Images taken from following website! http://people.eku.edu/ritchisong/birdrespiration.html Lungs and air sacs in birds

1. 

3. Represented By
Mr. Vaibhav Kisan Phadtare.
Roll No.: 630
T.Y.B.Sc Zoology
Yashvantrao Chavan Institute of Science, Satara Dist-
Satara- 415002.

4.  Soft, Spongy, right lung has 3 lobes, left lung has 2
lobes.
 Occupy the pleural cavities.
 Made of elastic tissue that stretches an recoils as we
breathe.
 Tissue must be moist to allow gas exchange.
 Bird lungs do not expand or contract like the lungs of
mammals

6.  Air sacs are thin walled structure.
 Extended into the body cavity and into the wing and
leg bones.
 Most birds have 9 air sacs
 One interclavicular sac
 Two cervical sacs
 Two anterior thoracic sacs
 Two posterior thoracic sacs
 Two abdominal sacs

7.  Functionally, these 9 air sacs can be divided into
anterior sacs (interclavicular, cervicals, & anterior
thoracics) & posterior sacs (posterior thoracics &
abdominals).
 As we know, air sacs have very thin walls with few
blood vessels. So, they do not play a direct role in gas
exchange. Rather, they act as a 'bellows' to ventilate the
lungs .

8.  Air flow through the avian respiratory system during
inspiration (a) and expiration (b).
1. Interclavicular air sac
2. Cranial thoracic air sac
3. Caudal thoracic air sac
4. Abdominal air sac

10.  Unidirectional flow of air .
 Delivers huge quantity of O2.
 Remove lethal body heat.
 Protect internal delicate organs.
 Interclavicular sac is essential for vocal sound
production.