It is known as major circulation or systemic circulation to the path that the oxygenated blood makes through the blood vessels to reach the different tissues and organs of the body. Through this mechanism, the blood passes through the organs filling them with blood with oxygen.
In addition, it makes a change, extracting the blood without oxygen and taking it back to the heart for an oxygenation process. This process is known as minor circulation or pulmonary circulation.
From User: Lennert B - This file is derived from: Blutkreislauf Gleichwarme.svg:, CC0, The set of arterial and venous blood vessels, with the heart, is called the circulatory system. Its importance lies in the fact that it ensures the vitality of the organs by providing them with oxygen.
The main organ of this system is the heart, which is a muscular element that works like a pump and has an automatic mechanism for its contraction and filling. It contracts 60 to 80 times in a minute in the resting conditions of a healthy adult. These regular contractions are known as a heartbeat.
The heart consists of four chambers, separated by fibrous septa. This is why some authors speak of "right heart" and "left heart", making this differentiation because the functions of the right chambers are different from those of the left chambers.
The process by which oxygenated blood reaches the organs through greater circulation, ensures the life of the cells at all times and does so by maintaining the oxygen necessary for them to perform their functions properly.
Greater circulation
Greater circulation refers to the process by which blood previously oxygenated in the lungs leaves the left heart into the aorta and reaches the organs of the body for nutrition with oxygenated blood.
It is a complex system that is closely linked to the so-called pulmonary circulation or minor circulation, a mechanism in which oxygen-depleted blood reaches the lungs to exchange carbon dioxide for oxygen. The new oxygenated blood returns to the heart to begin the journey to the organs.
Travel
Systemic circulation begins when the left atrium receives oxygenated blood from the lungs. Once there, and through a contraction, this blood passes to the left ventricle and from there to the aorta.
The aorta, which is the artery that originates directly from the heart, is responsible for transporting blood with oxygen throughout the body, while the vena cava is responsible for collecting blood without oxygen and returning it to the heart.
By Internet Archive Book Images - https://www.flickr.com/photos/internetarchivebookimages/14580465517/Source book page: https://archive.org/stream/textbookofanatom00bund/textbookofanatom00bund#page/n171/mode/1up, No restrictions, The distribution of oxygenated blood occurs through other smaller blood vessels, which are branches of the main artery. Thus, the aorta is dividing throughout its journey and forming smaller arteries that ensure that all organs receive the blood necessary for their proper functioning.
By Mikael Häggström, based on work by Edoarado, Mariana Ruiz Villarreal (LadyofHats, Fred the Oyster, Mikael Häggström and Patrick J. Lynch - en: File: Aorta es.svg by Edoarado, based on: Arterial System en.svg by Mariana Ruiz Villarreal (LadyofHats) Coronary arteries.svg by Fred the Oyster and Mikael Häggström, based on: File: Coronary.pdf by Patrick J. Lynch, CC BY-SA 3.0, https://commons.wikimedia.org/w/index. php? curid = 59526386
Veins go the other way and carry oxygen-depleted blood from the organs to the heart. The small branches found in each organ are organized into larger vessels, until reaching the vena cava that ends its journey in the right atrium.
It is from there that the oxygenation process begins through the pulmonary circulation. Blood passes to the lungs to receive oxygen and begin a new journey.
Features
The objective that the oxygenated blood reaches the organs is to guarantee the supply of oxygen in the cells.
Oxygen is the main element for most cellular functions, therefore it is essential for the proper functioning of organs and the vitality of tissues.
In addition to this, the systemic circulation is responsible for transporting hormones and chemical elements necessary for some processes that take place in the body and that guarantee the balance of all body systems.
The process of systemic circulation is the main means of oxygen supply for organs in humans.
Heart and blood vessels
The organs involved in systemic circulation are the heart and blood vessels, the heart being the most important as it is the one that drives the blood to travel through the vessels.
The arterial and venous vessels have different but equally important functions within the circulation process.
The systemic circulation is ensured by the synchronized operation of all its elements.
- Heart
The heart is a muscular, hollow organ, separated by fibrous partitions that form four chambers inside. It is located in the center of the thorax, behind the central bone called the sternum.
Public Domain, Its activity begins from the third week of gestation, when the fetal heartbeat can already be heard through specialized tests.
By the fourth week of gestation, the internal partitions have already formed and the heart is definitely divided into four chambers. For this week, in addition, the formation of the main arteries derived directly from this organ ends.
Physiology
The heart consists of four chambers, two upper chambers called atria and two lower chambers called ventricles.
For practical purposes and the best understanding of their function, it is preferred to describe a right heart and a left heart, even though all these chambers are within the same organ.
The atria and ventricles are separated by septa in the longitudinal axis, but they are linked together through valves that allow the exchange of blood. Thus, the atrium and right ventricle are separated from the left chambers by partitions, but interconnected by flexible valves.
The heart has an automatic system that guarantees its regular contraction. Each contraction pushes blood into the blood vessels to begin its journey through the body.
Contractions of the heart are called a heartbeat or pulse. In a healthy adult who is at rest, the normal pulse is 60 to 90 beats per minute. The elevation above the upper number is called tachycardia and the decrease below the lower one, bradycardia.
In conditions such as exercise or agitation, it is considered normal for an individual to have a heart rate above 90 without this implying a pathology. Similarly, those who exercise hard on a regular basis may have a normal resting heartbeat below 60.
- Blood vessels
Blood vessels are tubes that are responsible for conducting the blood that drives the heart to the different organs.
From Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below) Bartleby.com: Gray's Anatomy, Plate 505, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 425709
Its formation in the fetus occurs from the fourth week, but the complete system and fetal circulation does not occur until the eighth week of gestation.
They are divided into arteries and veins. Both are made up of muscle cells that contract to give continuity to their movement.
Arteries and veins differ in that the former carry oxygenated blood from the heart to the organs, while the latter travel from the organs to the heart, transporting blood without oxygen.
The main arteries involved in the systemic circulation are the aorta and the pulmonary arteries, and the main veins are the vena cava and the pulmonary veins.
References
- Pittman, RN (2011). The Circulatory System and Oxygen Transport. Taken from: nlm.nih.gov
- Rehman I, Rehman A. Anatomy, Thorax, Heart. (2019). StatPearls, Treasure Island. Taken from: nlm.nih.gov
- Buckberg, G. D; Nanda, N. C; Nguyen, C: Kocica, MJ (2018). What is the heart? Anatomy, Function, Pathophysiology, and Misconceptions. Journal of cardiovascular development and disease. Taken from: nlm.nih.gov
- Tucker, WD; Mahajan, K. (2019). Anatomy, Blood Vessels. StatPearls, Treasure Island. Taken from: nlm.nih.gov
- by Micheli Serra, A; Iturralde Torres, P; Aranda Fraustro, A. (2013). Origins of the knowledge of the structure and function of the cardiovascular system. Archives of Cardiology of Mexico. Taken from: scielo.org.mx