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  3. Blood is vital to maintaining a stable body temperature; in humans, body temperature normally fluctuates within a degree of 37.0

Blood is vital to maintaining a stable body temperature; in humans, body temperature normally fluctuates within a degree of 37.0

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问题     Blood is vital to maintaining a stable body temperature; in humans, body temperature normally fluctuates within a degree of 37.0℃. Heat production and heat【B1】______in various parts of the body are balanced out by heat transfer【B2】______tile bloodstream. This is accomplished by varying the【B3】______of blood vessels in the skin. When a person becomes【B4】______, the vessels dilate(膨胀)and an increased volume of blood flows through the skin. Heat dissipates(消散)through the skin, effectively【B5】______the body temperature. The increased flow of blood in the skin makes the skin appear【B6】______or flushed. When a person is cold, the skin may become pale as the【B7】______narrow, diverting blood from the skin and reducing heat loss.
    About 55 percent of the blood is【B8】______of a liquid known as plasma(血浆).【B9】______: red blood cells, white blood cells, and platelets.
    Blood, vital fluid found in humans and other animals that provides important nourishment to all body organs and tissues and carries away waste materials. Sometimes referred to as "the river of life,"【B10】______
    An adult human has about 5 to 6 liters of blood, which is roughly 7 to 8 percent of total body weight.【B11】______.The volume of blood in an individual fluctuates.
【B11】
选项
答案Infants and children have comparably lower volumes of blood, roughly proportion- ate to their smaller size
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