If energy can only be transformed and not made, what happens to the energy in a person when that person dies?
Holly Cobb from Kent (age 5-14)
Filed under: age 5-14, Answered Big Questions, Death Big Questions, Energy Big Questions, Eram Rizvi's Big Answers, Particle Physics Big Questions, Physics Big Questions, Tim Dawson's Big Answers
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ATP (Adenosine Tri-Phosphate) is the most readily available form of energy substrate in cells. When we are alive our cells are constantly regenerating this substance from ADP (Di-Phosphate) using glucose and oxygen and producing carbon dioxide and water. When we die (heart beat and breathing stop) our cells continue for a short time to use up stocks of glucose and oxygen and utilise ATP for cell processes before the chemical reaction slows and ceases – maybe several hours after the heart stops, depending on ambient temperature.
One of these processes keeps muscle fibres sliding over each other. When all the ATP is used up the muscles of a dead person become “stiff”, which is known as Rigor Mortis.
ATP also keeps potent digestive enzymes in the cells locked up. When the ATP is used up these enzymes break out and start digesting the body cells from inside – a process known as Putrifaction.
After death the protective mechanisms that keep bacteria at bay in the gut is lost and these invade tissues and begin to breakdown fats, proteins etc. using up the energy locked up in them. So everything is eventually recycled.
Tim Dawson
Consultant and Senior Lecturer in Neuropathology
Fellow of the Royal College of Pathologists
The Royal College of Pathologists is holding an event entitled, Sex Drugs and Alcohol during National Science and Engineering Week. Our first National Pathology Week (3 – 9 November 2008) is taking place this year. See http://www.rcpath.org/index.asp?PageID=1526 for more details.
Hello Holly,
Tim has given us a very detailed answer, but I’m going to try and say the same thing a little more simply.
The energy that we have when we are alive is all in the form of chemical energy – a bit like a battery. Some of it is also in the form of heat energy, but this is quickly lost when we die as our body cools down.
When we die most of that energy will remain as chemical energy of one sort or another as bacteria start to use our bodies as food. If the body is buried, then this chemical energy will go to powering the organisms that feed on the body. On the other hand, if the body is cremated then the chemical energy is turned into heat energy of the hot gases that escape the cremation chamber.