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The familiar sounds of your heart are made by the heart's valves as they open and close.
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.
On average, the stomach produces 2 L of hydrochloric acid per day.
Certain chemicals, after ingestion, can be converted by the body into cyanide. Most of these chemicals have been removed from the market, but some old nail polish remover, solvents, and plastics manufacturing solutions can contain these substances.
Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.