Species range in size from the hefty Common Raven (Corvus corax), at 1.5 kg (3 lb 5 oz) and 70 cm (2 ft 3 in), to the diminutive Short-tailed Pygmy Tyrant (Myiornis ecaudatus), at just 4.2 g (0.14 oz) and 6.5 cm (2 Â½ in).
The heart receives its own supply of blood from the coronary arteries. Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet. These arteries and their branches supply all parts of the heart muscle with blood.hen the coronary arteries narrow to the point that blood flow to the heart muscle is limited (coronary artery disease), collateral vessels may enlarge and become active.
An artery is an elastic blood vessel that transports blood away from the heart. There are two main types of arteries: pulmonary arteries and systemic arteries.Pulmonary arteries carry blood from the heart to the lungs where the blood picks up oxygen.The oxygen rich blood is then returned to the heart via the pulmonary veins. Systemic arteries deliver blood to the rest of the body. The aorta is the main systemic artery and the largest artery of the body.It originates from the heart and branches out into smaller arteries which supply blood to the head region (brachiocephalic artery), the heart itself (coronary arteries), and the lower regions of the body.ulmonary arteries carry blood from the heart to the lungs where the blood picks up oxygen. The oxygen rich blood is then returned to the heart via the pulmonary veins. Systemic arteries deliver blood to the rest of the body.