Why can’t the brain be revived after death?


The other organs can be restarted post-mortem, what makes the brain so different?

In: Biology

Brain cells start dying almost instantly once they’re deprived of oxygen. You cannot revive a dead cell.

The brain consumes around 20% of the blood pumped out by the heart which tells us it’s heavily dependent on oxygen. Without the oxygen the cells start to die. One of the reasons brain death is irreversible is because of the lack of undifferentiated stem cells which could replace the dead cells.

Because that’s not accurate. Once they’re dead they’re dead. That goes for any organ. They’re not restarting hearts, etc where too many of the cells are dead. Some is ok for a lot of organs because the rest of the organ can take over. For the brain though it’s all important. Losing any of it is bad. Things like CPR keep the organs supplied with at least some oxygen and so keep them alive for longer in the hope that either the heart will spontaneously start beating again or medical intervention can take place.

The brain though requires a lot of oxygen so even after successfully getting the heart going after a bout of CPR the brain is quite often damaged. This is because due to the high oxygen needs of brain cells they begin to die after just a few minutes. Cells of other organs can last longer.

The brain begins to experience permanent damage after ~3 minutes of someone’s heart not pumping oxygenated blood to it, and it’s permanently dead after ~7 minutes. This is why CPR and AEDs are so important. Your other organs are a lot more resilient. So if someone is dead at all, their brain was the first thing to become permanently non-salvageable.