When a coronary artery narrows or closes, the area of the heart through which the artery is lubricated becomes ischemic and damaged, and a heart attack may occur. Oxygen is directly related to heart activity. The more active the heart, the greater the need for oxygen, and the coronary artery blood flow is adjusted according to the heart muscle's need for oxygen. The heart muscle consumes about 65% of the oxygen in the coronary artery, while other tissues in the body consume a maximum of 25% of the oxygen in the blood of the coronary artery. Also, unlike other tissues in the body, 75% of the heart muscle blood is supplied at rest by diastole of the heart. The coronary arteries are responsible for supplying blood to the heart muscle. The right and left coronary arteries branch from the aorta just above the aortic valve, then enter the heart and supply blood to the capillaries of the heart muscle. The two grooves meet at the posterior region of the heart in a place called the CRUX, where the AV group is located. If the RCA supplies blood to the cortex, these people are called the dominant right. The descending RCA branch intoxicates the left posterior muscle. Approximately 18% of people with CCA and RCA donate blood to the heart crocus, in which case it is called a balanced arterial pattern.