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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.
Looking at the sun may not only cause headache and distort your vision temporarily, but it can also cause permanent eye damage. Any exposure to sunlight adds to the cumulative effects of ultraviolet (UV) radiation on your eyes. UV exposure has been linked to eye disorders such as macular degeneration, solar retinitis, and corneal dystrophies.
It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.
According to the National Institute of Environmental Health Sciences, lung disease is the third leading killer in the United States, responsible for one in seven deaths. It is the leading cause of death among infants under the age of one year.
More than nineteen million Americans carry the factor V gene that causes blood clots, pulmonary embolism, and heart disease.