A B-double or consists of a prime mover towing two semi-trailers, where the first semi-trailer is connected to the prime mover by a fifth wheel coupling (aka 'converter dolly') and the second semi-trailer is connected to the first semi-trailer by a fifth wheel coupling.
1 Arteries. 2  Arteries are elastic vessels that transport blood away from the heart. 3  Pulmonary arteries carry blood from the heart to the lungs where oxygen is picked up by red blood cells. 4  Systemic arteries deliver blood to the rest of the body. 5  Veins. 6  Veins are elastic vessels that transport blood to the heart.
Arteries are muscular blood vessels that carry blood away from the heart, oxygenated and deoxygenated blood. The pulmonary arteries will carry deoxygenated blood to the lungs and the sytemic arteries will carry oxygenated blood to the rest of the body.