As perhaps confirmed by their ubiquity on nature cable channels, crocodiles are among natures most fearsome predators. When the opportunity arises, crocodilians will gorge, voluntarily consuming meals weighing 23% of their own body weight. This is analogous to a 130 -pound woman eating, at one sitting, a hamburger weighing 30 pounds. But what to do with all of that food" If they do not digest their meal quickly, crocodilians risk death from within, or if they are young, by predators.
While it has long been known that reptiles have the ability to shunt blood past their lungs, the physiological function of this ability is poorly understood. In a breakthrough article for the March/April 2008 issue of Physiological and Biochemical Zoology, The Right-to-Left Shunt of Crocodilians Serves Digestion, Professor C.G. Farmer and her colleagues at the University of Utah, along with the Utah Artificial Heart Institute, were able to demonstrate through their experiments with American alligators that the bypass function is central in their digestion process, and ultimately, their survival.
After feasting, crocodilians like to find a warm place to lie down while they digest their meal. Although on the outside this behavior seems ordinary, inside their bodies an extraordinary event takes place. During this period of digestion crocodilians divert blood through a special vessel that bypasses the lung, named the left aorta. Humans, other mammals, and birds lack this special vessel, and so all blood pumped by the right side of the heart flows through the pulmonary artery into the lungs, where carbon dioxide (CO2) moves from the blood into the gases of the lungs. Crocodilians can chose not to use the left aorta, in which case their cardiovascular system is very much like the mammalian system. However, when crocodilians are digesting a meal, they chose to shunt and direct CO2-rich blood straight to the stomach where glands make use of the CO2 to form gastric aci
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