Question

Bird respiration

Beginning with inhalation describe the pathway an oxygen molecule would go until the molecule is absorbed in the bloodstream in a bird. Be sure to include where an oxygen molecule would go if it is not absorbed.

Answer 1

During inspiration, the inhaled air pass through the nostrils or nares at the junction at beak and head. From there it enters into trachea through larynx. Air then moves into the syrinx. As the trachea divides here,the air stream is also divided.The air now passes to the posterior air sacs.Little amount of air will move to the lung through caudal sacs.

At first expiration, from posterior air sacs,the air moves into lungs through the ventrobronchi and dorsobronchi. These bronchi further divide into air capillaries which are very small in diameter. Blood vessels flow through the air vessels and here, the oxygen and carbon dioxide exchange occurs.The air moves to the cranial air sacs when there is second inspiration by the bird.With the second expiration, air travels out of the cranial air sacs,by the syrinx into the trachea, through the larynx, and lastly through the nasal cavity and passes out of the nostrils.