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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
The most dangerous mercury compound, dimethyl mercury, is so toxic that even a few microliters spilled on the skin can cause death. Mercury has been shown to accumulate in higher amounts in the following types of fish than other types: swordfish, shark, mackerel, tilefish, crab, and tuna.
There are more sensory neurons in the tongue than in any other part of the body.
To maintain good kidney function, you should drink at least 3 quarts of water daily. Water dilutes urine and helps prevent concentrations of salts and minerals that can lead to kidney stone formation. Chronic dehydration is a major contributor to the development of kidney stones.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
![Positron emission tomography (PET) image showing the difference in the metabolic activity of the bra](https://biology-forums.com/gallery/47/medium_14755_27_08_12_12_14_19_81821620.jpeg)
![An example of color blindness test. A person with red-green color blindness would not be able to dis](https://biology-forums.com/gallery/47/medium_14755_27_08_12_12_28_10_82021889.jpeg)