Anatomy the the Heart

The love is an body organ responsible because that pumping blood through the blood vessels making use of rhythmic contractions that cardiac muscle.

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Key Takeaways

Key PointsThe love is a four-chambered muscular organ containing one involuntary conduction system that initiates rhythmic contractions come pump blood throughout the body.The heart has its very own blood supply and also is managed by self-regulating nerve bundles called nodes.The SA and also AV nodes send impulses through the Purkinje fibers that reason muscle contractions to the heart.The love is composed of three layers: the epicardium (outer layer) which prevents excess expansion or movement of the heart, the myocardium (middle layer) which initiates contractions control the cardiac cycle, and the endocardium (inner layer) that lines the cavities and valves.The heart contains two top chambers referred to as atria and two lower chambers referred to as ventricles. The left and right political parties of the heart are separated by the septum.Valves stop the backflow of blood and also separate the atria indigenous the ventricle and also the ventricle from the pulmonary artery or aorta.Key Termsheart: A fist-sized muscular body organ in the chest that pumps blood through the body using involuntary contractions the cardiac muscle.ventricle: among two reduced chambers that the heart the receives blood from the atria and pumps the out into pulmonary or systemic circulation, relying on side.myocardium: The middle of the 3 layers developing the wall surface of the heart, include cardiac muscle tissue. Innervated by the Purkinje fibers.

The human being heart is the pump because that the circulatory system, and together with the circulatory system is taken into consideration to be an organ of the cardiovascular system. It is composed of four chambers and pumps blood with both systemic and pulmonary circulation to allow gas exchange and tissue oxygenation. The heart is situated in the thoracic cavity between the lungs and protected by the rib cage.

Structure the the Heart

The heart is composed of four chambers separated into two sides. Every side has an atria i m sorry receives blood into the heart and also flows it right into a ventricle, i m sorry pumps the blood out of the heart. The atria and ventricle on each side of the love are connected together by valves that avoid backflow the blood. The wall surface that separates the left and right next of the love is called the septum.

The left heart deals with systemic circulation, while the right heart faces pulmonary circulation. The left side of the heart receives oxygenated blood from the pulmonary vein and pumps it right into the aorta, when the ideal side the the love receives deoxygenated blood native the vena cava and pumps it into the pulmonary vein. The pulmonary vein and aorta likewise have valves connecting them come their particular ventricle.

The heart has its very own self-sustaining conduction system that sends out nervous impulses come cardiac tissue. The sinoatrial (SA) and atrioventricular (AV) nodes are bundles the nerve fibers that kind this conduction system. They are situated in the left atrial wall of the heart and send nerve impulses come a large, highly devoted set of nerves dubbed the Purkinje fibers, which subsequently send those nerve impulses come the cardiac muscle tissue. This nodes deserve to send impulses to the heart without central nervous mechanism stimulation, yet may be affected by worried stimulation to transform heart rate. The heart likewise has its own blood supply, the cardiac arteries that administer tissue oxygenation to the heart together the blood within the heart is not supplied for oxygenation through the heart.

Cardiac Histology

The love is enclosed in a double-walled safety membrane referred to as the pericardium, i beg your pardon is a mesothelium organization of the thoracic cavity. The twin membrane of pericardium includes pericardial liquid which nourishes the heart and also prevents shock. This composite sac protects the heart, anchors it to surrounding structures, and also prevents the heart from overfilling with blood.

The wall of the heart is created of 3 layers of various tissues. The outer layer is called the epicardium, or visceral pericardium, because it is likewise the inner wall of the pericardium. The center layer of the heart, the myocardium, and also contains devoted cardiac muscle organization responsible for contraction. Cardiac muscle tissue is unique from bones or smooth muscle since it pumps involuntarily based upon conduction native the AV and also SA nodes. The inner great is called the endocardium and is in contact with the blood that the love pumps. It also merges with the within lining the blood vessels and covers heart valves. Cardiac organization is irreversible tissue the does not heal or regenerate when damaged. As a result, is prone to scarring and also enlargement because of mechanical stress and also injury.


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The Mammalian Heart: The place of valves ensures proper directional flow of blood v the cardiac interior. Note the difference in the thickness the the muscled walls of the atrium and also the left and also right ventricle.


Key Takeaways

Key PointsThe pericardium is a mesothelium tissue of the thoracic cavity which surrounds the heart. The outer layer, the fibrous pericardium, is consisted of of dense connective tissue that protects the heart, anchors it to the bordering walls, and prevents the from overfilling.The inner great of the pericardium, the serous pericardium, is further split into two layers, an outer parietal layer and an within visceral layer with the pericardial cavity in between the 2 layers.The serous pericardium attributes to lubricate the heart through pericardial fluid, which is save on computer in the an are between the parietal and visceral layers.Pericarditis is inflammation the the pericardium, often as result of infection, which can constrict and put harmful press on the heart.Key Termsfibrous pericardium: created of thick connective tissue which protects the heart, anchors it to the bordering walls, and also prevents the heart from overfilling through blood.serous pericardium: situated deeper 보다 the fibrous pericardium, this structure contains two layers the lubricate the love to prevent friction from arising during heart activity.pericardium: A serous membrane the surrounds and protects the heart.

The pericardium is the thick, membranous, fluid-filled sac that surrounds the heart and also the root of the vessels that enter and also leave this critical organ, functioning together a protective membrane. The pericardium is among the mesothelium organization of the thoracic cavity, in addition to the pleura i beg your pardon cover the lungs. The pericardium is composed of two layers, an outer fibrous pericardium and also an within serous pericardium.


Membranes the the Thoracic Cavity: A transverse section of the thorax, reflecting the materials of the middle and also the posterior mediastinum. The pleural and pericardial cavities room exaggerated since normally there is no an are between parietal and visceral pleura and between pericardium and heart.


Fibrous Pericardium

The fibrous pericardium is the outer layer the the pericardium. It is created of thick connective tissue which anchors the heart to the mediastinum that the chest wall. It stays clear of the heart from overfilling with blood and also protects that from adjacent infections by completely separating the from the remainder of the thoracic cavity. The is consistent with the external fibrous layer of the neighboring an excellent blood vessels.

Serous Pericardium

The serous pericardium, the inner layer of the pericardium, is composed of two different layers. The external layer, the parietal layer, is totally adhered to the fibrous pericardium. The inner layer is recognized as the visceral layer, which covers and protects the good vessels and heart. The room between the parietal and also visceral class is dubbed the pericardial cavity.

The visceral great is referred to as the epicardium in the locations where that is in direct contact with the heart. The an are between these two serous layers, the parietal and also the visceral, is the pericardial cavity, which includes pericardial fluid. The serous pericardium, through its two membranes and also the fluid-filled pericardial cavity, gives protection come the heart and also a lubricated sliding surface ar within i beg your pardon the heart can move in an answer to its own contractions and also to the movement of surrounding structures such as the diaphragm and the lungs.

Function the the Pericardium

The pericardium is important due to the fact that it protects the heart from trauma, shock, stress, and also even infections from the surrounding lungs. It supports the heart and anchors it come the medastinum so the doesn’t relocate within the body. The pericardium lubricates the heart and also prevents it from coming to be too huge if blood volume is overloaded (though it will not prevent chronic love enlargement).

Despite these functions, the pericardium is still breakable to difficulties of that is own. Pericarditis is the term because that inflammation in the pericardium, commonly due to infection. Pericarditis is regularly a severe an illness because it have the right to constrict and also apply press on the heart and work against its normal function. Pericarditis come in many varieties depending top top which organization layer is infected.


Layers of the love Walls

The heart wall is comprised of 3 layers: the outer epicardium, the center myocardium, and also the within endocardium.


Learning Objectives

Distinguish in between the epicardium, myocardium, and also endocardium great of the love wall


Key Takeaways

Key PointsThe epicardium is a slim layer of connective tissue and also fat serving as secondary layer of protection for the heart. It is thought about a extension of the serous pericardium.The myocardium is the muscle tissue of the heart, written of cardiac muscle cells dubbed cardiomyocytes that get nervous stimulation native the sinoatrial (SA) and atrioventricular (AV nodes via the Purkinje fibers.Cardiomyocytes are much shorter than skeletal myocytes, and contain under nuclei. Cardiac muscle is striated.The endocardium is composed of endothelial cell that carry out a smooth, non-adherent surface ar for blood collection and also pumping and also may aid regulate contractility.An epidemic or inflammation of the endocardium is dubbed infective endocarditis.Key TermsPurkinje fibers: A bundle that nerve fibers situated under the endocardium, which it is provided nervous impulses to the mycardium’s cardiac muscle tissues.endocardium: A slim serous membrane that lines the internal of the heart and valves.cardiomyocyte: A cardiac muscle cell (or myocyte) in the heart, which provides up the cardiac muscle tissue.

The heart wall is made up of 3 layers, the epicardium (outer), myocardium (middle), and endocardium (inner). These organization layers room highly dedicated and perform different functions. Throughout ventricular contraction, the tide of depolarization indigenous the SA and AV nodes move from in ~ the endocardial wall surface through the myocardial layer come the epicardial surface of the heart.

Epicardium


The love Wall: The wall of the love is created of 3 layers, the thin outer epicardium, the thick middle myocardium, and also the really thin within endocardium. The dark area top top the heart wall surface is scar from a vault myocardial infarction (heart attack).


The outer layer the the heart wall is the epicardium. The epicardium refers to both the outer layer the the heart and also the inner class of the serous visceral pericardium, which is attached come the outer wall of the heart. The epicardium is a thin layer of elastic connective tissue and also fat the serves as an additional layer of defense from trauma or friction because that the heart under the pericardium. This layer has the coronary blood vessels, i m sorry oxygenate the organization of the heart through a blood supply from the coronary arteries.

Myocardium

The center layer of the heart wall is the myocardium—the muscle tissue of the heart and also the thickest layer of the love wall. The is composed of cardiac muscle cells, or cardiomyocytes. Cardiomyocytes are dedicated muscle cells the contract like other muscle cells, however differ in shape. Contrasted to skeleton muscle cells, cardiac muscle cells are much shorter and have fewer nuclei. Cardiac muscle tissue is additionally striated (forming protein bands) and also contains tubules and also gap junctions, unlike skeletal muscle tissue. Due to their consistent rhythmic contraction, cardiomyocytes call for a devoted blood supply to deliver oxygen and also nutrients and remove waste products such together carbon dioxide indigenous the cardiac muscle tissue. This blood it is provided is listed by the coronary arteries.

Endocardium

The inner great of the heart wall is the endocardium, composed of endothelial cells that provide a smooth, elastic, non-adherent surface ar for blood collection and also pumping. The endocardium might regulate metabolic waste removal from love tissues and act together a barrier between the blood and also the love muscle, thus managing the ingredient of the extracellular fluid in i m sorry the cardiomyocytes bathe. This consequently can affect the contractility that the heart.

This tissue also covers the valves that the heart and also is histologically constant with the vascular endothelium of the major blood vessels entering and also leaving the heart. The Purkinje fibers room located just beneath the endocardium and send concerned impulses native the SA and AV nodes external of the heart into the myocardial tissues.

The endocardium can come to be infected, a significant inflammatory condition called infective endocarditis. This and other potential troubles with the endocardium may damages the valves and also impair the normal flow of blood through the heart.


Chambers of the Heart

The heart has 4 chambers. The 2 atria get blood right into the heart and the two ventricles pump blood into circulation.


Key Takeaways

Key PointsThe right and left atria are the peak chambers of the heart and also receive blood into the heart. The appropriate atrium receive deoxygenated blood native systemic circulation and also the left atrium receives oxygenated blood from pulmonary circulation.The atria execute not have actually inlet valves, however are separated from the ventricles through valves. The atria facilitate circulation by allowing uninterrupted blood circulation into the heart during ventricular systole.The atria have several instrument in location to ensure the venous blood flow isn’t impaired, such as the lack of valves and also the visibility of light and brief contractions throughout atrial systole.The ideal ventricle pumps deoxygenated blood into pulmonary circulation. The left ventricle pumps oxygenated blood right into systemic circulation. The left ventricle is thicker due to the fact that systemic circulation requires a much bigger blood volume than pulmonary circulation.Systole explains contraction, once blood is pumped indigenous the heart into circulation through the ventricles. It can additionally describe atrial systole, in which blood move from the atria to the ventricles during ventricular diastole.Diastole explains relaxation, as soon as blood moves into the love while the ventricles prepare come eject that same blood during systole.Key Termsdiastole: The relaxation and dilation the the love chambers between contractions, throughout which they fill v blood.systole: The rhythmic convulsion of the heart whereby blood is ejected indigenous one chamber to the next, or the end of the heart and also into the arteries.

The heart is the complicated pump that the circulatory system, pump blood transparent the body for the objectives of tissue oxygenation and also gas exchange. The love has four chambers through which blood flows: 2 sets the each form of room (atria and also ventricles), one every side, every with distinct functions. The left side of the heart encounters systemic circulation when the right side of the heart deals with pulmonary circulation.

The Atria

The atria are chambers in i m sorry blood beginning the heart. Castle are located on the anterior finish of the heart, through one atrium on each side. The appropriate atrium obtain deoxygenated blood native systemic circulation v the premium vena cava and inferior venae cavae. The left atrium receives oxygenated blood indigenous pulmonary circulation through the left and right pulmonary veins.

Blood passively flows into the atria there is no passing v valves. The atria relax and also dilate (expand) while they fill through blood in a procedure called atrial diastole. The atria and ventricles are separated through the mitral and also tricuspid valves. The atria undergo atrial systole, a quick contraction of the atria that ejects blood from the atria through the valves and also into the ventricles. The chordae tendinae are elastic tendons that affix to the valve from the ventricles and also relax throughout atrial systole and ventricular diastole, but contract and also close turn off the valve during ventricular systole.

One the the defining characteristics of the atria is that they carry out not impede venous flow into the heart. Atria have 4 essential features that reason them to promote consistent venous flow:

There room no atrial inlet valves to interrupt blood flow throughout atrial systole. The venous blood start the heart has a an extremely low pressure contrasted to arterial blood, and valves would need venous blood press to build up end a long duration of time to go into the atria.The atrial systole contractions are incomplete and do no block circulation from the veins v the atria right into the ventricles. Throughout atrial systole, blood not only empties from the atria to the ventricles, yet continues to circulation uninterrupted from the veins appropriate through the atria into the ventricles.The atrial contractions are slight, preventing far-ranging back pressure that would certainly impede venous flow.The relaxation of the atria is coordinated to begin prior to the start of ventricular contraction, which also helps stop the heart from beating also slowly.

Ventricles

The ventricles are located on the posterior finish of the love beneath their equivalent atrium. The best ventricle obtain deoxygenated blood indigenous the right atria and pumps it with the pulmonary vein and into pulmonary circulation, i m sorry goes into the lungs for gas exchange. The left ventricle obtain oxygenated blood indigenous the left atria and pumps it through the aorta into systemic circulation to supply the organization of the body v oxygen.

The walls of the ventricles are thicker and stronger 보다 those of the atria. The physiologic load on the ventricles, i m sorry pump blood throughout the body and lungs, is much higher than the pressure created by the atria to fill the ventricles. Further, the left ventricle has thicker wall surfaces than the right because it pumps blood throughout the body, when the ideal ventricle pumps just to the lungs, which is a much smaller volume of blood.

During ventricular diastole, the ventricles relax and also fill with blood. Throughout ventricular systole, the ventricles contract, pumping blood with the semi-lunar valves right into systemic circulation.


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Structure the the heart: structure diagram of a coronal section of the human heart from an anterior view. The two bigger chambers space the ventricles.


Key Takeaways

Key PointsFive good vessels enter and leave the heart: the superior and inferior vena cava, the pulmonary artery, the pulmonary vein, and the aorta.The exceptional vena cava and inferior vena cava room veins the return deoxygenated blood native circulation in the body and also empty it into the right atrium.The pulmonary artery dead deoxygenated blood native the ideal ventricle into the lungs because that oxygenation.The pulmonary veins bring oxygenated blood native the lungs into the left atrium where it is went back to systemic circulation.The aorta is the biggest artery in the body. That carries oxygenated blood indigenous the left ventricle the the heart into systemic circulation.The aorta has plenty of subdivisions the branch off right into smaller arteries. This subdivisions are the ascending and descending aorta, the aortic arch, and also the thoracic and abdominal aorta.Key Termspulmonary arteries: The arteries that take deoxygenated blood far from the best side the the heart and also into the capillaries that the lungs because that the purpose of gas exchange.aorta: The an excellent artery i m sorry carries the blood indigenous the heart right into systemic circulation.venae cavae: The two huge vessels, the superior and also inferior vena cava, that carry deoxygenated blood from systemic circulation come the heart.

The human circulatory device is a dual system, meaning there are two separate systems that blood flow: pulmonary circulation and systemic circulation. The adult human being heart consists of two separated pumps, the appropriate side (right atrium and also ventricle,) which pumps deoxygenated blood right into the pulmonary circulation, and the left side (left atrium and also ventricle), i m sorry pumps oxygenated blood right into the systemic circulation. An excellent vessels are the major vessels that bring blood right into the heart and also away native the heart to and from the pulmonary or systemic circuit. The great vessels collect and distribute blood across the human body from countless smaller vessels.

The Venae Cavae


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The Systemic Circuit: The venae cavae and also the aorta type the systemic circuit, i m sorry circulates blood come the head, extremities and abdomen.


The superior and also inferior vena cava are jointly called the venae cavae. The venae cavae, together with the aorta, space the good vessels involved in systemic circulation. This veins return deoxygenated blood native the body right into the heart, emptying it right into the right atrium. The venae cavae space not separated from the best atrium through valves.

Superior Vena Cava

The exceptional vena cava is a large, brief vein the carries deoxygenated blood from the upper fifty percent of the human body to the best atrium. The right and also left subclavian veins, jugular veins, and also thyroid veins feed right into the remarkable vena cava. The subclavian veins are far-ranging because the thoracic lymphatic duct drains lymph liquid into the subclavian veins, do the premium vena cava a site of lymph liquid recirculation into the plasma. The superior vena cava begins above the heart.

Inferior Vena Cava

The worse vena cava is the largest vein in the body and also carries deoxygenated blood from the lower fifty percent of the body into the heart. The left and right common iliac veins converge to type the inferior vena cava at its lowest point. The inferior vena cava starts posterior come the abdominal cavity and travels come the heart alongside the abdominal aorta. Follow me the way up the human body from the iliac veins, the renal and also suprarenal veins ( kidney and also adrenal glands), lumbar veins (from the back), and hepatic veins (from the liver) all drainpipe into the inferior vena cava.

The Aorta

The aorta is the biggest of the arteries in systemic circulation. Blood is pumped from the left ventricle through the aortic valve right into the aorta. The aorta is a extremely elastic artery and is able come dilate and constrict in response to blood pressure and volume. When the left ventricle contracts to force blood v the aortic valve into the aorta, the aorta expands. This expansion provides potential energy to aid maintain blood pressure throughout diastole, once the aorta passively contracts. Blood push is highest possible in the aorta and also diminishes v circulation, getting to its lowest points in ~ the end of venous circulation. The difference in pressure between the aorta and right atrium accounts because that blood circulation in the circulation, as blood flows from locations of high push to locations of short pressure.

Components of the Aorta

The aortic arch has peripheral baroreceptors (pressure sensors) and also chemoreceptors (chemical sensors) the relay information worrying blood pressure, blood pH, and also carbon dioxide levels to the medulla oblongata that the brain. This details is processed by the mind and the autonomic nervous mechanism mediates the homeostatic responses the involve feedback in the lungs and also kidneys. The aorta extends approximately the heart and also travels downward, diverging into the iliac arteries. The five components of the aorta are:

The ascending aorta lies in between the heart and also the arch that aorta. It breaks off into the aortic sinuses, some of which kind the coronary arteries.The arch of aorta is the optimal of the aorta, which division off right into the left carotid artery, brachiocephalic trunk, and the left subclavian artery.The to decrease aorta is the ar from the arch of aorta come the point where it divides right into the typical iliac arteries. It is subdivided right into the thoracic and abdominal muscle aorta.The thoracic aorta is the part of the descending aorta over the diaphragm. That branches off into the bronchial, mediastinal, esophageal, and also phrenic arteries.The abdominal muscle aorta is the part of the descending aorta listed below the diaphragm, which divides into the iliac arteries and branches right into the renal and suprarenal arteries. This component of the aorta is vulnerable to bursting and hemorrhage (aneurysm) native persistently high blood pressure.

The Pulmonary Arteries

The pulmonary arteries carry deoxygenated blood indigenous the ideal ventricle right into the alveolar capillaries of the lungs to unload carbon dioxide and also take up oxygen. These are the just arteries that lug deoxygenated blood, and are taken into consideration arteries due to the fact that they lug blood far from the heart. The short, wide vessel branches right into the left and right pulmonary arteries that deliver deoxygenated blood to the particular lungs. Blood first passes v the pulmonary valve together it is ejected into the pulmonary arteries.


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Pulmonary circuit: diagram of pulmonary circulation. Oxygen-rich blood is shown in red; oxygen-depleted blood in blue.


The Pulmonary Veins

The pulmonary veins carry oxygenated blood native the lungs to the left atrium of the heart. Regardless of carrying oxygenated blood, this great vessel is still thought about a vein since it dead blood in the direction of the heart. 4 pulmonary veins go into the left atrium. The best pulmonary veins happen behind the best atrium and also superior vena cava when the left happen in front of the to decrease thoracic aorta. The pulmonary arteries and also veins are both considered component of pulmonary circulation.


Myocardial Thickness and Function

The myocardium (cardiac muscle) is the thickest section of the heart wall surface and contains cardiomyocytes, the contractile cell of the heart.


Key Takeaways

Key PointsCoordinated contraction of cardiomyocytes causes the love to contract and expel blood into circulation.The myocardium is thickest in the left ventricle, together the left ventricle must produce a most pressure to pump blood into the aorta and also throughout systemic circulation.Cardiac muscle has actually a high thickness of mitochondria and a huge blood supply, which keep it functioning continuously.Sarcomeres are the straightforward unit of muscle tissue, composed primarily of actin and myosin myofibrils.The heart’s thickness may adjust over time and adapt come compensate because that diseases, which often results in heart failure.Key TermsCardiac hypertrophy: one adaptive disease in i beg your pardon the walls of the heart come to be too special to pump blood effectively. It is generally a complication that hypertension.sarcomere: The straightforward contractile unit of contractile muscle, which contains myofibril filaments made out of myosin and actin, the 2 proteins that slide past one one more to reason a muscle contraction.cardiomyocyte: A cardiac muscle cabinet (myocyte) in the heart.

The myocardium, or cardiac muscle, is the thickest ar of the heart wall surface and consists of cardiomyocytes, the contractile cells of the heart. Together a kind of muscle tissue, the myocardium is unique amongst all various other muscle organization in the person body. The thickness the the myocardium determines the stamin of the heart’s capability to pump blood.

Myocardial Histology

The framework of cardiac muscle share some attributes with bones muscle, but has countless distinctive features of the own. Cardiomyocytes are much shorter than bones myocytes and also have fewer nuclei. Every muscle fiber connects come the plasma membrane (sarcolemma) through distinctive tubules ( T-tubule ). At this T-tubules, the sarcolemma is studded v a large number that calcium networks which permit calcium ion exchange in ~ a rate much quicker than that of the neuromuscular junction in bones muscle. The flux the calcium ions right into the muscle cells causes stimulates an activity potential, which causes the cells to contract.

Cardiac muscle, prefer skeletal muscle, is made up of sarcomeres, the basic, contractile units of muscle. Sarcomeres space composed that long, fibrous proteins the slide past each other as soon as the muscle contract and relax. Two of the important proteins found in sarcomeres space myosin, which creates the special filament, and actin, which creates the slim filament. Myosin has a long, fibrous tail and a globular head that binding to actin. The myosin head likewise binds to ATP, the source of power for cellular metabolism, and is forced for the cardiomyocytes come sustain themselves and role normally. Together, myosin and actin form myofibril filaments, the elongated, contractile threads found in muscle tissue. Cardiac muscle and skeletal muscle both save the protein myoglobin, which stores oxygen.

Cardiac muscle is adapted to be very resistant to fatigue. Cardiomyocytes have actually a large number that mitochondria, enabling constant aerobic respiration. Cardiac muscle additionally has a large blood supply loved one to the size, which provides a continuous stream the nutrients and also oxygen while providing ample remove of metabolic waste.


Cardiac Muscle: The tissue framework of cardiac muscle contains sarcomeres that room made of myofibrils with intercalated disks, that contain cardiomyocytes and also have many mitocondria.


Myocardial Thickness

The myocardium has actually variable level of thickness within the heart. Chambers the the heart with a more thick myocardium room able come pump blood with more pressure and force compared to chambers that the heart v a diluent myocardium. The myocardium is thinnest in ~ the atria, together these chambers generally fill v passive blood flow. The right ventricle myocardium is thicker than the atrial myocardium, together this muscle must pump all blood return to the heart right into the lungs for oxygenation. The myocardium is thickest in the left ventricle, as this chamber need to create considerable pressure come pump blood into the aorta and throughout systemic circulation.

The thickness the the myocardium may change in some individuals as a compensatory adaptation to disease, either thickening and ending up being stiff or becoming thinner and also flabby. Cardiac hypertrophy is a common result of hypertension (high blood pressure) in which the cells of the myocardium enlarge as an adaptive response to pumping against the greater pressure. Eventually, hypertrophy may become so severe that heart failure occurs when the love becomes therefore stiff that it deserve to no much longer pump blood. A flabby love is typically the an outcome of myocardial infections, in i beg your pardon the heart muscle i do not care so weak the it cannot effectively pump blood, which likewise leads to heart failure.


Right Ventricular Hypertrophy: If the heart adapts to become too thick, it will certainly not have the ability to pump blood as efficiently, and heart failure might occur.


Key Takeaways

Key PointsThe cardiac skeleton is composed of 4 bands of dense connective tissue, called fibrous rings, that surround the basic of the pulmonary trunk, aorta, and also mitral and also tricuspid valves.The love ‘s fibrous skeleton stops the flow of electric currents between the chambers that the heart so that it just flows with the atrioventricular (AV) bundle. This reasons a hold-up in depolarization so the the ventricles contract after castle fill with blood.The AV bundle is a bundle of electrically-connected cardiomyocytes that transmit impulses native the AV node to the apex of the heart. It is situated in the center of the cardiac skeleton.The cardiac skeleton is composed mainly the the protein collagen, a glycoprotein discovered in all connective tissues.Key Termscollagen: A glycoprotein that develops elongated fibers, usually uncovered in the extracellular procession of connective tissue.fibrous rings: Four thick bands of difficult elastic tissue that encircle the bases the the valves of the heart.

The cardiac skeleton, or fibrous skeleton of the heart, is the structure of dense connective tissue that off the atria indigenous the ventricles. The fibrous skeleton provides an important support for the heart and separates the circulation of electric impulses v the heart.

Fibrous Ring Structure


Fibrous ring of the Heart: Transverse section of the heart showing the fibrous rings bordering the valves.


The primary structure the cardiac skeleton consists of four dense bands of tough elastic tissue dubbed fibrous rings the encircle the bases that the love valves. The fibrous skeleton is composed generally of collagen, a protein found in every kind of connective organization in the human body. Over there are 4 fibrous rings:

The aortic ring encircles the aortic valve. It provides support for the aortic valve so the it is open, yet does not have backflow.The pulmonary ring encircles the pulmonary valve. Comparable to the aortic ring, it offers structural support for the pulmonary valve.The left fibrous ring encircles the bicuspid valve. This ring is the thickest and also strongest of all the fibrous rings because of the thickness that the left ventricle, which requires much more structural support than the various other chambers of the heart. It likewise surrounds the coronary arteries and AV node.The ideal fibrous ring encircles the tricuspid valve. It also surrounds the coronary arteries and AV node.

The fibrous skeleton gives a an excellent amount that structural and also functional assistance for the valves that the love by allowing them to remain open and provides a allude of attachment for the valves come the wall of the heart.

Electrical Functions

The fibrous skeleton the the love acts as an insulator for the circulation of electric current across the heart. It stop the flow of electricity in between the different chambers of the heart so that electric impulses do not flow directly in between the atria and also ventricles. The sinoatrial (SA) node lies ~ above the optimal of the heart, when the AV node is located at the center of the fibrous skeleton, the just path whereby electricity can circulation through the heart.

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This electrical separation is essential for cardiac function, because electrical impulses circulation from the optimal of the heart to the bottom the the heart. The separation allows the AV node and AV bundle to hold-up the wave of depolarization so that the atria deserve to contract and also assist in ventricular filling prior to the ventricles themselves depolarize and also contract. There is no the fibrous skeleton of the heart, the heart’s ability to pump blood would be substantially less efficient because the ventricles would contract before filled come capacity. The fibrous skeleton the the heart likewise protects versus cardiac arrhythmias.