Why do the lungs clear ultrasonic contrast?
D002196:Capillaries / Q000378:metabolism; D003287:Contrast Media / Q000378:metabolism*; D004452:Echocardiography; D006801:Humans; D008168:Lung / Q000098:blood supply / Q000378:metabolism*; D008954:Models, Biological; D009584:Nitrogen; D013499:Surface Properties; D013500:Surface Tension
D003287:Contrast Media; D009584:Nitrogen