Artlabeling Activity the Layers of the Pericardium and of the Heart Wall
Layers of the heart
This article will hash out the layers of the heart (the epicardium, the myocardium and the endocardium) and any clinical relations pertaining to them.
In the same way that vehicles have their fuel pumps, our body has the heart. The middle is a muscular organ found in the heart mediastinum that pumps blood throughout the body. It is housed in the pericardial sac, which protects information technology and assists with its mechanics.
Recalling from the center beefcake, it has 2 atria and 2 ventricles that make upwards elements and important steps for the heart cycle. But permit's take a expect at the eye histology; it is essential for understanding the office of the heart. Histologically, the middle is made of three layers of tissue: epicardium, myocardium, and endocardium.
| Epicardium | Visceral layer of serous pericardium Comprised of mesothelial cells and fat and connective tissues |
| Myocardium | Muscle layer Comprised of cardiomyocytes |
| Endocardium | Lines inner surface of heart chambers and valves Comprised of a layer of endothelial cells, and a layer of subendocardial connective tissue |
| Clinical relation | Endocarditis |
Contents
- Epicardium
- Myocardium
- Endocardium
- Clinical relations: Endocarditis
- Sources
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Epicardium
The epicardium is the outermost layer of the eye. It is actually the visceral layer of the serous pericardium, which adheres to the myocardium of the heart. Histologically, it is made of mesothelial cells, the same as the parietal pericardium.
Beneath the mesothelial cells is a layer of adipose and connective tissue that binds the epicardium to the myocardium and cushions the heart. Nerves and blood vessels that supply the centre are found in the epicardium. At the roots of great vessels, the epicardium reflects back and continues as the parietal pericardium, forming an enclosed pericardial sac. The sac is filled with serous pericardial fluid that prevents friction during middle contractions.
One time you've finished learning almost the layers of the centre, showtime studying the main structures of the center with ourhandy diagrams, worksheets and quizzes.
Myocardium
The myocardium is functionally the principal constituent of the heart and the thickest layer of all iii heart layers. It is a muscle layer that enables heart contractions. Histologically, the myocardium is comprised of cardiomyocytes. Cardiomyocytes take a unmarried nucleus in the center of the jail cell, which helps to distinguish them from skeletal musculus cells that have multiple nuclei dispersed in the periphery of the cell.
Cardiomyocytes are very rich in glycogen deposits and mitochondria. This has a groovy functional significance since the myocardium is constantly contracting and needs a bully amount of energy at all times. Cardiomyocytes also comprise yellow lipofuscin granules. They don't have whatsoever particular functional significance, simply they are interesting since they are age markers for the jail cell. The older the prison cell, the more lipofuscin it has.
Cardiomyocytes communicate through special intercellular bridges called intercalated discs. The discs comprise of iii components: adherens junction (fascia adherens), desmosomes (maculae adherentes) and gap junctions (communicating junctions). These iii components enable mechanical unity of cardiomyocytes and a direct pathway of spreading action potentials. Because of this, the myocardium is observed as a form of syncytium, rather than a group of somewhat independent cells.
Although the structure of myocardium is the aforementioned in the atria and ventricles, information technology is thicker in the ventricles. This is due to the greater hydrostatic pressure that the ventricles must overcome when pumping the blood into the systemic vessels.
Endocardium
The endocardium is the innermost layer of the centre. It lines the inner surfaces of the heart chambers, including the heart valves. The endocardium has two layers. The inner layer lines the eye chambers and is made of endothelial cells. Superiorly, is the 2nd layer: a subendocardial connective tissue which is continuous with the connective tissue of the myocardium. Branches of the heart'southward conduction organisation are immersed into the subendocardial layer.
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Clinical relations: Endocarditis
Endocarditis is an inflammation of the endocardium. Normally, it has an infectious etiology. It generally affects already damaged heart valves and in most cases, is caused by the leaner Streptococcus viridans. In the case of a salubrious middle, the pathogenic leaner is Streptococcus aureus. No affair what bacteria is the cause, pathogenesis is the aforementioned. Once the bacteria carried past the bloodstream reaches the heart valves, they invade the endocardium. Then they cause the destruction of centre tissue, which leads to the germination of friable vegetations composed of necrotic droppings (destructed heart cells), thrombi, and microorganisms. Parts of the vegetation can be loosened by the bloodstream and disseminated throughout the body, forming secondary deposits of infection. If the causing bacteria is very virulent, the endocarditis has a fulminant grade and often a fatal outcome. On the other manus, when the leaner are not then virulent they can persist for some time in the center causing valves deformities.
It is interesting that Streptococcus viridans is normally found in the oral cavity, where the easiest way for it to achieve the heart and form vegetations on damaged valves is during a stomathology procedure. For this reason, it is necessary to inform your doctor if you have a valve problem, so they could prescribe antibiotics for precautions.
Usual symptoms of endocarditis are flu-like signs, heart murmur, night sweating, shortness of breath, and chest pain during breathing. Infectious endocarditis is treated by intravenous antibiotics for 2 to half dozen weeks. If the disease has significantly damaged the heart valves, information technology is indicated to perform a valve replacement or repair surgery.
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