WHAT TYPES OF BLOOD CIRCULATION ARE THERE? - BIOLOGY - 2025

There are two types of blood circulation: minor or pulmonary, and major or systemic. Broadly speaking, it can be said that the lower or pulmonary blood circulation is the process through which the blood is oxygenated.

On the other hand, in the major or systemic blood circulation, the blood is released from oxygen and transfers it to all the organs of the body, from the upper to the lower extremities.

Both minor and major blood circulation occur in the body, and are complementary processes, dependent on each other. These types of circulation are typical of the closed, double and complete circulatory systems, characteristic of vertebrate animals.

Before detailing the characteristics of each type of blood circulation, it is important to understand the particularities of the different circulatory systems that exist in all organisms.

Each system has certain characteristics and is designed specifically for each species, according to its peculiarities.

Not all beings have the same circulatory system: for example, the systems of invertebrate organisms are very different from the systems of vertebrate beings, because the functions of each individual require a type of circulatory system.

Before explaining the types of blood circulation, the different types of circulatory systems that exist will be mentioned; Thus, it will be possible to understand how the circulatory system works, a basic element to understand the different types of circulation that occur in the body.

Types of circulatory systems

There are basically three categories of blood circulation systems, and each one has very specific characteristics. Blood circulatory systems can be:

Open or closed

An open blood circulation system is one in which blood is distributed directly to the organs through different channels.

That is, the blood does not always travel in the same way and ends up covering the organs. This system can be found in invertebrate organisms, such as mollusks and arthropods.

On the other hand, the closed circulation system is more complex, because the blood always travels within the blood vessels intended for it.

So the organs are not flooded with blood from the outside, but the blood enters the organs through valves.

The closed circulation system is characteristic of larger vertebrate animals. Humans possess this type of circulation system.

Complete or incomplete

Oxygenated blood and non-oxygenated blood circulate within the body. In complete circulation systems, both types of blood remain separate, without mixing.

In contrast, in incomplete circulating systems, oxygenated and non-oxygenated blood mix.

Human beings have a complete circulatory system. The incomplete system is unique to reptiles.

Single or double

In simple circulation systems, blood is pumped through the heart only once. In the case of dual circulation systems, blood passes through the heart twice. Humans have a dual circulation system.

Types of blood circulation

It can be said that human beings have a double, closed and complete circulatory system. It is a dual system because blood enters the heart twice: first from the lungs and then from the rest of the body.

It is a closed circulation system because blood is distributed throughout the body through specific conduits, the blood vessels, whose function is precisely that.

And it is a complete system because oxygenated and deoxygenated blood does not mix inside the body, but is oxygenated in one area and deoxygenated in other areas.

Now, since the general characteristics of the human blood circulation system have been identified, it is possible to describe the types of blood circulation that occur within the body.

In closed circulatory systems (those in which blood is pumped twice by the heart), two major types of blood circulation are generated: minor or pulmonary, and major or systemic.

Minor or pulmonary blood circulation

From Arcadian - http://training.seer.cancer.gov/module_anatomy/images/illu_pulmonary_circuit.jpg, Public Domain, In this type of circulation, blood leaves the heart's right ventricle and returns through the left atrium. Blood leaves the heart, travels to the lungs through the pulmonary artery, is charged with oxygen, and returns to the heart through the pulmonary veins.

In the middle of this process, hematosis is generated, a gas exchange in which the blood becomes oxygenated and releases the carbon dioxide it contains.

Major or systemic blood circulation

Parts of the heart. Source: Diagram_of_the_human_heart_ (cropped) _pt.svg: Rhcastilhosderivative work: Ortisa

In the case of this type of circulation, blood travels from the left ventricle of the heart and reaches the right atrium. This transfer is made through the aorta, which is the largest and main artery in the body.

Other arteries arise from the aorta artery, and its importance lies in the fact that it meets fundamental objectives regarding the flow of blood in the body, because it crosses the entire structure, reaches from the heart to the pelvic area, where it branches in other smaller arteries.

Through the process of major or systemic blood circulation, the body carries oxygenated blood throughout the body, except for the lungs, which allows the body's organs and cells to fill with oxygen. After its journey, the blood returns to the heart, already deoxygenated and full of carbon dioxide.

Within the greater blood circulation are the portal circulation. This refers to the passage of blood through the liver before returning to the heart.

In the process of greater circulation, the blood that comes from some organs (such as the stomach, pancreas, intestines and spleen) first passes through the liver, which works as a filter, and then it is incorporated into the veins that will carry it back to the heart.

Blood enters the liver through two channels: the hepatic artery, which is a branch of the aorta artery; and the portal vein, which is the one that carries blood from the spleen and digestive organs.

References

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