Coronary arteries - image description

The illustration shows two tubes. These are two blood vessels or arteries. The arteries are shown in cross section. An arrow shows how blood flows through each vessel. In one artery, the arrow is large to show that the blood flows easily along the blood vessel. This is labelled normal blood flow. In the other artery, there is an area of fatty tissue attached to the inside of the artery wall. This makes the inside of the artery much narrower. The arrow becomes small and thin to fit past the fatty tissue. It is labelled abnormal blood flow.