In mammals, air enters lungs through tubes called which branch into smaller tubules called which extend out to tiny air sacs called

 In mammals, air enters lungs through tubes called , which branch into smaller tubules called , which extend out to tiny air sacs called . 
trachea; bronchioles; spongy tissue 
>> bronchi; bronchioles; alveoli 
bronchi; alveoli; gills 

This type of galaxy is an approximately ellipsoidal shape and a smooth, nearly featureless image. they are the largest single star systems, in the universe and are built by the collisions of many smaller galaxies.

The anwser is the universe