This usually begins in the liver, which is enriched in enzymes, and in the brain, which has high water content; eventually, though, all other tissues and organs begin to break down in this way.
Decomposition can divide into five stages – fresh, early decomposition, advanced decomposition, skeletonization, and extreme decomposition. The early decomposition phase begins with the onset of skin slippage and hair loss. These changes usually begin from the first day after death to up to five days post-mortem.
These results provide insight into the observation that the uterus and prostate are the last internal organs to decay during human decomposition.
Once the soft tissues have fully decomposed, all that remains is the skeleton. The skeleton and teeth are much more robust. Although they undergo a number of subtle changes after death, they can remain intact for many years.
NIH states that exposure to elevated temperatures, increased humidity, and/or water can cause accelerated decomposition. A failure to quickly or adequately refrigerate bodies may also lead to early decomposition. The location of the deceased matters greatly when it comes to the rate of decomposition.
A corpse generally progresses through five stages of decomposition—fresh, bloat (autolysis), active decay (putrefaction), advanced decay and skeletonisation.
A larger body mass and more fat will decompose more rapidly. This is because after death, fats will liquify, accounting for a large portion of decomposition. People with a lower fat percentage will decompose more slowly. This includes smaller adults and especially children.
Decompensation progresses over a period of minutes even after the pulse is lost. Even when vascular collapse is the primary event, brain and lung functions stops next. The heart is the last organ to fail.
During cremation, the body parts that do burn consist of organs, soft tissue, hair, and skin, while the water in our bodies evaporates. The body parts that do not burn are bone fragments.
In a temperate climate, it usually requires three weeks to several years for a body to completely decompose into a skeleton, depending on factors such as temperature, humidity, presence of insects, and submergence in a substrate such as water.
The brain and nerve cells require a constant supply of oxygen and will die within a few minutes, once you stop breathing. The next to go will be the heart, followed by the liver, then the kidneys and pancreas, which can last for about an hour. Skin, tendons, heart valves and corneas will still be alive after a day.
The first organ system to “close down” is the digestive system. Digestion is a lot of work! In the last few weeks, there is really no need to process food to build new cells.
This usually begins in the liver, which is rich in enzymes, and in the brain, which has high water content. Eventually, though, all other tissues and organs begin to break down in this way.
And if the body is floating in water less than 70 degrees Fahrenheit (21 degrees Celsius) for about three weeks, the tissues turn into a soapy fatty acid known as "grave wax" that halts bacterial growth. The skin, however, will still blister and turn greenish black.
Putrefaction (4-10 days after death) – Autolysis occurs and gases (odor) and discoloration starts. Black putrefaction (10-20 days after death) – exposed skin turns black, bloating collapses and fluids are released from the body.
Purge fluid is decomposition fluid that may exude from the oral and nasal passages as well as other body cavities (see the image below). Postmortem purge fluid exudes from the oral and nasal passages; no traumatic injuries were uncovered at autopsy.
We think this is an urban legend. We've witnessed many cremations and never heard a scream. But then again, cremation retorts aren't silent either. Now, bodies do make all kinds of gnarly noises.
Does the body feel pain during cremation? The body does not feel pain during cremation because the person is no longer alive. When a person dies, their brain stops sending signals to the body. This means that the person cannot feel pain or any other sensation.
Do teeth burn during cremation? Teeth usually burn up during the cremation process. Tooth fragments that are not burnt up will be ground during the ash processing.
Visions and Hallucinations
Visual or auditory hallucinations are often part of the dying experience. The appearance of family members or loved ones who have died is common. These visions are considered normal. The dying may turn their focus to “another world” and talk to people or see things that others do not see.
Toward the end, you'll remain in this unconscious state of extended rest. Research suggests that even as your body transitions into unconsciousness, it's possible that you'll still be able to feel comforting touches from your loved ones and hear them speaking. Touch and hearing are the last senses to go when we die.
Agonal breathing or agonal gasps are the last reflexes of the dying brain. They are generally viewed as a sign of death, and can happen after the heart has stopped beating.
After two weeks, the body starts to bloat and change its color to red after the blood present in the body starts to decompose. Once the corpse surpasses the fourth week, you can witness liquefaction in the rest of the remains. The teeth and nails also begin to fall during this time frame.
Casket/coffin size
Most caskets are generally a standard size and cannot accommodate a person who is significantly overweight, therefore an “oversize” casket is required. The standard size casket has already increased from 24 inches to 27 inches.
Those who started adulthood as obese and continued to add weight had the highest mortality rate. People who start adulthood with a body mass index (BMI) in the normal range and move later in life to being overweight -- but never obese -- tend to live the longest, a new study suggests.