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.
A blood vessel's main function is to transport blood around the body. Blood vessels also play a role in controlling your blood pressure. Blood vessels are found throughout the body. There are five main types of blood vessels: arteries, arterioles, capillaries, venules and veins.Arteries carry blood away from the heart to other organs.lood vessels also play a role in controlling your blood pressure. Blood vessels are found throughout the body. There are five main types of blood vessels: arteries, arterioles, capillaries, venules and veins. Arteries carry blood away from the heart to other organs.