Stages
Five general stages are used to describe the process of decomposition: Fresh, Bloat, Active and Advanced Decay, and Dry/Remains.[3] The general stages of decomposition are coupled with two stages of chemical decomposition: autolysis and putrefaction.[4] These two stages contribute to the chemical process of decomposition, which breaks down the main components of the body
[edit] Fresh
The fresh stage begins immediately after the heart stops beating.[5] Since blood is no longer being pumped through the body it drains to the dependent portions of the body, under gravity, creating an overall bluish-purple discolouration termed livor mortis or, more commonly, lividity. Shortly after death, within three to six hours, the muscular tissues become rigid and incapable of relaxing which is known as rigor mortis. From the moment of death, the body begins losing heat to the surrounding environment, resulting in an overall cooling called algor mortis.[6]
Once the heart stops, chemical changes occur within the body and result in changes in pH, causing cells to lose their structural integrity. The loss of cell structure brings about the release of cellular enzymes capable of initiating the breakdown of surrounding cells and tissues. This process is known as autolysis. Visible changes caused by decomposition are limited during the fresh stage, although autolysis may cause blisters to appear at the surface of the skin.[7]