What happens to your body after you die, in 13 steps

• The way the body breaks down after death is a gruesome but fascinating process.
• This process has taught scientists about tracking killers, near-death experiences, and how to cheat death.

There's no fighting it; each of us will die at some point. What happens next is a fascinating — if frightening — natural process.

Without preservation techniques like embalming or mummification, your body slowly begins to decay the second your heart stops beating.

Here's how the complete, gruesome process plays out.

Within seconds of death, your brain activity surges, then stops

Scientists who recorded brainwaves of dying patients found that brain activity surges moments after the body gives out.

This may provide some explanation for why people with near-death experiences recall their life flashing before their eyes.

The body temperature drops

Body temperature is controlled by the brain. As this organ stops working, the body's temperature will start dropping until it reaches room temperature.

How fast this happens depends on many factors like external temperature, clothing on the body, and fat content of the body. But the benchmark is that the body loses about 1 to 2°F per hour.

This stage, called algor mortis, is the first of the early postmortem changes, well-known by forensics experts who use it to determine time of death.

Within minutes, cells in the body start breaking down

Cells need oxygen to survive. Without blood pumping through the body taking carbon dioxide away, the inside of the cell becomes very acidic.

That makes compartments inside the cells break down, releasing toxic chemicals that were previously contained. These eat the cell from the inside out. This process is called autolysis.

If it's very cold, autolysis can stop, which can protect organs from deadly damage.

This is why people can be revived 40 minutes or more after drowning in cold water, or why cooling down the body during surgeries or after heart attacks can be life-saving.

Every muscle in your body relaxes, so you may poop or pee

Within moments of death, the muscles in the body relax, including sphincters that keep what's inside the body from leaking out.

That means, although it can be concerning for families attending the death bed, it's quite natural for some bodies to poop or pee.

A healthcare professional may ask the family to leave the room when that happens so they can clean up the body.

Within hours, blood is pulled downwards, causing splotches on the skin

Because the heart is no longer pumping blood around the body, it starts being pulled down by gravity.

As the blood pools, patches appear on the skin within 30 minutes of death. About two to four hours postmortem, these patches join up, creating large dark purplish areas towards the bottom of the body and lightening the skin elsewhere. This may be less apparent on darker skin.

This process is called livor mortis.

Rigor mortis sets in

Shortly after death, the body is limp and flexible. But as the body breaks down, chemicals like lactic acid — the stuff that causes exercise cramps — and calcium built up in the muscles. This binds muscle cells together and makes the muscles stiffen up, locking them in position.

This process starts in the hands within three to four hours of death, and spreads elsewhere within 12 hours.

Within 36 hours, the muscle cells generally start breaking down and the body goes limp again.

The nails seem to be growing because the skin is shrinking

The hair and nails may look like they are growing after death, but that's a myth.

What's really happening is that the skin becomes drier and more brittle shortly after death. As it shrinks, it makes the nails and hair look longer.

You smell terrible

The body starts breaking down shortly after death, but the physical signs of decomposition only appear later on.

At that stage, the body makes chemicals called putrescine and cadaverine — both of which have foul odors.

Microbes accelerate the decomposition

The chemicals released by the cells as they autolyse send microbes naturally present in your body on a feeding frenzy. The body is usually good at keeping microbes in their place, whether it be the skin, the gut, or any other place that's open to the air.

But as the body has died, bacteria, fungi and other microbes escape their prisons and start growing.

Microbes give your skin a greenish hue

This gives the skin a greenish hue, starting around the belly about 18 hours after death.

Some body parts also start swelling as the microbes let off gas and fluids that pool in the body.

Hair starts falling out

After bloating, the skin starts to become a little more loose.

Black spots appear on the surface, and hair starts falling out. That starts to happen within 24 to 48 hours after death.

Insects come to finish the job

The smell of the body is very attractive to bugs like blow flies and fresh flies, which come to lay eggs in the remains if they are left in the open air.

As the maggots hatch, they munch on any remaining tissue, cleaning the bones. Hair and cartilage can survive this stage of the putrifaction process.

Eventually all that will be left is a pile of bones

In many cases, the body will carry on decomposing until all that is left is the bones. This stage is called skeletonization.

Not all bodies skeletonize. Depending on the conditions, typically in very cold or very hot conditions, some may partially or fully mummify, meaning the skin and maybe some internal tissue will remain preserved.

Every body is different and every one will decompose slightly differently. But ultimately, every body will have to face death at some point or another.