Vertebrate animals have different body structure. The plan of the building all have in common. This proves the origin from one ancestor. However, the complexity of the organism varies. It is believed that the complexity of the structure was in the course of evolution. That is, first appeared in more primitive organisms.
The Course of evolution of vertebrates began with the lancetnik.
This body already has a notochord and neural tube. And also for the most primitive vertebrate heart: pulsating abdominal vessel.
The increasing complexity of the organization led to the formation of fish. Gill-breathing organisms have a two chamber heart and single circulation of blood.
Amphibians and most reptiles have three-chambered heart. It even boosts their energy.
Birds and mammals are at the top of evolution. The heart is made up of four chambers. There are no holes between the Atria, as well as between the ventricles. Two circles of circulation of blood completely separate. Therefore, birds and mammals have teplokeram that sharply distinguishes them from other animals. This group, of course, applies to people.
The amphibian and reptile heart has three chambers: two Atria and one ventricle. Scientists have found that it is this structure of the muscular body suitable for the life of these animals.
The Presence of two circles of circulation of blood provides a relatively high level of life. Animals with three-chambered heart live on land, they are quite agile (especially reptiles). They can tolerate a temperature drop, without falling into a stupor. Newts, for example, the first emerge from winter shelters when the snow is gone. Spring makes awaken and herbal frogs very early. These amphibians are jumping through the snow in search of a partner for reproduction.
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A three-chambered heart allows the amphibians to fall into a daze at the onset of cold. The circulatory system allows us not to waste a lot of energy for pumping blood, which would be observed in the presence of the heart with four chambers and complete separation of the two circles of circulation of blood.
Three-chambered heart with an incomplete septum have reptiles. You can see that their mobility increases dramatically in comparison with amphibians. The sand lizard is actually very agile. They are pretty hard to catch, especially in warm weather. However, the body temperature still depends on the environment. Reptiles-cold-blooded organisms.
Crocodiles have an unusual structure of the heart. Scientists refer to animals crocodiles, with four-chamber heart. Partition between the right and left ventricles has a large area. However, the hole in the wall exists. Therefore, crocodiles are cold-blooded creatures remain. Blood rich oxidizing element, mixed with blood, poor in oxygen. In addition, the special structure of the blood system of the crocodile expressed in the presence of left artery. It departs from the right ventricle along with the pulmonary. The left artery carries blood to the stomach of a crocodile. Such a structure contributes to a more rapid digestion of food. This is necessary because the reptile swallows large pieces of meat, which can begin to rot the long delay in the digestive tract.
A Heart with four chambers have birds and animals, suckling babies with milk. This is the most highly organized organisms. Birds are capable of prolonged flight, and the mammals to run fast. They all have teplokeram. They remain active in cold weather, which can not afford a cold-blooded representatives.
Hibernate only those organisms that are unable to provide themselves with food in the winter. Bear, has not received sufficient weight in the fall, wakes up and wanders through the snow in search of food.
Thus, a four-chambered heart maximize the life activity of organisms. Warm-blooded animals do not fall into a state of torpor. Their motor activity is not dependent on the ambient temperature. Such vertebrate animals thrive on land in conditions of strong gravity.
Animals with three-chambered heart has got two circles of circulation of blood. However, the large and small circles are not completely separated. Blood rich element oxidation, is mixed with blood saturated with carbon dioxide. Despite this, three-chambered heart provides life to organisms on land.
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