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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.
The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.
Blood is approximately twice as thick as water because of the cells and other components found in it.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
It is difficult to obtain enough calcium without consuming milk or other dairy foods.
![Surface magnetic field of SU Aur (a young star of T Tauri type), reconstructed by means of Zeeman-Do](https://biology-forums.com/gallery/47/medium_12359_16_06_12_7_20_16.jpeg)
![The cardiovascular system. A schematic view of the closed circulation of blood. The heart is section](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_14_25_100191159.jpeg)