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. Arteries have a thick wall that consists of three layers.