Hear an exposed human heart beating

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Worried about diphtheria? No? Thank vaccines.

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Learn about the chemical process the human body uses to digest carbohydrates, proteins, and fats.

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Glyphosate is highly effective at managing weeds—but is that all it does?

Media Editor: Casey Mendoza

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In a circuit through the cardiovascular system, red blood cells transport oxygen from the lungs to the body tissues and carry carbon dioxide from the body tissues back to the lungs.

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The vascular system is a network of arteries, veins, and capillaries that supplies blood to the tissues of the body.

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Bright swarms of Daphnia serve as the food source of many larger animals. The internal processes of Daphnia are easily studied through its transparent carapace. A single eye, sensitive to light, causes Daphnia to react in a sunlit river.

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Every minute, multiple liters of air are cycled through your lungs.