PULMONARY OR MINOR CIRCULATION: ROUTE AND FUNCTIONS - ANATOMY AND PHYSIOLOGY - 2024

It is known as pulmonary circulation or minor circulation to a transport system that goes from the heart to the lungs and that allows the exchange of blood gases.

Through the pulmonary artery, the deoxygenated blood reaches the lungs where it releases carbon dioxide and receives oxygen. This oxygenated blood returns to the heart through the pulmonary veins and enters the systemic or greater circulation.

From Arcadian - http://training.seer.cancer.gov/module_anatomy/images/illu_pulmonary_circuit.jpg, Public Domain, Blood vessels, arteries and veins, along with the heart, are the organs that make up the circulatory system. In the case of pulmonary circulation, the main elements involved are the heart, the vena cava, the pulmonary arteries and veins, and the lungs.

The heart is a muscular organ that consists of four internal chambers, two right and two left. The rights are those involved in pulmonary circulation. In turn, the vena cava is responsible for transporting deoxygenated blood to the right side of the heart. From there it goes to the lungs where the exchange of carbon dioxide for oxygen occurs.

Oxygenated blood reaches the left side of the heart through the pulmonary veins, and from there it begins its journey into the systemic circulation.

Systemic or greater circulation is the part of the circulatory system that is responsible for carrying blood with oxygen to all organs and tissues of the body, in order to ensure its proper functioning.

In this way, both parts of the circulatory system are closely linked and the balance of the body depends on the correct functioning of both mechanisms.

Pulmonary circulation

The pulmonary circulation is a system that moves deoxygenated blood from the heart to the lungs. The organs involved in this mechanism are the heart, lungs, vena cava, pulmonary arteries and veins.

By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, In the lungs, the exchange of carbon dioxide for oxygen occurs and that oxygenated blood is transported back to the heart to be distributed throughout the body through the aorta artery.

The mechanism by which oxygenated blood reaches the organs and tissues of the body is called systemic or major circulation.

Development in the fetus

Approximately 15 days after fetal implantation, there is already evidence of the formation of blood vessels around the embryo. These primitive blood vessels ensure the vitality of the fetus and are essential for its nutrition and growth.

Between the third and fourth week of gestation, the heart is formed. This is a muscular, hollow organ that contains four chambers separated by partitions.

By the fifth week the fetus already has a fully formed and functioning four-chamber heart.

Fetal circulation is a completely different mechanism from that of the newborn, because the fetus receives all its nutrients from the placenta. In addition, the gas exchange is done through the mother.

By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, Once outside the uterus, when the newborn takes its first inspiration of ambient air, the change in pressures gives rise to the pertinent modifications, and the respiratory and circulatory system of the fetus is canceled, giving way to the mature circulatory system of the newborn, which is identical to the adult.

Anatomy and tour

The organs of the circulatory system that are involved in pulmonary circulation are the heart, lungs, vena cava, and pulmonary arteries and veins.

The heart is a muscular organ that acts as a reservoir and as a blood driving pump. It contracts regularly, at the rate of 60 to 80 beats per minute, by means of an automatic mechanism. Each heartbeat propels blood into different blood vessels.

Diagram of the human heart showing its parts (Source: Diagram_of_the_human_heart_ (cropped) _pt.svg: Rhcastilhosderivative work: Ortisa via Wikimedia Commons)

The inferior vena cava is a vein with a wide lumen, which is formed from the confluence of all the small veins of smaller caliber that are found throughout the body. It empties directly into the right part of the heart and is responsible for transporting non-oxygenated blood to the heart.

From the heart, the pulmonary arteries carry non-oxygenated blood to the lungs. They are the only arteries in the body that carry blood without oxygen.

The lungs are organs that deal with the mechanism of respiration and blood gas exchange. This exchange occurs in microscopic structures in the lungs called the pulmonary alveoli.

Public Domain, Within each alveolus there is a network of small blood vessels and specialized cells that, where non-oxygenated blood releases carbon dioxide and receives oxygen to re-enter the heart through the pulmonary veins. These are the only veins in the body that carry oxygenated blood.

Features

The main function of the minor circulation is to mediate gas exchange, to ensure that oxygenated blood reaches the organs through the major circulation.

Public Domain, Once the blood receives oxygen and re-enters the left chambers of the heart, it is propelled through the aorta artery to be distributed in all the organs and tissues of the body.

Oxygen is an essential element for the functioning of cells, therefore both parts of the circulatory system are equally important to guarantee the balance of the organism.

Physiology of respiration

Respiration is a mechanism through which oxygen enters the body and carbon dioxide is expelled. This occurs through inspiration and expiration, which are the breathing movements of taking in and expelling air, respectively.

From Lord Akryl (original author), Jmarchn; translated by Angelito7 - File: Illu conducting passages.svg, Public Domain, Living things that need oxygen for your body to function properly are called aerobes. Breathing is an indispensable and essential process to ensure your life.

Man is an aerobic being. The complexity of the work of the cells throughout your body requires an adequate supply of oxygen at all times, this endowment is guaranteed through respiration and pulmonary circulation.

The lung is the main element of the respiratory system. It is an even organ that is located in the rib cage, protected by the ribs.

Inside the lungs there is a tubular network that ends in microscopic structures called pulmonary alveoli. In the two lungs of an adult there are approximately 500 million alveoli, and it is at this level that gas exchange occurs.

From helix84 - en: Image: Alveoli.jpg, CC BY 2.5, Oxygen from the environment enters the lungs through inspiration of air. From the lungs, through a complex process, oxygenation of the blood is achieved.

In turn, the deoxygenated blood expels carbon dioxide that leaves the body through expiration.

References

1. Boyette LC, Burns B. (2019). Physiology, Pulmonary Circulation. StatPearls. Treasure Island, FL. Taken from: nlm.nih.gov
2. Jain V, Bhardwaj A. (2018). Physiology, Pulmonary Circulatory System. StatPearls. Treasure Island, FL. Taken from: nlm.nih.gov
3. Lee, G. (1971). Regulation of the pulmonary circulation. British heart journal. Taken from: nlm.nih.gov
4. Leigh, JM (1974). Pulmonary circulation and ventilation. Postgraduate medical journal. Taken from: nlm.nih.gov
5. Haddad, M; Sharma, S. (2019). Physiology, Lung. StatPearls. Treasure Island, FL. Taken from: nlm.nih.gov