A video displayed on the official Facebook page for thedodo.com appears to show successful CPR on a lizard that was found drowned in a swimming pool.
Lizards have a three chambered heart with left and right atria and a single ventricle – the interventricular septum is only partially complete but serves to channel deoxygenated blood to the pulmonary trunk and oxygenated blood to the circulation. Humans have a left and right atrium and a left and right ventricle.
In addition the atria in the lizard contract at different times, thus directing the flow of blood between the sponge-like arranged muscle bundles which form the major part of the ventricle. There are paired left and right aortic arches which join caudal to the heart to form a single dorsal aorta.
The trachea divides into two bronchii which open into the lungs without bronchioles. The lungs are simple hollow sacs with internal folds lined with faveoli (small sacs) for an increased surface area. In more advanced lizards, the lungs are further divided into interconnected chambers by few large septae.
Respiration, which is voluntary and dependant on blood carbon dioxide pressure (pCO2) and temperature, is aided by expansion and contraction of the ribs for gas exchange with the cardiovascular system. Lizards lack a diaphragm, which in humans provides important function in respiration — contracting and causing the volume of the thoracic cavity to increase and the internal pressure to decrease, drawing air into the lungs.
Ribs are present on all vertebrae except tail and cervical vertebrae. Remember, some lizards are capable of autotomy — dicarding their tail to escape predators or danger.
Some lizards can revert to anaerobic metabolism during prolonged periods of apnea.
WikiVet Category: Lizard Anatomy
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