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Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
There are 60,000 miles of blood vessels in every adult human.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
Pink eye is a term that refers to conjunctivitis, which is inflammation of the thin, clear membrane (conjunctiva) over the white part of the eye (sclera). It may be triggered by a virus, bacteria, or foreign body in the eye. Antibiotic eye drops alleviate bacterial conjunctivitis, and antihistamine allergy pills or eye drops help control allergic conjunctivitis symptoms.
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.