Compare and contrast the structure and function of arteries, veins and capillaries.

The main coronary arteries branch from the aorta and run along the epicardial surface or the heart. Arterial blood flows from the epicardial arteries inwards towards the endocardial surface. Coronary venous blood returns to the right atrium via the coronary sinus (75%) or via the smaller cardiac veins. Blood vessels flow blood throughout the body. Arteries transport blood away from the heart. Veins return the blood back toward the heart. Capillaries surround body cells and tissues to deliver and absorb oxygen, nutrients, and other substances.