survive being shot in the head.
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The bullet will have multiple effects.
The first will be a high pressure wave. Water, what you are primarily made of, does not compress. So the force of the impact will cause powerful waves of force inside the skull. These force waves will shred neural connections.
Then you have the physical damage of the projectile passing through the brain tissue. It is probable the bullet (or bullet fragments) will be tumbling – shredding tissue as it passes.
Then you have the exit. The pressure wave will open a hole at the exit many times larger than the entry wound. Out of this hole will be thrown large quantities of destroyed brain tissue.
Your consciousness most likely ended at the moment the pressure wave scrambled your brain. Since you have no awareness after that point it really doesn’t matter when your heart stops or other tissues die. You effectively no longer exist.
A heart beat isn’t what determines if you’re alive or not. If your heart just stopped beating right now you’d live for quite a few minutes.
Why?
It’s the brain that is you. Your heart doesn’t think. It isn’t conscious. Your brain is.
Someone who is brain dead with a beating heart isn’t really alive. They’re just a corpse with a beating heart.
>I assume it doesn’t immediately stop the heart
Why not? The signal for your heart to beat comes from your brain. So does the signal for your lungs to breathe, and all the other body functions. You *can* survive a gunshot to the head depending on the bullet size and the path it takes. But if any of the many life-critical parts get hit (or liquified by shockwave), you’re done immediately.
If a bullet penetrate the skull, the hydraulic shock from headshot alone can severely damage the brain stem. And since the brain stem directly control breathing, the heart will quickly run out of oxygen and stop beating.
Your entire body is basically a vehicle and support system for your brain.
Everything that is ‘You’ lives here.
When a great trauma such as a gunshot happens the brain is mostly or completely destroyed and although otherwise perfectly functional the rest of the body no longer has a purpose and shuts down.
Think of it like a TV which relies on a power supply to function. If you shoot out the power supply the TV is still good, but without electricity it won’t function.
Not sure if anyone has mentioned already but you also have your control centers for respiration in your brainstem. So if that gets damaged your odds of survival are extremely low.
The *brain stem* is the part of the brain at the back and bottom of the skull, and merges with the spinal cord. It has critical roles in regulating cardiac function and breathing. Someone who is **brain dead** but still has a beating heart and may be still be breathing probably still has some brain stem function, but they are not showing any of the indications of higher brain function.
If the brain stem is destroyed by a traumatic injury, everything immediately required for life (breathing, heartbeat) stops. As a general rule, the further away the injury is from the brain stem, the more likely the patient is to survive, with varying levels of impact depending on where the damage is.
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