Naked Science Forum
General Science => General Science => Topic started by: bizerl on 07/01/2013 00:17:41
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After being immersed in the world of "The Walking Dead" (http://www.amctv.com/shows/the-walking-dead), a zombie show where a disease is re-igniting the brain stems of the people it kills, turning them into a rotting corpse that can walk around, bite people and infect them with the disease, I've had zombies on the brain.
Anyway, it made me wonder just what it is about being "alive" that stops our flesh from decaying (or any flesh for that matter).
Any thoughts from those big juicy, succulent brains out there?
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Bacterial infection is wot causes rot ...
http://www.kscience.co.uk/revision/B2_revision_exe/how_do_our_bodies_resist_infection.html
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Our cells are living things. They stay alive providing they maintain a supply of oxygen to release energy from molecules like glucose, and a means of getting rid of waste products. But if you cut off the blood supply and oxygen to a body part, that tissue will start to die and deteriorate. Cells can also divide and replace themselves if the are damaged, or are replaced with scar tissue.
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Simply - blood flow - as long as oxygenated blood is reaching them cells will not rot except in some very unusual cases - although when necrosis (cell death) has started the byproducts of it can rapidly poison otherwise healthy tissue.
If deprived of oxygen ( ischemia ) cells start to die and then start breaking down fairly quickly. For example a blood clot causing a stroke (Transitory Ischemic Attack) can result in brain damage due to oxygen depreivation to brain cells. Another example is where a limb is crushed such as by a boulder. If this cannot be removed very quickly (within about 1/4 hour) the reuslting breakdown of cells releases toxins into the blood, which when the limb is released can flood back into the body and if not properly treated on scene are likely to be fatal
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Rotting, of course, is the invasion of tissue with micro-organisms (bacteria).
Your body has various antibodies, as well as B cells, T cells, and macrophages to keep the bacteria from invading. On the outside of the body, the skin provides an effective barrier against invasion.
If the body dies, or the blood stops circulating, then these cellular protective mechanisms also stop functioning, allowing the bacteria to attack.
Gangrene (http://en.wikipedia.org/wiki/Gangrene) can be a dangerous situation caused by poor circulation in certain body parts leading to necrosis of the affected areas, while at least initially the rest of the body remains alive.