cardiac muscle tissue (2023)

Autor: Adrian Rad BSc (Hons)•Gutachter: Franchesca Druggan BA, MSc
Last revised: November 23, 2022
Reading time: 14 minutes

cardiac muscle tissue (1)

It is very easy to overlook and take for granted a specific structure that is not readily visible in the human body. Muscles are an example of this. It's very easy to see skeletal muscle tissue, especially when you exercise.

However, cardiac and smooth muscle tissues are not as obvious compared to well-developed tissues.TrizepsÖDeltamuskel. However, you can assume that they are equally important.

This article begins by describing the general classification of muscle tissue. After that, it will focus on the features, components, and briefly the contraction ofHerzmuskelTissue.


  1. muscle tissue
  2. Characteristics
  3. components
    1. Cardiomicitos
    2. Inserted discs
    3. myofibrils and sarcomeres
    4. Cardiac conduction cells
  4. contraction
  5. clinical points
    1. Heart attack
    2. Herzhypertrophie
  6. Fuentes

+ view all

muscle tissue

Muscle tissue is one of the four basic types offabricsthat make up the human body. It consists of elongated cells arranged in parallel, which are ablesetand generate a force. Through this unique ability, muscle tissue allows the body, along with its internal parts and organs, to continuously move and adjust their shapes.

Muscle tissue is classified according to the presence or absence ofStretch markswithin the myocytes and the location of the muscle itself:

  • Striated muscle (shows crossed stripes)
    • Skeletal muscle (attached to bone)
    • Visceral striated muscles (within certain soft tissues)
    • heart muscle (within theHerz)
  • Smooth muscle (no striations)

skeletal musclesIt's a kind of voluntary muscle that acts on thebone apparatuspull theBoneand allow body movement.striated visceral muscleIt is identical to skeletal muscle but restricted to specific areas such as the tongue and upper areaesophagus, Isthroat, and the lumbar portion of the diaphragm. So let's breatheswallow, and talk.smooth muscle cellsIt is an involuntary muscle that is less structured and more easily destroyed compared to striated muscle. It is mainly part of viscera, blood vessels, erector pili and intrinsic eye muscles.

Test your knowledge of heart tissue histology with this quiz.


Cardiac muscle tissue, also known as myocardium, is a structurally and functionally unique subtype of muscle tissue found within the heart muscleHerz, which actually exhibits properties of skeletal and muscle tissue. It is strong, continuous and capablerhythmic contractionswhich are generated automatically. The contractility can be changed byVegetative Nerve Systemand hormones. In addition, this type of tissue has high metabolic, energetic, and vascular requirements.

myocardial fibersThey are long, branched cells shaped like cylinders joined at the ends, with one or two centrally located nuclei. The fibers are separated by collagenous tissue, which supports the capillary network of cardiac tissue.

Cardiac muscle myofilaments are arranged in a similar pattern to skeletal muscle, leading tohorizontal stripes. The fibers are traversed by so-called linear bandsintercalated disks. These structures have two important functions. First, they provide attachment points that impart a distinctive branching pattern to the tissue. Second, they enable the heart muscle tissue to act as asyncretism. Contractile stimuli essentially propagate from one cell to the next, resulting in a synchronous contraction of the entire tissue segment.

While most muscle cells in heart tissue physically contract, there is a special set that performs a different function. They are called hearts.conductive cellsand automatically initiate and transmit contraction impulses.



Cardiomyocytes, also known as heart muscle cells, generally contain an elongatedKernlocated in the middle, which is a characteristic feature of skeletal muscles. When examining the ultrastructure, it becomes clear that theMyofibrillenThey separate as they approach the nucleus, orbit it and reassemble into their original pattern on the other side. You can visualize the arrangement by imagining two cones connected at their tips, representing the nucleus. In fact, cell organelles are also concentrated in this cytoplasmic region around the nucleus. These include mitochondria, Golgi apparatus, granules filled with lipofuscin and glycogen.lipofuscinaIt is a red-brown pigment, often referred to as wear pigment, that gradually accumulates in heart tissue with age. It is the remnant of the contents of lysosomal cells. The cytoplasm of cardiomyocytes, calledSarcoplasm, is eosinophilic and appears as a 3D network.

Due to the high energy requirements, heart muscle tissue contains larger and more elongatedmitochondrialocated between the myofibrils. They can run the entire length of the sarcomere and contain many internal cristae. Also additionalGlycogen granulesThey are also located between myofibrils to store energy. Threads of collagenous tissue fibers along with capillaries are also present between the muscle fibers to provide tissue support and blood supply.

Inserted discs

Cardiac muscle cells are connected byintercalated disksthat coincidez-Linien. Under the light microscope they appear as lines running perpendicularly through the muscle fibers. However, when examining the ultrastructure, the discs are far from linear, as they have finger-like interlockings to maximize the contact area. The intervertebral discs also contain two compartments oriented transversely and laterally (parallel) relative to the myofibrils, resembling a staircase.

To perform their binding functions, intercalated disks contain three types of cell junctions:

  • adhesive connections (adherent tape)they are part of the transverse component and visualize the intercalated discs in hematoxylin and eosin (H&E) staining. They are responsible for connecting the ends of the myocytes into a fiber. In addition, they transmit the force of contractions from one cell to another because theactthe filaments of the terminal sarcomeres insert into these junctions.
  • Desmosomas (sticky dots)They are part of both components and reinforce adhesive bonds. They prevent myocytes from separating during contractions by anchoring intermediate filaments.
  • communication (crosses)they form part of the lateral component of the intercalated discs. They allow heart tissue to act as a syncytium by providing pathways for different ions to pass between adjacent cells, resulting in propagation of excitation and subsequent contraction.

myofibrils and sarcomeres

Sarcomerethey are the functional subunits of myofibrils and the contractile units of cardiac muscle tissue. They are arranged in a branched pattern, forming a 3D network in the cytoplasm. Sarcomeres are specific parts of myofibrils located between twoz-Linienand are responsible for the striated appearance of heart tissue. They are made up of thick and thin fibers.thick threadsThey are made up of polymerized myosin type II protein and are attached to a band called the M line, which lies in the middle of the sarcomere.thin threadsThey are formed from polymers of the protein alpha-actin and are linked to Z-lines which, together with the A-band, which corresponds to the length of the myosin filaments, are electron-rich and appear darker under the electron microscope. Bands I and H appear brighter, representing regions composed of only thin and thick filaments, respectively, but not both.

The cytoplasmic regions between the branches of the sarcomere are filled with mitochondria and are called the smooth endoplasmic reticulum (sER).sarcoplasmic crosshairs, which wraps around each myofibril. The membranous network of the sarcoplasmic reticulum is traversed by so-called structuresTubuli T, which are extensions of the sarcolemma (plasma membrane of muscle cells). They form the T-tubular system and itsLumenThey communicate directly with the extracellular space. Its course follows the Z-lines of the sarcomeres, resulting in a single T-tube for each sarcomere. The region formed by the pair of flat terminal cisternae of the sarcoplasmic reticulum and part of a T-tubule is called the T-tubuleTag.

Cardiac conduction cells

Contractions are triggered by specialized heart cells called cardiac cells and distributed throughout the heartCardiac conduction cells(they are not neurons). Together they form theconduction system of the heart. These cells form specific structures such as nodes, bundles, and conductive fibers. The initial spontaneous stimulus begins with theThe sinus nodeLocated on the wall of the right atrium at the level of the entrance to the superior vena cava. Impulses travel through the walls of the atria, causing a contraction. You will then be picked up by theatrioventricular (AV) Nodelocated above the tricuspidValvein the medial wall of the right atrium. These two ganglia are surrounded by collagenous tissue filled with capillaries and autonomic nerves. After the AV node, the impulse goes through thepackage from you, right and leftbar branches, and finally through thedes Purkinje-Systems. All three bundles stain quite pale due to their high content of glycogen granules and mitochondria. The Purkinje fibers also contain a central area that turns pale in color. Cardiac conduction cells are strictly connected only via desmosomes and gap junctions. They also don't have a T-tubule system.

As you can see, the heart is contractingspontaneous. However, despite their autonomy, the conductive cells are not isolated from thenervous system. IsArtbranch increases the pulse frequency of the nodes to the conducting system, while theparasympatheticthe branch decreases it. Since in normal situations each impulse is followed by a contraction, the rate of contraction increases or decreases.


The mechanism of contraction is similar to that of skeletal muscle. Basically, the depolarization of the sarcoplasm travels through theTubuli Tuntil reaching the sarcoplasmic reticulum. Voltage-gated channels open andCalcium-IonenThey are released into the sarcoplasm. These ions enable theMyosinjactFilaments form transverse bridges and then slide over each other(sliding thread mechanism). Excitation and contraction are transmitted to subsequent myocytes through intercalated discs and cell-to-cell junctions.

Despite the close similarities between cardiac and skeletal muscle tissue, there are several significant differences. First of all theDepolarisationof sarcoplasm lasts longer in heart tissue. Next to,calcium channelsthey are also present in the walls of the t-tubular system, rather than being strictly confined to the sarcoplasmic reticulum. The released calcium ions, in turn, bind to calcium-sensitive channels in the sarcoplasmic reticulum, resulting in a large and rapid release of more calcium ions needed for contraction.

    clinical points

    Heart attack

    As you have already seen, heart tissue requires a high and continuous supply of energy and oxygen. The oxygen supply to the heart is transported to the heart through theCoronary arteries, which are very prone to atheroma. These are abnormal deposits of fatty acids, cholesterol, and various cellular debris. As these atheromas continue to grow in size, they eventually occlude the coronary arteries, resulting in decreased tissue oxygenation. This lack of oxygen leads to a condition calledHeart attack, representing the death of heart tissue. As part of a normal physiological response, the affected area is repaired and replaced with fibrous tissue that interrupts the spread of excitatory stimuli and the heart's subsequent contraction. Such asynchronous contractions can lead to thisArrhythmias, or cardiac arrhythmias, an example is ventricular fibrillation.


    Cardiac hypertrophy means an increase in the size of cardiomyocytes. To adapt to this size, cells must assemble more sarcomeres and synthesize more mitochondria. They are also characterized by enlarged nuclei and increased protein production. Hypertrophy has several possible causes, each resulting in a specific pattern or type.

    • pressure overload hypertrophyit is often caused by high blood pressure. This is an increase in the cross-sectional area of ​​the myocyte due to the assembly of new sarcomeres parallel to the old ones. It usually affects the ventricles by increasing the thickness of their walls.
    • volume overload hypertrophyIt is caused by an abnormally high backflow of blood to the heart. It involves the formation of new sarcomeres at the end of the old ones, increasing their myocyte length rather than thickness. This type widens the ventricles and makes the heart heavier.

    Cardiac hypertrophy leads to a heart with very high oxygen and metabolic requirements, but insufficient supply due to extremely high consumption and a lack of new capillaries. In return, the workload increases andischemiapossible, eventually leading to heart failure and death.

    It is important to realize that cardiac hypertrophy is an entirely different condition than cardiac hypertrophyMyostatin-related muscle hypertrophy. The latter is rare and genetic in nature. In addition, it does not cause any medical problems for the affected person.


    All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is based on scientific literature and peer-reviewed research.Kenhub does not offer medical advice.You can learn more about our content creation and review standards by reading ourContent Quality Guidelines.


    • Ross M. H., Paulina W.:Histology: A Text and Atlas: With Correlated Molecular and Cellular Biology, Sixth Edition, Lippincott Williams & Wilkins
    • Young B., Woodford P., O'Dowd G.:Functional Histology of Wheater: A Text and Color Atlas, Sixth Edition, Churchill Livingstone Elsevier
    • Mescher Anthony L.:Basic Histology of Junqueira: Text and Atlas, 13th Edition, McGraw-Hill Education
    • Kumar V., Abbas K. A., Aster C. J.:Robbins and Cotran: Pathological Basis of Disease, Ninth Edition, Elsevier Saunders

    Cardiac muscle tissue: want to know more about it?

    Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you the best results faster.

    What is your favorite way to learn?


    "I would honestly say that Kenhub has cut my study time in half."-Continue reading.cardiac muscle tissue (2)Kim Bengochea, Universidad Regis, Denver

    © Unless otherwise stated, all content including images is the exclusive property of Kenhub GmbH and protected by German and international copyright laws. All rights reserved.
    Top Articles
    Latest Posts
    Article information

    Author: Lilliana Bartoletti

    Last Updated: 01/23/2023

    Views: 5999

    Rating: 4.2 / 5 (73 voted)

    Reviews: 80% of readers found this page helpful

    Author information

    Name: Lilliana Bartoletti

    Birthday: 1999-11-18

    Address: 58866 Tricia Spurs, North Melvinberg, HI 91346-3774

    Phone: +50616620367928

    Job: Real-Estate Liaison

    Hobby: Graffiti, Astronomy, Handball, Magic, Origami, Fashion, Foreign language learning

    Introduction: My name is Lilliana Bartoletti, I am a adventurous, pleasant, shiny, beautiful, handsome, zealous, tasty person who loves writing and wants to share my knowledge and understanding with you.