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When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
Many of the drugs used by neuroscientists are derived from toxic plants and venomous animals (such as snakes, spiders, snails, and puffer fish).
Signs and symptoms of a drug overdose include losing consciousness, fever or sweating, breathing problems, abnormal pulse, and changes in skin color.
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.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.