We explain one of the most essential vital organs, piece by piece.
In this article we will talk about the different parts that make up the human heart, also briefly describing their different functions and peculiarities.
- We recommend:”Chest pain: symptoms, and most frequent causes”
The 18 parts of the human heart and how they work
The human heart has a curious morphology. Located behind our sternum, slightly to the left, it is protected by the ribs and attached to the lungs, which have their own network of circulation with the heart, through which the blood is enriched with oxygen and releases its carbon dioxide before recirculating through the heart to the rest of the body.
It is a muscular organ and not entirely symmetrical, since the muscles on the left side of the heart are stronger and bulkier (since they are responsible for sending blood throughout the body, instead of only through the circulatory system pulmonary). It is surrounded by protective tissue, blood vessels, and specialized cells that help it keep its contractions rhythmic.
Below we list the different parts of the heart, as well as a brief description of their functions and peculiarities:
1. Myocardium
The myocardium is the contractile muscle layerthat performs the mechanical action of pumping blood in the body. It is a muscle that works involuntarily, that is, without the need for a nerve impulse coming from the nervous system. The contractile signal is generated in the heart itself.
Myocardium is more abundant in the lower part of the heart, the ventricles, than in the upper part, the atria. It is also more present in the left than in the right part of the heart.
2. Endocardium
The endocardium is the lining of the different chambers of the heart. It is made up mainly of endothelial cells, similar to the rest of the blood vessels, as well as a layer of loose connective tissue.
3. Pericardium
The pericardium is a fibrous membrane that surrounds the heartand the large blood vessels that connect to it, for insulation and protection. We can think of the pericardium as a large bag, made up of two layers: the serous pericardium and the fibrous pericardium.
Its viscosity and protective capacity allow the heart to move freely without being affected by nearby structures.
4. Right atrium
The right atrium is the cavity that is located in the upper right area of the heart, above the right ventricle. It is reached by the superior vena cava and the inferior vena cava, whichcarry the blood that has already circulated through the body, rich in carbon dioxide and poor in oxygen, to the heart. The blood reaches the right atrium before going down to the right ventricle.
5. Right ventricle
The right ventricle is attached to the right atrium, from which it receives blood. The right ventricle is also connected to the pulmonary artery, which will be responsible for carrying blood from the right ventricle to the lungs, where gas exchange will occur. It contracts slightly before the left ventricle.
6. Tricuspid valve
Between the atria and the ventricles, as well as between the ventricles and the arteries, we find the valves. They are made up of connective tissue and their main function is toPrevent Blood Reflux and isolate both the atria and the ventricles.
They open only when blood is pumped through them, and close immediately by the contractile action of the myocardium.
The tricuspid valve is the one between the right ventricle and the right atriumtag. It is called tricuspid because it is made up of three sheets of connective material, attached to the right ventricle through tendons and the small papillary muscles.
7. Pulmonary valve
The pulmonary valve is the one that connects the right ventricle with the pulmonary artery. It opens when the right ventricle contracts, letting blood into the artery.
8. Left atrium
The left atrium receives blood from the pulmonary veins (there are 4, two coming from the right lung and two coming from the left). From the left atrium, the blood goes to the left ventricle, through the mitral valve.
9. Left ventricle
The left ventricle contains the strongest muscles in the entire hearttag. From this ventricle, blood is pumped into the aorta, which divides to supply the rest of the body with blood. The blood pressure generated by this ventricle must be much greater than that generated by the right ventricle.
10. Mitral Valve
The mitral valve is the one that separates the left atrium from the left ventricle. Like the tricuspid valve, it is also attached to the ventricle through papillary tendons and muscles, which prevent its opening when the ventricle is empty as well as its opening when the ventricle contracts.
11. Aortic valve
The aortic valve is the one that separates the aorta artery from the left ventricle. It has to be able to withstand high blood pressure.
12. Tendinous cords
The tendinous cords are connective tissue structures that join the mitral and tricuspid valves with the papillary muscles.
13. Papillary muscles
The papillary muscles are found in the wall of the ventricles. They are cone-shaped and their main function is tokeep the valves closed to prevent blood reflux, that is, the blood goes backwards in the cardiac circuit.
14. Sinoatrial node
The sinoatrial node is a cluster of cells that function as the Natural Pacemakerof our heart, indicating when it has to contract. The electrical signal begins in the sinoatrial node, but travels through specialized structures from the top to the bottom of the heart, causing muscle contraction.
15. Atrioventricular node
The atrioventricular node is in a position close to the sinoatrial node. It also has the ability to function as the pacemaker of the heart, but it will only do soin the event that the sinoatrial node failstag. Impulses from the atrioventricular node are less frequent than those from the sinoatrial node.
16. Atrioventricular bundle
The atrioventricular bundle, also known as the bundle of His, is a cord-like muscular structure that functions as the cable through which the excitatory impulse from the nodes travels from the atria to the ventricles.
17. Coronary arteries
The coronary arteries surround the heart, providing nutrients to the entire structure. These branch into the left and right coronary arteries, each supplying mainly the respective halves of the heart. Coronary artery disease isthe most common type of heart condition .
18. Coronary veins
The coronary veins are responsible for returning oxygen-poor blood from the heart and surrounding tissues back to the heart. Interestingly, these veins drain directly into the right atrium in a very efficient and elegant way.
Bibliographic references
- Susan Standring; Neil R. Borley; et al., eds. (2008). Gray’s anatomy : the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. ISBN 978-0-8089-2371-8.
- Anderson, Robert H.; Mori, Shumpei (2016). “Wilhelm His Junior and his bundle”. Journal of Electrocardiology. doi:10.1016/j.jelectrocard.2016.06.003. ISSN 0022-0736.
- Csepe, T., Zhao, J., Hansen, B., Li, N., Sul, L., & Lim, P. et al. (2016). Human sinoatrial node structure: 3D microanatomy of sinoatrial conduction pathways. Progress In Biophysics And Molecular Biology, 120(1-3), 164-178. doi:10.1016/j.pbiomolbio.2015.12.011.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.