Explanation:
When the amount of oxygen in the blood decreases, the skin and mucous membranes can turn a bluish color, a condition known as cyanosis. This happens because the red blood cells contain less oxygen, and the blood takes on a darker, bluer shade. Cyanosis is often seen in the lips, fingertips, and toes. It is a sign that the blood isn't carrying enough oxygen, which can happen due to various medical conditions like respiratory issues or heart problems. Cyanosis is different from jaundice, paleness, or flushing, which are caused by other factors.