The coronary arteries supply the blood to the tissues of the heart, which is made up of cells called myocytes. In the body, the heart acts like a pump and contracts in order to force blood out into the rest of the body- in order to contract the heart needs energy. The coronary arteries supply the heart with oxygen and with nutrients in order for respiration to take place. Through the process of repsiration (glycolysis, Krebs cycle and electron transport chain) ATP is created and ATP is a form of energy which is essential in muscle contraction- especially in the heart.