Eli5: Why can broken bodies (aka corpses) not be ‘fixed’ like machines?


If a machine breaks, you can fix it, even if it means replacing a part, and you can do this AFTER it’s stopped working. You can replace a part in a body to, like an organ, but only BEFORE the body stops working. Why is this? What do we lose when we die that cannot be replenished (except in the seconds/minutes after death in certain circumstances)?

In: Biology

Every starts falling apart. The blood vessels and veins lose integrity, cells stop reproducing, bacteria suddenly have nothing to stop them from just consuming all of it. The brain is the main player, and it rots. There’s no way to fix the deterioration of the brain. Even seconds after death, there’s been too much damage to the brain, and we have no way at all to fix something that complicated.

We cannot create new brain tissue, or replace dead brain tissue. We do not understand how the brain operates well enough. Once enough living brain cells die there isn’t anything to be done.

It comes down to the brain. We can make (manufacture) parts to fix a machine. We can even replace most parts in a human body. But we don’t know how to grow a brain or replace (transplant) one brain for another. The connections are too many and too complicated. Once the brain loses oxygen, the tiny parts of it (cells) start to die. We don’t know how to create a living cell. We don’t know how the brain stores our memories or information. In many ways medicine is in its infancy.

You can not fix any machine. For example if something brakes in an engine so oil is no longer circulating this will destroy almost every component of the engine due to the rapid wear of dry components rubbing against each other and metal debris from the wear getting between components to cause even further wear. So if this happen you can not fix the engine but you might salvage some parts for use in other engines.

It is similar with humans. If the heart and lungs stop working then there is no longer any oxygen being transported to the cells and the cells start decomposing. This happens to every cell at once. Unless you are able to get the blood circulation up again to transport oxygen to the cells they will become damaged beyond repair after just a few minutes. You might just be able to save some organs but some of the more sensitive organs such as the brain is quickly beyond repair.

Life is a bio-mechanical machine, and current science has a long way to go before we truly understand bio-mechanics. Maybe someday.

There are many stages of death, with the first stage being called Pallor Mortis. Pallor Mortis sets in almost immediately after death. This is when a collapse of the circulatory system happens and blood vessels themselves cannot function anymore.

There are some rare instances of people being reanimated within a few minutes after clinical death, before Pallor Mortis has set in. There are also documented cases of people being brought back from death 40 minutes or more later, but this always involves very cold temperatures such as drowning in cold water. The cold slows down the onset of Pallor Mortis and the body has a better chance of being revived.

Our current medical technology is not enough to revive a dead body. Especially cellular death.

Look at it this way:

On an engine, you shut the car off before doing any repairs for your own safety. The car is now “dead”

You then do the repair, and you can start the engine.

With humans, we can EASILY swap parts while the engine is off (dead)

The problem is, we haven’t found the key to turn the engine back on yet.

So when a Dr does a transplant, it’s like changing parts on a engine while it’s running.

Once the engines off, we don’t know how to restart it.