CORONARY ARTERIES AND HEART VALVES
Coronary Arteries
  • A normal heart is about the size of your clenched fist and is positioned in your chest slightly to the left of your breastbone (sternum). It is made of muscle and continuously pumps blood rich in oxygen and nutrients, around the body
  • The heart itself requires oxygen and nutrients so that it can carry out its pumping action
  • Coronary arteries supply blood that contains oxygen to the heart
  • A large artery called the aorta carries oxygen rich blood from the heart to the rest of your body
  • The coronary arteries branch off the aorta
  • There are two coronary arteries, which originate from the aorta to supply the heart with oxygen-rich blood
  • The right coronary artery divides into two main branches: the posterior descending  artery, and the marginal artery
  • The left coronary artery also divides into two main branches: the anterior descending artery and the circumflex artery
  • These coronary arteries form a network over and through every part of the heart
  • This enables every part of the heart to be nourished with oxygen and nutrients
When the blood supply to the heart muscle is not sufficient to provide enough oxygen for the heart, pain, called angina, occurs.

The pain can occur after exertion (physical exercise or hard work) or at rest.
Heart valves
  • Valves are essential to your heart’s pumping function. Your heart has four valves, or tissue flaps, that open and close, allowing blood to flow in one direction. At the entrance and the exit of each ventricle there is a valve.
  • The valves at the entrance of the ventricles only allow blood in and the valves at the exit only allow blood out.
  • There are 4 valves in the heart:
    • Tricuspid valve, which lies between the right atrium and right ventricle
    • Pulmonary (pulmonic) valve, between the right ventricle and the pulmonary artery
    • Mitral valve between the left atrium and the left ventricle
    • Aortic valve between the left ventricle and the aorta
Each valve has a set of "flaps" (also called leaflets or cusps). The mitral valve has two flaps; the others have three.

Oxygen poor blood returns to the heart after circulating through the body. It flows through the veins and enters the right atrium. This chamber empties blood through the tricuspid valve into the right ventricle. The right ventricle pumps blood under low pressure through the pulmonary valve into the pulmonary artery. From there the blood goes to the lungs, where it gets fresh oxygen. Oxygen-rich blood then returns to the left atrium. From there it passes through the mitral valve and enters the left ventricle.
 
The left ventricle pumps this oxygen-rich blood through the aortic valve and into a large artery called the aorta. The aorta takes blood from the heart to the rest of the body. The pressure in the left ventricle is a high pressure similar to the blood pressure measured in the arm. When passing through the body, oxygen in the blood is distributed to the tissues. The cycle continuously repeats as the blood flows back to the heart.