Respiratory system
- 1. Respiratory System in Reptiles All reptiles breathe through their lungs. The reptile lung has a much greater surface area for the exchange of gases than the lungs of amphibians. Many reptiles’ lungs have little sacs called alveoli, across which gas is exchanged. This makes their lungs much more efficient than those of amphibians. Lung ventilation is done differently in each main reptile group. In squamates (scaled reptiles such as lizards and snakes), the lungs are ventilated almost exclusively by the muscles of the chest wall. These same muscles are used during movement, so most squamates have to hold their breath while exerting themselves (running fast).
- 2. Reptiles depend entirely on their lungs for respiration. Lizards do not have a diaphragm; instead, their chest muscles move the chest wall, which inflates and deflates the lungs. A few lizard species use their throat muscles to “gulp” air in a process called buccal pumping (a process also used by amphibians). Animals that use the “buccal pump” method take in air through the nose and move the floor of their mouth or throat up and down in a way that makes the animal look as if it were gulping air. When its mouth is full of air, the lizard will push the air down into the lungs. The nostrils are then closed, the glottis opened, and the floor of mouth is raised, forcing the air into the lungs for gas exchange. To deflate the lungs, the process is reversed. Mammals, in contrast, use their thoracic diaphragm to inflate and deflate the lungs more directly. .
- 3. Crocodilians actually have a muscular diaphragm that is similar to the mammalian diaphragm. The difference in crocodilians is that the muscles for their diaphragm pull part of the pelvis back, which brings the liver down and frees space for the lungs to expand. Unlike other vertebrates, most reptiles lack a secondary palate, which is a division between the nasal cavity and the oral cavity. Therefore, reptiles must hold their breath while swallowing. Crocodilians have evolved a bony secondary palate that allows them to continue breathing while remaining submerged. THE END.