Term
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Definition
| There must be an irreversible halt of circulatory and respiratory systems, as well as an irreversible halt of all brain and brain stem function. |
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Term
| What is associated with being "brain dead?" |
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Definition
| Comas, cerebral unresponsiveness, apnea, dilated pupils, lack of brain stem reflexes, and lack of electrocerebral activity. |
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Term
| Initial Post-Mortem Changes |
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Definition
| Bodily functions stop, so the body begins to break down. Circulation and digestion stop, the chemical composition of body fluids changes, the normal flora of the gut take over, and animals feed on the body (when applicable). |
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Term
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Definition
| The body cools to ambient temperatures (1.5-2 F per minute). |
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Term
| What part of the body cools the fastest? |
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Definition
| The skin. It is not used to determine body temperature. The core is used for the measurements, so temperature is sometimes taken from the rectum, liver, or brain. |
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Term
| What can influence the rate of cooling? |
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Definition
| Clothing on the body, the amount of body fat, any air currents, immersion in water, and size of the body. |
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Term
| What part of the body demonstrates the earliest post-mortem changes? |
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Definition
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Term
| What happens to the eyes post-mortem? |
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Definition
| Red blood cells settle in the capillaries, a thin film on the corena forms within 2-3 minutes, and cloudiness in the cornea begins within 2-3 hours. Eyes that are open develop black spots. In about 4 days, the intraocular fluid dries out. Potassium diffuses out. |
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Term
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Definition
| One of the most important post-mortem signs. It is the occurence of black spots developing in open eyes. |
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Term
| Why does potassium diffuse out of the eye? |
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Definition
| The sodium-potassium pump maintains a higher level of potassium in the eye as compared to the blood in a living person. When the pump runs out of ATP, the potassium diffuses out. |
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Term
| How is the diffusion of potassium from the eye used to determine a time of death? |
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Definition
| 7.14 x [K+] - 39.1 = hours since death |
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Term
| What happens to digestion post-mortem? |
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Definition
| Digestion stops. The stomach empties out at a known rate, solids being slower than liquids. Starchy and fatty foods move more slowly, too. Digestive juices start to eat away at the organs, including the pancreas, stomach, and liver. |
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Term
| What are some rates of stomach-emptying post-mortem? |
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Definition
| Light meals take 1.5-2 hours. Heavy meals take 3-4 hours. Liquids take .5 hours. |
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Term
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Definition
| Purple-blue-reddish discoloration caused by the settling / pooling of the blood in capillaries due to gravity. |
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Term
| How is livor mortis used to calculate time of death? |
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Definition
| It can be seen as early as 20 minutes and becomes "fixed" in 8 - 12 hours. |
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Term
| What does red blood cell hemolyse do post-mortem? |
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Definition
| It causes pigment to diffuse into surrounding tissue. Later, it becomes metabolized to sulphemaglobin, resulting in a greenish color. |
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Term
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Definition
| Results in a purple-reddish / purple skin discoloration. |
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Term
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Definition
| At first, after death the body's muscles are flaccid. Later, muscle fibers bind together because the energy required to relax the fibers has depleted. |
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Term
| How is rigor mortis used to estimate the time of death? |
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Definition
| It takes 12 hours for it to appear and it lasts for another 12 hours, so it takes another 12 hours for it to disappear. |
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Term
| What can have an effect on rigor mortis? |
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Definition
| If a death was preceeded by extreme excitement or tension (drownings, murders), it is possible for rigor mortis to occur without the initial flaccidity. Previous exercise, heat, electrocution, or convlusions can also have an effect. |
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Term
| Physiology of Rigor Mortis |
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Definition
| There is an increase in intracellular Ca2+ due to leaky membranes of the sarcoplasmic reticulum and cell. It causes torpinin and tropomyosin to move aside, allowing actin and myosin to bind. This forms cross-bridges using the remaining ATP. None is left to break the bridges. Eventually, the cross-bridges break as proteins degrade. |
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Term
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Definition
| Includes the production of gases, such as methane, CO2, hydrogen, and amonia. it is the early stage of decomposition. |
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Term
| What does putrefaction tell us about the time of death? |
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Definition
| It sets in after 24-30 hours, causing a greenish discoloration in the abdomen. |
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Term
| What affects putrefaction? |
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Definition
| The temperature, prior health, and the environment - air has a faster decomposition (1 week), followed by water (2 weeks), and then soil (8 weeks). |
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Term
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Definition
| Dark discoloration of the face and fluids from the nose and mouth. Body thickens because of the release of gases within it. |
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Term
| What two stages are linked to eachother? |
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Definition
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Term
| How long does bloat take to set in? |
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Definition
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Term
| What causes mummification? |
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Definition
| Dry environments prevent tissues from decomposing as readily. |
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Term
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Definition
| Leathery skin with a shrunken and dark body. The body can last this way for a very long time. |
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Term
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Definition
| High humidity / temperature. |
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Term
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Definition
| Breakdown of body lipids by autolysis and bacterial decomposition. It results in a lowering of the pH in the body, reducing microbial activity. It is connected with a characteristic odor. |
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Term
| Why is adipocere known as "grave wax?" |
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Definition
| The body lipids turn into a clay-like, gray substance. |
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Term
| How does bacteria contribute to adipocere? |
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Definition
| Bacterial enzymes convert unsaturated fats into saturated, solid fats. |
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Term
| How is adipocere used to determine time of death? |
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Definition
| It takes 3-6 months to develop |
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Term
| Skeletonized / Putrid Dry Remains |
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Definition
| Loss / removal of all soft tissue - only skeleton remains. Note: catilege is slower at decomposing than other tissues, so the bones might still be held together. |
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Term
| What affects skeletonization / how is it used to determine time of death? |
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Definition
| Climate: temperate regions = 1.5 years, hot and humid regions = 10 days. |
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