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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.
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.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
In 1864, the first barbiturate (barbituric acid) was synthesized.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.