How do the coronary arteries work?

Carry blood. The coronary afteries are located just above the aortic valve. Blood flows through those arteries and suppies oxygen to the heart muscle. A number of factors can cause the arteries to dilate (become wider) so that the flow of blood can increase if needed such as when you exercise.
Heart function. The heart is a pump made out of a hollow muscle with four chambers, valves, and an electrical conduction system. The coronaries arteries provides nutrients and oxygen to the heart muscle for it to keep pump. When those arteries are blocked the heart muscle can die in a process called heart attack causing the patient to die or causing permanent muscle damage and heart failure.