Types of blood circulation

Animals have different types of blood circulation. Humans, for example, have a closed circulatory system and complete double circulation.

Human circulation is twofold and complete
Whenever we think of blood circulation, we imagine blood flowing through the blood vessels, being pumped by the heart. . However, not all animals have the same type of circulation and circulatory system .

The circulatory systems of animals can be divided into two main groups: open circulatory system or closed system.

– Open circulatory system: It is that type of system in which the blood fluid, also called hemolymph, also circulates outside the vessels, falling into cavities and gaps between the organs. In these gaps the blood meets the cells directly, exchanges substances and returns to the heart. Arthropods and some molluscs have this type of circulatory system.

– Closed circulatory system: In this type of system the blood is only inside the blood vessels. It is a more efficient type when compared to the open one, since the transport speed is superior thanks to the pressure . In this system it is possible to observe arteries, arterioles, veins, venules and capillaries. The latter are the places where the exchange of substances takes place. Annelids , some molluscs and vertebrates have this type of circulatory system.

The circulatory system of annelids is closed

In addition to this classification, in vertebrates, we can divide the circulation into single or double.

– Simple circulation: It is the one in which the blood passes through the heart only once. In this case, the heart only has contact with blood rich in carbon dioxide, which is pumped to the gills where it undergoes the oxygenation process. It is a type of circulation found in animals that have gill breathing.

Dual circulation can be further divided into complete and incomplete.

Incomplete Circulation : The anatomy of the heart causes oxygen-rich blood to mix with carbon dioxide-rich blood. This type of circulation occurs in amphibians and reptiles. In the first group, a heart with three chambers (two atria and one ventricle) is observed. In reptiles, hearts with four cavities are completely separated in some species and, in others, a small opening is observed between the ventricles. Even in reptiles that have four well-separated cavities, blood mixes in the foramen of Panizza.

– Full circulation:It is the one in which the blood rich in oxygen does not mix with the blood rich in carbon dioxide. It occurs in birds and mammals , since they have a heart completely divided into four chambers: two atria and two ventricles.

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