The circulatory system of amphibians, crustaceans and reptiles

In this article I would like to consider what the circulatory system of amphibians differs from that of crustaceans and reptiles (reptiles). Representatives of these classes are similar in many respects, but differences are still present, and sometimes, not small ones. So, about everything in detail.

First of all, it should be noted that the circulatory system of amphibians is closed. The two-chambered heart has only pulmonary salamanders, the others have a three- chambered heart . The circulatory system of amphibians consists of two circles of blood circulation: large and small. The presence of the second circle is associated with the occurrence of pulmonary respiration in these animals. The heart is made up of two atria and a ventricle. In this case, the blood in the atria is different: in the right - mixed, more venous, and in the left - arterial. The walls inside the ventricle form folds that prevent mixing of venous and arterial blood. The arterial cone emerging from the ventricle is provided with a spiral valve. As for the arteries, the pulmonary-pulmonary are responsible for the transfer of venous blood to the skin and lungs; Sleepy - provide the upper body with arterial blood, mainly the head; And the arteries of the aorta carry mixed blood to the remaining organs. A small (or pulmonary) circle begins precisely with the pulmonary-pulmonary arteries. Then the blood enriched with oxygen is collected in the paired pulmonary veins that flow into the left atrium. In the arcs of the aorta and carotid arteries, which are located in organs and tissues, the great circle of blood circulation originates. Venous blood, flowing through the pair of front hollow veins and along the unpaired posterior hollow, is in the right atrium. Through the front hollow veins, the skin is oxidized from the skin, in this connection it is mixed in the right atrium. It is because of the presence and characteristics of mixed blood that amphibians are characterized by a low level of metabolic processes. Their body temperature is changeable and depends on the environment. It's one of the cold-blooded animals.

The circulatory system of reptiles is similar to that of amphibians, but nevertheless it is more adapted to the terrestrial way of life. In the reptiles, the heart is made up of two atriums that open into the ventricle. The cavity of this part of the heart is divided by an incomplete septum (except for crocodiles only). That is why the blood that comes from the atria is partially mixed. The arterial cone in reptiles is completely reduced. Two arcs of the aorta and a pulmonary artery independently begin in the cardiac ventricle. In his left half, the right aortic arch originates, which transfers arterial blood to the head, and also to the forelimbs. In the middle of the ventricle, the left arch of the aorta with mixed blood begins. The arcs are connected in the dorsal aorta, and the arteries that depart from it carry mixed blood to other organs of the body. And it is very saturated with oxygen, in contrast to that of amphibians, for example.

Unlike amphibians and reptiles, the circulatory system of crustaceans is unclosed. It can rightly be called the most primitive of all the classes examined. The blood in motion is caused by the beating of the heart, which is placed next to the gills. As such, blood vessels are present only in higher crustaceans, while in others blood flows freely through the cavities near the internal organs. Often it dissolves special respiratory pigments, they help to bind more oxygen.

As we see, the circulatory system of amphibians takes an intermediate position between that of crustaceans and reptiles. Reptiles are most adapted to various conditions of life, and in this an important role is played by the organization of the blood supply to their body.