Right-click the picture you want to change. Click Format Picture. In the Format Picture dialog box, click the Picture tab. Under Image control, click Washout in the Color list, and then click Recolor.
There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart.
Since arteries carry oxygen-rich blood away from the heart and veins carry oxygen-depleted blood back to the heart, some people believe that veins appear blue because blood without oxygen is blue. But it's not true! Blood is always red. Oxygen-rich blood is bright red as it leaves the heart.