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Q. Describe the double circulation in human beings.

During a single cycle blood goes twice in the heart which is known as double circulation. It is necessary in human being to separate oxygenated and de-oxygenated blood because this makes their circulatory system more efficient and helps in maintaining constant body temperature.  During a single cycle, the blood goes twice in the heart. This double circulatory system is important because it ensures provision of oxygenated blood to the muscle and not a mixture of oxygenated and de-oxygenated blood. Hence, this system ensures efficient supply of oxygenated blood to the muscles.

Explanation:

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answer; i believe its echoic memory,it is believed to last three to four seconds; good luck

it would lead to upper respiratory infections and pneumonia.