Ospreys like humans use their nostrils or nares to inhale oxygen. Air is moved in and out of the respiratory system through pressure changes accruing in their air sacs. Since ospreys do not have diaphragms they need other ways to exhale in order to get fresh air. Using Muscles in their chests, the sternum is pushed outward. Doing this makes negative pressure in the air sacs, causing oxygen to enter the respiratory system. "Expiration is not passive, but requires certain muscles to contract to increase the pressure on the air sacs and push the air out." {1} The lungs of an osprey do not expand and contract like the lungs of humans. When Ospreys breathe they transfer more oxygen with each breath then humans. Since air is transferred faster so are toxins found in the what they are breathing in. "Respiration in birds requires two respiratory cycles (inspiration, expiration, inspiration, expiration) to move the air through the entire respiratory system."{1} Air moves through the nostrils into the nasal cavity then into the trachea. From the trachea it moves to the syrinx. the syrinx is found in birds, it divides the incoming air into two sections.The air does not go directly to the lung, but instead travels to the caudal (posterior) air sacs. A small amount of air will pass through the caudal air sacs to the lung. "During the first expiration, the air is moved from the posterior air sacs through the ventrobronchi and dorsobronchi into the lungs. The bronchi continue to divide into smaller diameter air capillaries."{1} Like humans, Ospreys under go cellular resportation. Using ATP, or braking of phosphate bonds to create energy. In order to make the food they ingest into energy, Ospreys must burn glucose in their mitochondria. {1}http://www.mytoos.com/airsacs.html