Structure of the Coronary Arteries
Like other arteries in the body, the coronary arteries have three layers: the inner layer (intima), the muscular layer (media), and the outer layer (adventitia). The inner surface of the blood vessel is lined by a layer of cells called the endothelium. The cavity (channel) within the vessel in which blood flows is called the lumen.
Common reasons why your heart may demand more oxygen
Fast heart rate due to exercise, excitement, or heart rhythm abnormality
Strong contractions of the heart due to exercise
High pressure inside the heart chambers, especially the ventricles, due to high blood pressure or valve problems
Enlarged heart chamber due to any condition that causes heart failure
Increased muscle mass (thickening of the heart muscle) due to heart muscle abnormalities, high blood pressure, or valve problems