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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.
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 term bacteria was devised in the 19th century by German biologist Ferdinand Cohn. He based it on the Greek word "bakterion" meaning a small rod or staff. Cohn is considered to be the father of modern bacteriology.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
Many people have small pouches in their colons that bulge outward through weak spots. Each pouch is called a diverticulum. About 10% of Americans older than age 40 years have diverticulosis, which, when the pouches become infected or inflamed, is called diverticulitis. The main cause of diverticular disease is a low-fiber diet.
![Open-top chambers, such as the one pictured above in a polar desert on Ellesmere Island, are commonl](https://biology-forums.com/gallery/47/medium_33_17_02_12_7_03_54_2045199.jpeg)
![The Pleiades, an open cluster of stars in the constellation of Taurus. These stars share a common mo](https://biology-forums.com/gallery/47/medium_12359_26_01_13_3_54_20.jpeg)