9.3 Blood vessels

The three blood vessel types — arteries (thick wall, narrow lumen, high pressure, away from heart), veins (thin wall, wide lumen, valves, low pressure, back to heart) and capillaries (1 cell thick, exchange site). Named vessels of the heart (aorta, vena cava), lungs (pulmonary artery + vein), kidneys (renal artery + vein) and (HL) liver (hepatic artery, hepatic vein, hepatic portal vein). HL extends to explaining how each structure matches its pressure or exchange function.