The respiratory system: Comparing the lung structure of alligators and birds
II. Background information on the alligator
* Archosaurs gave rise to the alligator sharing similar characteristics to the bird and have shown to have unidirectional airflow. (Claessens, 2004) * In alligators the air loops in a single direction through aerodynamic valves. (Sanders, 2010) * Lung is partitioned and was also used to reserve oxygen. (Roux, 2002) * Alligators have 3 rows of lung chambers, which increase gas exchange and other needs. (Duncker, 2004)
III. Background information on the bird
* Archosaurs also gave rise to the bird as well and have unidirectional air flow. (Claessens, 2004) * Oxygen in birds goes through the parabronchi which is tube similar to the function of alveoli where air flows in one direction. (Sanders 2010) * Tubular structure which is ventilated by unidirectional air flow that allows for higher consumption of oxygen when in flight unlike alligator. (Roux, 2002) * In birds air moves constantly through the lungs because of the air sacs in which oxygen directly enters. This allows them to take twice as much as oxygen by storing the oxygen into the air sacs. (Duncker, 2004)
IV. Air Sacs/Alveoli
* Birds have developed air sacs. There is a physical separation between the lungs and air sacs which permits unidirectional ventilation. (Maina, 2006) * Alligators showed signs of hyperventilation when put through exercise. They’re respiratory system does not include air sacs and don’t endure high altitudes so oxygen consumption is low.(Carrier 2000) * Alligators have similar respiratory systems as humans and have to breathe. Air flows through bronchi then leaves through the same pathway unlike birds. (Sanders, 2010) * Air flows tidally into and out of the alveoli in these reptiles. (Claessens, 2009) * Birds with air flow that’s flows in one direction there is no residual volume and with a crosscurrent so more air flows in. (Rueben, 2004) * Alligators when inhaling oxygen, the oxygen skip the first branch and goes to the second. Then goes through the branches and chambers and comes back to the first branch. Similarly following the same pathway it entered and forming a loop using the aerodynamic valves. (Sanders, 2010)
* Alligators don’t have the exact same lung structure as birds but they do share similarities as seen in the unidirectional flow of air through the lungs. (Sanders, 2010) * Respiratory systems are specific for both organisms and are made based on their locomotive needs. (Duncker, 2004) * All archosaurs all have faveolar lungs and living ones have four chambered hearts. (Ruben, 2009) * The advantage of having air sacs is one of main important differences between the organisms allowing the birds to take in more oxygen when flying unlike alligators who also can store oxygen but can’t take in as much as birds and other mammals who are completely designed to do so. (Farmer, 2010)
Duncker HR. Vertebrate lungs: structure, topography and mechanics. A comparative perspective of the progressive integration of respiratory system,
locomotor apparatus and ontogenetic development. This article introduces the process of ventilation systems of fish, amphibians, and land animals. Provides information on how the reptiles lungs are chambered into 3 sections and avians have volume constant lungs with air sacs for intake of oxygen.
Quick DE, Ruben JA. Cardio-pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs. J Morphol. 2009 Oct;270(10):1232-46. Archosaurs which includes birds have a lung structure different then most organisms. This article explains the structure of the air sac...