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53

You must tell facts from fiction; viruses need living cells to replicate, because they do not have the molecular machinery at hand to generate energy and construct building blocks essential to life. So no, viruses cannot bring back the dead or revitalize dead cells. The thing that comes close to it are zombie ants. These ants have been infected by a ...


8

Note: This answer is a complement to @Christiaan's answer, and is partly reusing stuff from this related answer. Since you are specifically asking about viruses, I thought that it might be interesting to mention that similar behaviour changes as those mentioned for fungi can also be caused by viruses. See e.g. this quote from Roy et al. (2006): In ...


7

I don't exactly know what you meant to say by "non-functional". Red blood cells are delivering oxygen to tissues, but they cannot do this anymore in the lack of blood flow. White blood cells degenerate and after about 84 hours are no longer existing as cells (Babapulle CJ, Jayasundera NP, 1993). Neutrophiles degenerate first and lymphocytes last. Platelets ...


6

Yes. Moreover, even if they were not urinating at the time of death, they likely would at death, assuming adequate filling of the urinary bladder. There are two sphincters that close off the urethra. One is under control of the autonomic nervous system and the other is voluntarily controlled (somatic). At death, both sphincters will relax, releasing the ...


6

Second law of thermodynamic and ageing The second law of thermodynamic applies to closed system. Organisms are not closed system. The second law of thermodynamic is a fundamental principle of our universe and any biological processes do follow the principles of physics. However, stating that biological ageing is (partially) caused by the second law of ...


5

A good working theory is that this is caused by Rigor Mortis and the anatomy of insect legs. In most cases, the muscles that pull the leg down (or closer together) are larger than the ones that pull the leg up. This is because those muscles (flexors) must support the insect's weight: (Click for larger view) When the muscles contract after death, the ...


4

One difference between living and dead tissue, but specific to muscles is tonus. In living skeletal muscle, random nerve impulses fire to keep muscles in a partially contracted, ready-to-use state. Without this low-level tension sarcomeres, the basic units of skeletal muscle, would not recover from being poked and could more easily be pulled out of optimal ...


4

Capillary refill time is defined as the time taken for the capillaries to refill after the blood in them has been squeezed out by pressure. It is widely used as a quick way to determine the effectiveness of the circulatory system in humans by doctors. In a normal living organism, the capillaries will take time to refill after they have been emptied. Muscle ...


4

Your question is a little vague and as Christiaan mentioned, linking to the papers would be useful. If I understand, though, you want to know why cellular metabolic activity that takes places after someone dies? If that's the case, the answer is essentially that whatever kills a complex organism in the sense of causing the heart to cease beating, doesn't ...


3

The LD 50 listed on the wikipedia page you link to is 90 mL/kg, which would be about 6 liters for a 68 kg (150 lb) person. This is consistent with at least one report, where someone died from drinking 7 liters of water in 1.5 hours. The mechanism by which water kills people is by lowering the amount of ions (chiefly sodium) in the blood. A condition called ...


3

There are species where cells and even whole organisms can go into a state called cryptobiosis where their metabolism is suspended but can be revived later. This usually happens when the conditions become too bad for survival (dry/cold etc.) and is reversed once the conditions improve again (rehydration warming up). One prominent and fascinating example are ...


3

The terrestrial invertebrate taxon advisory group of the Association of Zoos and Aquariums recommends anesthetizing the insects with carbon dioxide and then placing them in a freezer to euthanize them.


2

We human are scare of death. Because of that, we tend to apply that idea into everything we can observe, even if it's meaningless. But why is death scary? Isn't it because when you die, you stop function anymore? Fear of death is hard-wired into our nervous systems. A thirsty wildebeest will approach crocodile-infested water very, very reluctantly. The ...


2

What is the longest observed lifespan of a mosquito, especially of the species Anopheles arabiensis? Mean lifespan calculations for Anopheles arabiensis range from 14 days (Karoki, 2013)* to 21 days (Yamada et al. 2014)** *This Masters thesis tests efficacy of different drugs against An. arabiensis, 14 days is the mean control lifespan. **These An. ...


2

The WHO has data from 2002 where they have classified and counted causes of death. I have treated the following as natural causes: Cardiovascular disease (29.34%) Infectious & Parasitic disease (23.04%) Cancers (12.49%) Respiratory disease (6.49%) Perinatal conditions (4.32%) Digestive disease (3.45%) Neuropsychiatric disorders (1.95%) Diabetes (1.73%) ...


1

Stretching the limits of what is known a bit, there is an interesting example of a phage (virus that infects bacteria) infecting a photosynthetic bacterium in the ocean that deserves mentioning. What is amazing here is that the phage has certain genes that are required for photosynthesis within its genome. Why does it have these? The phage extends the ...


1

Check out the sources of Wikipedia article: the mortality rate is up to 4%. The main causes of "immediate" death in penetrating trauma are shock (low blood pressure due to external/internal hemorrhage, especially arterial hemorrhage), pneumothorax, penetrating heart injury (with resultant hemopericardium) and other less frequent causes. The same causes ...



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