circulatory system of animals has gone a long way of formation in the evolutionary development of the world.It was formed in place of the primary rudimentary parts of body cavities that have been superseded by higher animals tsellomom or secondary body cavity.During ontogenesis the circulatory system of animals has become a universal role to fulfill, namely the transfer of nutrients, oxygen, metabolic products, hormones and other biologically important elements.Thus, it is an important system integrating the living body, which ensures its integrity.
the usefulness of the circulatory system zoologists isolated from such primitive fauna as nemertean, annelids, echinoderms, mollusks and insects, that is, those classes that belong to the type of invertebrate.Their common ancestor structure circulatory system was very primitive - small gaps system representing cavity without epithelial cells, which has not been ascertained blood flow direction.Modern invertebrates principle structure of the circulatory system is also very primitive: the two main longitudinal vessels - the ventral and dorsal lie above and below the intestine, respectively.And interconnected by transverse blood vessels that cover the intestines into the ring and have numerous branches to the internal organs and the integument.Thus, a feature of the system lies in the fact that the ventral blood vessel moves backwards, and on the back - forward.The function of the blood flow is provided by the rhythmic contraction of the back of the vessel.
In the evolution of the circulatory system of the animals improved in various ways in all classes.Its development is not highly originates from the circulatory system of invertebrates.This explains its main functional feature: the presence of muscle pulsating organ called heart, which appears in primitive chordates organized representatives - in cyclostomes.Also, the movement of blood occurs following the ventral vessel forward, and on the back - back.
circulatory system of vertebrates have a common plan of structure, complexity and perfection of which occurred gradually over evolutionary process.But not all were aromorphoses evolutionary adjustment, that is, progressive morphological and physiological changes.The increasing complexity of the organization or the structure can not be considered a progressive feature of the changes that will make the animal, it has acquired more highly.In evolutionary transformations of the circulatory system chordates undoubted aromorphosis was the development of the heart in the most ancient representatives, as well as the intensification of its activity and the formation of a closed circulatory system in class gnathostomatous.It is also important aromorphoses deemed conversion of the heart and great vessels in the separation flow venous and arterial blood of reptiles, birds and animals.
circulatory system of animals formed the heart and blood vessels.The heart - a hollow muscular organ that blood flow through the vessels, pumping her.From him all the bodies blood moves through the arteries, and from organs to the heart - through his veins.Heart in different classes of vertebrates can be either mono (in cyclostomes) and dvukamernym (fish), three-chambered (amphibians, reptiles) and a four-chambered (birds, mammals).Thus, the anatomy of the heart can determine the extent of the basal metabolism of the body and allows you to share animals for cold-blooded and warm-blooded.In primitive chordates, constantly living in the water, the simplest principle of organization of the circulatory system - it has a circulation.Yield animals on land requires more intense metabolism, characterized by the appearance of pulmonary respiration, and as a result, the occurrence of the second circulation, which is responsible for blood gas exchange in the lungs.The circulatory system of animals is difficult to organize, together with the full separation of circulation, it characterizes the four-chambered heart, and the availability of additional circles, such as the placenta, and the actual heart of Willis circulation.
