Why is human blood red?
[ 2006-06-19 14:01 ]
我們的血為什么是紅色的?是什么東西給它染了色?看了下面這篇文章,你就能了解一些了。
 The blood flowing through the
arteries, capillaries, and veins of our bodies contains many different
materials and cells, each with a different function. Plasma, the liquid portion of the blood, comprises
more than half of the blood. Plasma is light yellow in color, and is thicker
than water, because it contains many substances, in addition to the actual blood
cells. These substances include proteins, antibodies that combat disease,
fibrinogen that helps blood
clot, carbohydrates, fats, salts,
and others.
Red blood cells, or corpuscles, encased in blood vessels, color the
blood. Since there are about 35 trillion of these tiny, round, flat discs
circulating in one's body at any one time, their sheer number necessarily lends
their red color to the blood.
As the young red blood cell matures, and
takes on an adult form in the marrow of the bone, it loses its nucleus, and it
increases its production of hemoglobin. Hemoglobin is the red pigment, or
color of blood, and contains iron, combined with protein.
When blood
passes through the lungs, oxygen piggybacks on the hemoglobin of the red cells.
From there, the red cells carry the oxygen through the arteries and the
capillaries to all other cells of the body. Carbon dioxide from the body cells
returns to the lungs through the veins in the same manner, by attaching to the
hemoglobin.
Red blood cells have a life expectancy of approximately four
months, before they are broken up, primarily in the spleen, and are replaced by
new red blood cells. New cells are continuously generated to replace the old
cells that have past their prime, and have been destroyed to make room for the
younger generation.
Let's not forget that, in addition to red blood cells, we
also have several types of white blood cells!
arteries 動(dòng)脈
capillaries 毛細(xì)管
veins 紋理
plasma
血漿
fibrinogen 纖維蛋白原
carbohydrate 碳水化合物
corpuscles
觸覺小體
hemoglobin 血色素
（英語(yǔ)點(diǎn)津Annabel編輯）
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