Blood is a fluid substance that circulates in the arteries and veins of the body. Blood is bright red or scarlet when it has been oxygenated in the lungs and passes into the arteries; it becomes bluish red when it has given up its oxygen to nourish the tissues of the body and is returning to the lungs through the veins and the tiny vessels called capillaries. In the lungs, the blood gives up the …showed first 75 words of 1395 total…

…showed last 75 words of 1395 total…