Image: David Gregory & Debbie Marshall, Wellcome Images This is what a colour-enhanced image of the inner surface of your lung looks like. The hollow cavities are alveoli; this is where gas exchange occurs with the blood.
I've seen the RBC morphology of this so far as an MT. Twice the presentation was overt. The other time was not as apparent. This was one instance where info on the person's race/ethnicity played a role in sending out for confirmation.