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There are more bacteria in your mouth than there are people in the world.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
Asthma cases in Americans are about 75% higher today than they were in 1980.
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.
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.