We explain what major and minor circulation is in the human body, the characteristics, functions and route of each one.
What is major circulation and minor circulation?
The circulatory system of the human body is a double closed circuit composed of the heart, arteries, veins and blood capillaries. It is called “double” because the blood passes through the heart twice, without mixing arterial blood with venous blood, each time through its own ducts.
These two circuits of blood circulation are called major circulation and minor circulation. Both circuits occur simultaneously.
However, they have different objectives, they occur through different ducts and even involve different sectors of the heart, which when pumping prints energy in both circuits at the same time. Therefore, to understand them it is better to see each circuit separately.
The greater circulation
The greater circulation, also known as the systemic circulation, gets its name because it travels the greatest distance within the body. Its function is to nourish all the tissues of the body bringing them blood rich in oxygen and nutrients essential for cellular metabolism.
This circuit begins in the left ventricle of the heart from where the blood leaves directly through the aorta (crossing the aortic valve that prevents it from returning), and spreads through the arteries of the body, which then pass to the arterioles, becoming thinner, and culminate in the very fine network of capillaries that surround all the tissues.
There, the cells capture oxygen and nutrients. In exchange, they release carbon dioxide left over from cellular respiration, as well as other waste materials.
Then the blood passes to the venules also small, to begin its return journey, gathering all the deoxygenated and contaminated blood in the increasingly larger veins of the body, until it reaches the superior and inferior vena cava. It ends its journey in the right atrium of the heart.
The minor circulation
For its part, the minor circulation, also called pulmonary, It is responsible for transporting deoxygenated blood full of carbon dioxide to the lungs where a gas exchange occurs that expels the CO2 from the body and will replace it with oxygen from the air. Then it can return oxygenated to join the major cycle.
This circuit begins in the right ventricle of the heart with the blood that the right atrium drains from the entire body, and after passing through the pulmonary valve, it reaches the pulmonary artery, which then branches to carry the blood to the two lungs, one on each side of the heart.
Once in the lungs, the blood reaches the arterioles and then the capillaries, where hematosis can occur: the exchange of carbon dioxide for oxygen.
The blood, now rich in oxygen and free of CO2then begins a short path back towards the heart, through the pulmonary veins (two for each lung), which connect with the left atrium, completing the cycle and passing the baton to the greater circulation.
Continue with: Respiratory system
References
- “Pulmonary circulation” in Wikipedia.
- “Major and minor circulation” in Junta de Andalucía.
- “Major and minor circulation” (video) at Logos Academy.
- “Major and minor circulation” in Zonamédica.com.
- “The major and minor circuits of circulation” in radiological CORE.
