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Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
An identified risk factor for osteoporosis is the intake of excessive amounts of vitamin A. Dietary intake of approximately double the recommended daily amount of vitamin A, by women, has been shown to reduce bone mineral density and increase the chances for hip fractures compared with women who consumed the recommended daily amount (or less) of vitamin A.
To prove that stomach ulcers were caused by bacteria and not by stress, a researcher consumed an entire laboratory beaker full of bacterial culture. After this, he did indeed develop stomach ulcers, and won the Nobel Prize for his discovery.
![The pancreas. This organ sits just below the stomach and is both an exocrine and an endocrine gland.](https://biology-forums.com/gallery/47/medium_14755_28_08_12_1_42_25_8233102.jpeg)
![Herniated disk. A herniated disk is a protrusion of the disk’s gelatinous center, called the nucleus](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_28_47_10077486.jpeg)
![In this painting evangelist George Whitefield appears to be cross-eyed. This is no fault of John Wol](https://biology-forums.com/gallery/47/medium_374628_15_08_15_11_50_50_222292090.jpeg)