A group of lizards called a lounge. The lizard has 8 cervical vertebrae – this provides mobility of the head. To the thoracic vertebrae on each side is articulated along the rib. The other end of each rib, with the help of cartilage, fuses with the unpaired chest bone.
As a result, a thorax is formed, which protects the lungs and heart of the animal. There is no cutaneous respiration in the lizard. It breathes extremely light, which has a more cellular structure than the frog, which increases the surface of gas exchange in the lungs. The heart is three-chambered and consists of two atria and a ventricle. Unlike amphibians, the lizard’s ventricle is provided with an incomplete internal septum that divides it into the right (venous) part and the left (arterial) part.
Despite the great complexity of the structure of the lungs and the heart of the lizard (compared to amphibians), the metabolism in its body is still quite slow and depends on the temperature of the environment. Therefore, in warm weather, lizards are active, and when cold it, like all other reptiles, become sluggish.
Digestive, excretory and nervous systems of lizards are similar in structure to the corresponding systems of amphibians. In the brain, the cerebellum, which controls balance and coordination of movements, is developed somewhat more than in amphibians, which is associated with greater lizard mobility and a significant variety of its movements.