Cardiac muscular fabric: source of development, structural and functional characteristics of the fabric, features innervation and contractile activity, types of cardiomyocytes, regeneration. Muscular fabric Heart muscles is formed by smooth muscular cloth

Histogenesis and types of cells. Sources of development of cardiac transverse muscular fabric - Symmetric sections of a visceral sheet of splash in the neck part of the embryo - the so-called mioepicardial plates. Mesothelius epicardium cells are also differentiated.

In the course of histogenesis there are 3 types of cardiomyocytes:

• workers, or typical, or contractile, cardiomyocytes,
• Atypical cardiomyocytes (here include paister, conductive and transient cardiomyocytes)
• Secretor cardiomyocytes.

Working (contractile) cardiomyocytes form their chains. Crocheting, they ensure the power of reducing the entire heart muscle. Working cardiomyocytes are able to transmit control signals to each other. Sine (Paismaker) Cardiomyocytes are capable of replacing the state of relaxation in a certain rhythm. They perceive control signals from nerve fibers, in response to which they change the rhythm of contractual activity. Sine (pacemeker) cardiomyocytes transmit control signals to transient cardiomyocytes, and the last - conductive. Conductive cardiomyocytes form cell chains connected by its ends. The first cell in the chain perceives control signals from sinus cardiomyocytes and transmits them further - to other conductive cardiomyocytes. Cells, closing the chain, transmit a signal through transient cardiomyocytes workers.

Secretor cardiomyocytes perform a special function. They produce a hormone - a sodium factor, participating in the processes of regulation of urinating and in some other processes.

Correspondence cardiomyocytes have an elongated (100-150 μm) form close to cylindrical. Their ends are connected to each other, so that the cell chains make up the so-called functional fibers (up to 20 microns thick). In the field of cell contacts, so-called insert discs are formed. Cardiomyocytes can branch and form a three-dimensional network. Their surfaces are covered with a basal membrane, in which the reticular and collagen fibers are invested outside. Cardiomyocyt kernel (sometimes two) oval and lies in the central part of the cell. The core poles focuses the few organelles of the overall meaning. Myofibrillas are poorly isolated from each other, they can split. Their structure is similar to the structure of myofibrils of myiosimplast skeletal muscle fiber. From the surface of the plasmolemma, the T-tubes are directed at the Z-line level. Their membranes are brought together, in contact with the membranes with a smooth endoplasmic (i.e. sarcoplasmic) network. The loops of the latter are elongated along the surface of the Miofibrils and have lateral thickening (L-systems) forming together with T-tubes of triads or Diaps. In the cytoplasm there are inclusions of glycogen and lipids, especially many Mioglobin inclusions. The mechanism of reduction of cardiomyocytes is the same as in Miosimplast.

Cardiomyocytes are connected to each other with their end ends. Here are the so-called insert discs: these sites look like thin plates with an increase in the light microscope. In fact, the ends of the cardiomyocytes have an uneven surface, therefore the protrusions of the same cell enter the depressions of the other. The transverse sections of the ledges of neighboring cells are connected to each other interfigations and desmoms. By each desmosome, the cytoplasm is suitable for the Miofibrilla, fixing the end in the desmoplakin complex. Thus, when reducing the thrust of one cardiomyocyte is transmitted to another. The side surfaces of cardiomyocyte protrusions are combined with nexus (or slit compounds). This creates metabolic links between them and provides synchronization of abbreviations.

Possibilities of regeneration of cardiac muscle tissue. With long reinforced work (for example, under conditions of constantly increased blood pressure), working hypertrophy of cardiomyocytes occurs. Stem cells or precursor cells in cardiac muscle tissue were not detected, therefore dying cardiomyocytes (in particular, with myocardial infarction) are not restored, but are replaced by elements of the connective tissue.

Protective muscular cardiac tissue is included in the muscular heart wall (myocardium). The main histological element is cardiomyocyte. Cardiomyocytes are also present in the proximal part of the aorta and the upper hollow vein.
A. Cardiomionesis. The myoblasts occur from the cells of the splash mesoderm surrounding the endocardial tube (chapter 10 B I). After a series of mitotic divisions G, -MhO6- Lastos begin the synthesis of contractile and auxiliary proteins and through the stage of G0-myoblasts are differentiated into cardiomyocytes, acquired an elongated form; The sarcoplasma begins the assembly of myofibrils. In contrast to the cross-born muscle tissue of a skeletal type, the Cardiomionesis does not receive a cambial reserve, and all cardiomyocytes are irreversibly in the phase of the cell cycle. Specific transcription factor (CATFL / SMBP2, 600502, ILQL3.2-QL3.4 gene) is expressed only in developing and generated by myocardium.
B. Cardiomiocytes are located between the elements of loose fibrous connective tissue containing numerous blood capillaries The basin of the vascular vessels and the terminal branches of motor axons of nerve cells of the vegetative unit of the nervous system. Each myocyte has a sarchatum (basal membrane + plasmolem). There are workers, atypical and secretory cardiomyocytes.

1. Working cardiomyocytes (Fig. 7-11) - morphofunctional units of cardiac muscle tissue - have a cylindrical branching form with a diameter of about 15 microns. Cells contain miofibrillas and tanks associated with them and sarcoplasmic reticulum tube (CA2 + depot), centrally located one or two kernels. Operating cardiomyocytes using intercellular contacts (inserted discs) are combined into the so-called hearty muscle fibers - functional synts (totality of cardiomyocytes within each heart chamber).

but. Contact apparatus. Organization of Miofibrils and Sarcomers in cardiomiites are the same as in skeletal muscle fiber (see I B I, 2). The same mechanism of the interaction of thin and thick threads with a reduction (see I g 5, 6, 7).
b. Sarkopoplasmic network. CA2 + release from sarcoplasmic reticulum is regulated via Rioman Application Receptors (see also chapter 2 III A 3 B (3) (a)). Changes in the membrane potential are discovered by potential-dependent CA2 + - channels, the concentration of Ca2 + is slightly increasing in cardiomiocytes. This CA2 + activates Rioman CA2 receptors, and Ca2 * goes to cytosol (calcium-induced Mobilization Ca2 +).
in. T-tube in cardiomyocytes, in contrast to skeletal muscle fibers, pass at the z-lines level. In this regard, the T-tube contacts only one terminal tank. As a result, instead of three skeletal muscle fibers, Diases are formed.
mitochondria is located in parallel rows between the myofibrils. Their more dense clusters are observed at the level of I-disks and nuclei.


Longitudinal
plot.

Insert disk

| Erythrocyte

Complex G Oldi

Core
Endothelial
cell

. Capillary clearance

Z-line "Mitochondria-1

Basal
membrane

Miofibrils

Fig. 7-11. Work cardiomyocyte - elongated cell shape. The kernel is located centrally, near the kernel there is a Golgi complex and granules. There are numerous mitochondria between myofibrils. Insert wheels (on the insertion) serve to bonding cardiomyocytes and synchronize their abbreviation [from Hees H, SINOWATZ F (1992) and Kopf-Maierp, Merker H-J (1989))

d. Insert wheels. At the ends of contacting cardiomyocytes there are interdigate (finger-shaped protrusion and deepening). The increase in one cell is tight in the recess of the other. At the end of such a protrusion (transverse section of the inserted disk), contacts of two types are concentrated: desplaomoms and intermediate. On the side surface of the protrusion (longitudinal plot of inserted disk) there are many slot contacts (Nexus, Nexus).

1. Desmosomoms provide a mechanical clutch that prevents the discrepancy of cardiomyocytes.
2. Intermediate contacts are needed to attach thin actin yarns of the nearest sarcomer to the sarchatum of the cardiomyocyte.
3. Sloves are intercellular ion channels that allow excitation to jump from cardiomyocyte to cardiomyocyth. This circumstance is along with a conductive heart system - allows you to synchronize the simultaneous reduction in the set of cardiomyocytes in the composition of functional syntsium.

e. Atrial and ventricular myocytes are different populations of workers cardiomyocytes. In the atrial cardiomyocytes, the system of T-tubes is weaker, but in the insertion zone of insert disks is significantly more slugging contacts. Stomatricular cardiomyocytes are larger, they have a well-developed system T-tube. The contracting apparatus of the myocytes of atrial and ventricles includes various isoforms of myosin, actin and other contractile proteins.

1. Atypical cardiomyocytes. This outdated term refers to myocytes forming a conductive heart system (chapter 10 b 2 b (2)). Among them there are drivers of rhythm and conductive myocytes.

but. Rhythm drivers (pacemaker cells, pacemakers; Fig. 7-12) - a set of specialized cardiomyocytes in the form of thin fibers, surrounded by loose connective tissue. Compared to working cardiomyocytes, they have smaller sizes. The sarcoplasma contains relatively little glycogen and a small amount of myofibrils lying mainly along the periphery of the cells. These cells have rich vascularization and motor vegetative innervation. Thus, in the sinus-atrial unit, the share of connective tissue elements (including blood capillaries) is 1.5-3 times, and nerve elements (neurons and motor nerve endings) 2.5-5 times higher than in the working myocardium of the right atrium. The main property of rhythm drivers is spontaneous depolarization of the plasma membrane. Upon reaching a critical value, the potential of action spreads through the fibers of the conductive heart system and reaching workers cardiomyocytes. The main driver of the rhythm - the cells of the sinus-atrial node - generates a rhythm of 60-90 pulses per minute. Normally, the activity of other rhythm drivers is suppressed.

1. Spontaneous generation of pulses potentially inherent not only by rhythm drivers, but also all atypical, as well as working cardiomyocytes. So, in vitro all cardiomyocytes are capable of spontaneous reduction.
2. There is a hierarchy of rhythm drivers in the conductive heart system: the closer to the working myocytes, the less often spontaneous rhythm.

b. Correlation cardiomyocytes are specialized cells that perform the function of excitation from rhythm drivers. These cells form long fibers.

1. Gyze beam. Cardiomyocytes of this beam spend excite from rhythm drivers to Purkin's fibers, contain relatively long myofibrils having a spiral move; Small mitochondria and a small amount of glycogen. Cardiomyocytes of the GYSE bundle are also included in the composition of the sine-atrial and atreservantic nodes.
2. Purkin fibers. Cardiomyocytes of Purkin's fibers are the largest myocardial cells. They contain a rare disordered network of myofibrils, numerous small mitochondria, a large amount of glycogen. Cardiomyocytes of Purkin's fibers do not have T-tubes and do not form inserts. They are associated with despair and slotted contacts. The latter occupy a significant area of \u200b\u200bcontacting cells, which ensures high speed of the pulse by Purkin's fibers.

1. Secretor cardiomyocytes. In part of the atrial cardiomyocytes (especially right), the core poles are located a well-pronounced Golgi complex and secretory granules containing Atropeptin - a hormone regulating blood pressure (chapter 10 b 2 b (3)).

V. Innervation. The activities of the heart - a complex autoremore and adjustable system - has an influence of many factors, incl. Motor Vegetative

Fig. 7-12. Atypical cardiomyocytes. A - the driver of the rhythm of the sinus-atrial node;
B - Cardiomiocyte GYSE beam [from Hees N, SINOWATZ F, 1992]

innervation is parasympathetic and sympathetic. Parasympathetic innervation is carried out by terminal varicose endings of axons of a wandering nerve, and the sympathetic - endings of axons of adrenergic neurons of the cervical top, cervical medium and stars (shain-thoracic) ganglia. In the context of the idea of \u200b\u200bthe heart as a complex autoremore system, the sensitive innervation of the heart (both vegetative and somatic) should be considered as part of the regulation system
blood flow.

1. Music vegetative innervation. The effects of parasympathetic and sympathetic innervations are implemented accordingly muscarinic cholinergic and

adrenergic plasmolemma receptors of different heart cells (cardiomyocytes working and especially atypical, intracardiac neurons of their own nervous apparatus). There are many pharmacological preparations that have a direct action on the named receptors. Thus, norepinephrine, adrenaline and other adrenergic drugs, depending on the effect on A- and P-adrenoreceptors, are divided into activating (adrenomimetics) and blocking (adrenoblokasters) agents. M-cholinoreceptors also have similar classes of preparations (cholinomimetics and cholinoblocators).
but. The activation of sympathetic nerves increases the frequency of spontaneous depolarization membranes of rhythm drivers, facilitates the pulse in Purkinier fibers and increases the frequency and strength of the reduction of typical cardiomyocytes.
b. Parasympathetic influences, on the contrary, reduce the frequency of generation of pulses by PaisMakers, reduce the rate of pulse in Purkinier fibers and reduce the frequency of reducing operating cardiomyocytes.

1. Sensitive innervation

but. Spinal. Peripheral processes of sensitive neurons of spinal nodes form free and encapsulated nerve endings.
b. Specialized sensory structures of the cardiovascular system are considered in chapter 10.

1. Introsertive vegetative neurons (motor and sensitive) can form local neuroregulatory mechanisms.
2. Myth cells. A small intense fluorescent cell is a variety of neurons, it was found in almost all vegetative ganglia. This is a small (diameter of 10-20 μm) and the irresponsive (or with a small number of processes) of the cell, in the cytoplasm contains a plurality of large granular bubbles with a diameter of 50-200 nm with catecholamines. The granular endoplasmic network is developed weakly and does not form clusters similar to the Nissl Tales.

Regeneration. For ischemic Disease Hearts (IBS), atherosclerosis coronary vessels, heart failure of different etiology (including arterial hypertension, myocardial infarction) there are pathological changes in cardiomyocytes, including their death.

1. Reparative regeneration of cardiomyocytes is impossible, because They are located in the phase G0 of the cell cycle, and the G1-myoblasts in myocardium are absent similar to satellite satellite cells. For this reason, a connecting circuit with all the consecutive consequences (heart failure) for conducting and contractile functions of myocardium, as well as for the condition of blood flow, is formed on the site of the dead cardiomyocytes.
2. Heart failure - a violation of the ability of the heart to ensure the blood supply to the organs in accordance with their metabolic needs.

but. Causes of heart failure are a decrease in contractility, an increase in the disposage, changes in preload.
Reduced contractile ability
(a) Myocardial infarction - necrosis of the heart muscle site with loss of its ability to reduce. The replacement of the affected part of the ventricular wall with a connecting tissue leads to a decrease in the functional properties of myocardium. With damage to a significant part of myocardium, heart failure is developing.
(b) Congenital and acquired malformations of the heart lead to overload of the cavities of the heart pressure or the volume with the development of heart failure.
(c) arterial hypertension. Many patients with hypertensive disease or symptomatic hypertension suffer from blood circulation deficiency. The reduction in the contractile ability of myocardium is characteristic of a rack of heavy hypertension, which quickly leads to the development of heart failure.
(d) Cardiomyopathy Toxic (alcohol, cobalt, catecholamines, doxoroscin), infectious, so-called. Collagen diseases, restrictive (amyloid and sarcoidosis, idiopathic).
b. Compensatory mechanisms in heart failure. Phenomena arising from the law of Frank Starling, incl. Myocardium hypertrophy, dilatation of the left ventricle, peripheral vasoconstriction due to the emission of catecholamines, activation of the renin-angiotensin- [aldosterone] and vasopressin, reprogramming the synthesis of mosinos in cardiomyocytes, an increase in the secretion of atropeptine, - compensatory mechanisms that support a positive inotropic effect. However, sooner or later myocardium loses the ability to provide a normal cardiac output.

1. Hypertrophy of cardiomyocytes in the form of an increase in cell mass (including their polyptloidization) - a compensatory mechanism that adapts the heart to functioning in pathological situations.
2. Reprogramming the synthesis of mosinov in cardiomyocytes occurs with an increase in the OPS to maintain cardiac output, as well as under the influence of increased blood content in T3 and T4 with thyrotoxicosis. There are several genes for lightweight and heavy chains of cardiac alone, differing in the activity of the ATPase, and therefore the duration of the working cycle (see ig 6) and the developed voltage. Reprogramming of mosins (like other contractile proteins) provides cardiac output at an acceptable level until the capabilities of this adaptive mechanism are exhausted. With the exhaustion of these possibilities, heart failure is developing - left-sided (left ventricular hypertrophy, followed by its dilatation and dystrophic changes), right-sided (stagnation in a small circulation circle).
3. Renin-angiotensin- [aldosterone], Vasopressin - a powerful system of vase-constructions.
4. Peripheral vasoconstriction due to the emission of catecholamines.
5. Atropeptin is a hormone that realizes vasodilation.

Cardiac muscular fabric Forms middle shell (myocardium) atrial and ventricles of the heart and is represented by two varieties of working and conductive.

Working muscular fabric Consists of cardiomyocyte cells, the most important feature of which is the presence of perfect contact zones. Connecting with each other, the end ends, they form the structure similar to the muscle fiber. On the side surfaces, cardiomyocytes have branches. Connecting ends with the branches of neighboring cardiomyocytes, they form anastomosis. The boundaries between the ends of the adjacent cardiomyocytes are inserted discs with straight or stepped circuits. In the light microscope, they have the type of transverse dark strips. Using inserts and anastomoses, a single structural and functional contracting system is formed.

In electron microscopy, it was revealed that in the field of inserted disks, one cell is in the other finance protrusions, on the side surfaces of which are desmosomoms, which ensures high adhesion strength. At the ends of the finance protrusions, sling was found through which the nerve impulses quickly propagate from the cell to the cell without the participation of the mediator synchronizing the reduction of cardiomyocytes.

Cardiac myocytes are single-core, sometimes dual-core cells. The kernels are located in the center, in contrast to skeletal muscle fibers. In the near-door zone there are components of the Golgi, Mitochondria, Lizosomes, Glycogen Granules.

The contracting apparatus of myocytes, as well as in skeletal muscle tissue, consists of myofibrils that occupy the peripheral part of the cell. Their diameter from 1 to 3 microns.

Myofibrils are similar to the myofibrils of skeletal muscle tissue. They are also constructed from anisotropic and isotropic disks, which also causes transverse allocations.

The cardiomyocyte plasmolm at the level of the Z-strips is infant into the depth of the cytoplasm, forming transverse tubes, differing from skeletal muscle tissue with a large diameter and the presence of a basal membrane that covers them outside, as well as sarchatim. The depolarization waves, which come inside the cardiac myocytes with plasmolemma, cause the slip of actin miosin (Protofibril) in relation to myosinov, causing the reduction as in skeletal muscle tissue.

T-tubes in cardiac operating cardiomyocytes form Diaps, that is, connected with the tanks of the sarcoplasmic network only on the one hand. Working cardiomyocytes have a length of 50-120 μm, a width of 15-20 microns. The number of myofibrils in them is less than in muscle fibers.

Cardiac muscular fabric contains a lot of myoglobin, so dark red. In myocytes there are many mitochondria and glycogen, i.e.: The energy of the heart muscle tissue is obtained during the decay of ATP, and as a result of glycolysis. Thus, the heart muscle works continuously all his life due to powerful energy equipment.

The intensity and frequency of abbreviations of the heart muscle are regulated by nerve impulses.

In embryogenesis, working muscle tissue develops from special sections of visceral leaflet of non-elected mesoderm (splash). In the formed working muscle tissue of the heart there are no cambial cells (miosatellites), so when damaged myocardium in the injured zone, the cardiomyocytes die and fibrous connecting tissue develops at the injury.

Conductive muscular heart fabric It is located as part of a complex of formations of the sinus-atrial node, located at the mouth of the cranical hollow vein, the atrocadic assembly, lying in the interdestrian partition, the atrocadic trunk (Gis beam) and its branches under the endocardium of the interventricular partition and in the connecting beds Myocardium.

All components of this system are formed by atypical cells specialized either on the production of pulse spreading throughout the heart and causing a reduction in its departments in the required sequence (rhythm) or in a pulse to working cardiomyocytes.

For atypical myocytes, a significant amount of cytoplasm is characterized, in which few myofibrils occupy the peripheral part and do not have a parallel orientation, as a result of which these cells are not characterized by transverse aperture. The kernels are located in the center of the cells. The cytoplasm is rich in glycogen, but there are few mitochondria in it, which indicates intensive glycolize and low-level aerobic oxidation. Therefore, the cells of the conductive system are more resistant to oxygen starvation than contracting cardiomyocytes.

As part of the sinus-atrial node atypical cardiomyocytes smaller, rounded shape. Nervous impulses are formed in them and they relate to the main rhythm drivers. The myocytes of the atrocarditricular node is somewhat larger, and the fibers of the Gis beam (Purkinier fibers) consist of large rounded and oval myocytes with an eccentric nucleus. The diameter of them is 2-3 times more than workers cardiomyocytes. The electron microscopically revealed that in atypical miacites weak the sarcoplasmic network, there is no system T-tube. Cells are connected not only by ends, but also side surfaces. Insert discs are arranged easier and do not contain finger-shaped connections, despair and nexus.

Muscular fabrics Combines the ability to reduce.

Particularities of the structure: a contractor, which occupies a significant part in the cytoplasm structural elements muscle tissue and consisting of actin and mosic filaments that form special purpose organelles - miofibrils .

Classification of muscular fabrics

1. Morphofunctional classification:

1) Transverse, or exhausted muscular fabric: skeletal and heartfelt;

2) Unigenous muscular tissue: smooth.

2. Histogenetic classification (depending on sources of development):

1) Somatic type (from somitov's miotomites) - skeletal muscle tissue (transverse);

2) Children's type (from the mioepcardial plate of visceral sheet of splash) - heart muscle tissue (transverse);

3) Mesenchymal type (develops from mesenchym) - smooth muscular fabric;

4) From the skin ectoderma and proportal plate - Moepithelial cells of hotels (smooth myocytes);

5) Neural Origin (from a nervous tube) - Mioneral cells (smooth muscles, narrowing and expanding pupil).

Muscular fabric functions: Moving the body or its parts in space.

Skeletal muscular fabric

Occaped (cross-striped) muscular fabric It makes up to 40% of the mass of an adult, part of skeletal muscles, muscles of the language, larynx, etc. refer to arbitrary muscles, since their reductions are subject to the will of a person. It is these muscles that are involved in sports.

Histogenesis. Skeletal muscle tissue develops from the cells of the Miotomes of myoblasts. There are head, cervical, chest, lumbar, sacral Miotoma. They grow up in the dozal and ventral directions. The branches of the spinal nerves will grow early in them. Part of the myoblasts are differentiated in place (form an autochthonous musculature), and others from 3 weeks of intrauterine development migrate into the mesenchym and, merging with each other, form muscular tubes (Mitubs) With large centrally oriented nuclei. In the Miotubes there is differentiation of special organel miofibrils. Initially, they are located under the plasmolemma, and then fill most of the Miotuba. The kernels are shifted to the periphery. Cell centers and microtubules disappear, the pulps is significantly reduced. Such a multi-core structure is called symplast , and for muscle tissue - miosimplast . Some myoblasts are differentiated into miosatelitical acids, which are located on the surface of myosimplests and subsequently take part in the regeneration of muscle tissue.

Skeletal muscle tissue

Consider the structure of muscle tissue at several levels of living organization: at the organ level (muscle as an organ), on the tissue (directly muscle tissue), on the cell (the structure of muscular fiber), on the subcellular (structure of myofibrils) and at the molecular level (the structure of actin and mosinic threads).

On Carint:

1 - Muscle icy (organ level), 2 - transverse muscle cut (fabric level) - muscle fibers, between which RVST: 3 - endomisia, 4 - nervous fiber, 5 - blood vessel; 6 - cross-section of muscle fiber (cellular level): 7 - muscle fiber kernels - symplast, 8 - mitochondria between myofibrils, blue - sarcoplasmic reticulum; 9 - cross-section Miofibrillas (subcellular level): 10 - Thin Actin Threads, 11 - Thick Mosic Threads, 12 - Heads of Thick Mosic Threads.

1) Organ Level: Building muscles as an organ.

The skeletal muscle consists of beams of muscle fibers connected together by the system of connective tissue components. Endomisia- Strikes RVST between muscle fibers where blood vessels pass, nerve endings . Perimisia - surrounds 10-100 bunches of muscle fibers. Epimizius - The outer sheath of the muscles is represented by a dense fibrous cloth.

2) fabric level: structure muscle tissue.

The structural and functional unit of skeletal transverse (acheutable) muscle tissue is muscular fiber - cylindrical form formation with a diameter of 50 microns and a length of 1 to 10-20 cm. Muscular fiber consists of 1) miosimplest (look at it above, the structure is lower), 2) small cambial cells - miosatelitocyteMoving to the surface of the Miosimplast and are located in the recesses of its plasmolemma, 3) of the basal membrane, which is covered by plasmolem. The complex of plasmolem and the basal membrane is called sarchatimma. For muscle fiber, the transverse allocation is characterized, the kernel is shifted to the periphery. Between muscle fibers - Strusting RVST (endomisia).

3) Cellular level: structure muscular fiber (miosimplast).

The term "muscular fiber" implies Miosimplast, since myiosimplast provides a reduction function, myosatellocytes participate only in regeneration.

Miosimplast, like a cell, consists of 3 components: nuclei (or rather than nuclei), cytoplasm (sarcoplasma) and plasmolemma (which is covered with a basal membrane and is called Sarcolmma). Almost the entire volume of the cytoplasm is filled with Miofibrils - special purpose orgellary, general purpose organelles: GREPS, AEPS, Mitochondria, Golgi complex, lysosomes, and the kernel are shifted to the periphery of the fiber.

In muscle fiber (miosimplast) differ functional devices: membrane, fibrillar (contractile) and trophic.

Trophic apparatusincludes kernels, sarcoplasm and cytoplasmic organelles: mitochondria (energy synthesis), GREPS and Golgi complex (protein synthesis - structural components Miofibrils), lysosomes (phagocytosis of worn-out structural components of fiber).

Membrane apparatus: Each muscular fiber is covered with a sarchatma, where the outer basal membrane is distinguished (under the basal membrane), which forms pensions ( T.-Pube). To each T.-Pube is adjacent two tanks triad: Two L.- Hubles (Tsters of AEPS) and one T.-Pube (plasmolm piercing). In the tanks of the AEPS concentrate SA 2+ required while reducing. Miosatellitocytes arrive outside the plasmolemma. In case of damage to the basal membrane, the mitotic cycle of myosatellitocytes is launched.

Fibrillar apparatusThe long part of the cytoplasm of the allocated fibers occupy special purpose organelles - miofibrillas, are oriented longitudinally, providing contractile function of tissue.

4) Sub-cell level: Building miofibrils.

In the study of muscle fibers and myofibrils under a light microscope, there is an alternation of dark and light sections in them. Dark discs are distinguished by double bempraine and are called anisotropic disks, or BUT- disks. Light discs do not possess double bempraine and are called isotropic, or I.-Disc.

In the middle of the disk BUT There is a brighter area - N.-zone, where only thick threads of myozin protein are contained. In the middle N.-sons (means BUT-dy) stands out darker M.-Linia consisting of Miomesin (needed to assemble thick threads and fixing them with reduction). In the middle of the disk I. Located dense line Z.which is built of protein fibrillar molecules. Z.-Ronia is connected to neighboring myofibrils using desphan protein, and therefore all these lines and drives of neighboring myofibrill coincide and a picture of the transverse perverse of the muscular fiber is created.

Structural unit Myofibrillas is Sarcomer (S.) — this is a bunch of myofilaments prisoner between two Z.-lines. Myofibrill consists of a variety of sarcomers. The formula describing the structure of the Sarcomer:

S. = Z. 1 + 1/2 I. 1 + BUT + 1/2 I. 2 + Z. 2

5) Molecular level: Building aktinov and mosinova Filaments .

Under electron microscope Myofibrillas represent aggregates of thick, or mosinova, and thin, or aktinov, filaments. Between thick filaments are thin filaments (diameter 7-8 nm).

Thick filaments, or alone threads,(diameter 14 nm, length 1500 nm, the distance between them is 20-30 nm) consist of molecules of the protein of myosin, which is the most important contractile protein of the muscle, 300-400 molecules of myosis in each thread. Miosis molecule is a hexamer consisting of two heavy and four light chains. Heavy chains are two spiral twisted polypeptide threads. They carry spherical heads at their ends. There is a hinge section between the head and heavy chain, with which the head can change its configuration. In the head area - light chains (two each). Misepes molecules are laid in thick threads in such a way that their heads are turned outward, speaking over the surface of thick threads, and heavy chains form a thick thread rod.

Myosin has ATP-azna activity: released energy is used for muscle contraction.

Thin filaments, or actin threads, (Diameter 7-8 nm), formed by three proteins: actin, troponin and tropomosin. The main most protein is Aktin, which forms a spiral. Tropomyozin molecules are located in the groove of this helix, troponin molecules are located along the spiral.

Thick threads occupy the central part of Sarcomer - BUT-disk, thin occupy I.- disks and partially included between thick myophilaments. N.- It consists of thick threads.

At rest interaction of thin and thick threads (myofilaments)it is impossible, because Myozin-binding plots of actin are blocked by troponin and tropomosin. With a high concentration of calcium ions, conformational changes in tropomyosine lead to unlocking the myozin-binding sections of actin molecules.

Muscular fiber motor innervation. Each muscular fiber has its own innervation apparatus (motor plaque) and is surrounded by a network of hemokapillars located in the adjacent RVST. This complex is called mion. A group of muscle fibers that are innervated by one motoryone called nervous muscular unit. Muscular fibers in this case can be placed nearby (one nervous end can control from one to dozen muscle fibers).

When the nerve impulses arrives in the axon of motor neurons occurs reduction of muscle fiber.

Reduced muscle

When reducing muscle fibers are shortened, but the length of the actin and mosic filaments in the myofibrils does not change, and their movement occurs relative to each other: myosine threads are moving into space between Aktinov A, Aktinov - Between myosinov. As a result, the width is reduced I.-disc H.-poligas and decreases the length of the sarcomer; width BUT-Disc does not change.

Sarcomer formula with full reduction: S. = Z. 1 + BUT+ Z. 2

Molecular Muscular Reduction Mechanism

1. Passage of a nerve impulse through neuro-muscular synaps and depolarization of muscle fiber plasmolem;

2. The depolarization wave passes by T.- pipes (plasmolem piercing) to L.-Tubeons (sarcoplasmic reticulum tanks);

3. Opening of calcium channels in sarcoplasmic reticulum and ion yields SA 2+ in sarcoplasma;

4. Calcium diffuses to thin threads of the sarcomer, binds to troponin C, leading to conformational changes in tropomyosis and freeing active centers for the binding of myosin and actin;

5. The interaction of myosine heads with active centers on the actin molecule with the formation of actino-mosic "bridges";

6. The myosine heads "walk" on the actin, forming new connections of actin and myosin during the movement, while actin threads are tightened into the space between myosine threads to M.-lini, bringing away two Z.-lini;

7. Relaxation: SA 2+ -atf-az sarpoplasmic reticulum pumps SA 2+ from sarcoplasma in tanks. In sarcoplasm concentration SA 2+ becomes low. Troponin's bonds are broken FROM With calcium, tropomyosis closes the myosin-binding plots of thin threads and prevents them from interacting with myosin.

Each movement of the MIOSIN head (accession to the actine and disconnection) is accompanied by the cost of ATP.

Sensitive innervation (neuromuscular spindle). Intrafusal muscle fibers together with sensitive nerve endings form neuromuscular spindles, which are a skeletal muscle receptors. Outside formed a capsule spindle. When reducing cross-striped (running) muscle fibers, the tension of the connecting and woven capsule is changed and the tone of intraphus (arranged under the capsule) of muscle fibers changes accordingly. A nervous impulse is formed. With excessive stretching, the muscles arises a feeling of pain.

Classification and types of muscle fibers

1. By the nature of the reduction: phase and tonicmuscular fibers. Phase are able to carry out rapid abbreviations, but cannot hold the achieved shortening level. Tonic muscle fibers (slow) provide maintaining static voltage or tone, which plays a role in maintaining a certain position of the body in space.

2. According to biochemical features and color Highlight red and white muscular fibers. The color of the muscles is due to the degree of vascularization and the content of myoglobin. The characteristic feature of the red muscular fibers is the presence of numerous mitochondria, the chains of which are located between the myofibrils. In white muscle fibers, mitochondria are smaller and they are uniformly in the sarcoplasm of muscle fiber.

3. By type of oxidative exchange : oxidative, glycolithic and intermediate. The identification of muscle fibers is based on the identification of the activity of the enzyme succinate dehydrogenase (SDH), which is a marker for mitochondria and the Krebs cycle. The activity of this enzyme indicates the tension of energy metabolism. Muscular fibers are isolated BUT-Type (glycolithic) with low SDG activity, FROM-Type (oxidative) with high activity ADH. Muscular fibers IN-Type occupy an intermediate position. Muscular fiber transition from BUT-Type B. FROM-Type lakes changes from anaerobic glycolysis to metabolism, depending on oxygen.

Sprinter (athletes, when fast short-range reduction, bodybuilders need) workout and nutrition is aimed at the development of glycolytic, fast, white muscular volccasses: there are many glycogen reserves and energy produced mainly by analombic way (white meat in chicken). Styers (athletes - Marathonians, in those sports where endurance is needed) oxidative, slow, red fibers in muscles are dominated - there are many mitochondria in them for aerobic glycolysis, blood vessels (needed oxygen).

4. In the running muscles, two types of muscle fibers distinguish: extrafusalwho prevail and cause actually the contractile function of the muscles and intrafusalincluded in propriceceptors - neuromuscular spindles.

The factors defining the structure and function of the skeletal muscle are the effect of nervous tissue, hormonal effect, muscle location, level of vascularization and motor activity.

Cardiac muscular fabric

Heart muscular fabrics in the muscular shell of the heart (myocardium) and in the mouths of the large vessels associated with it. It has a cellular type of structure and the main functional property is the ability to spontaneous rhythmic abbreviations (involuntary reductions).

It develops from a mioepcardial plate (visceral leaflet of mesoderm in the cervical leaflet), the cells of which are multiplied by mitosis, and then differentiate. The cells appear in the cells, which further form myofibrils.

Structure. Structural unit of cardiac muscular fabric - cell cardiomiocyte.Between the cells there are layers of RVST with blood vessels and nerves.

Types of cardiomyocyte : 1) typical (workers, contractile), 2) atypical(conductive), 3) secretory.

Typical cardiomyocytes

Typical (workers, contractile) cardiomyocytes - Cylindrical cells, up to 100-150 μm long and 10-20 μm diameters. Cardiomyocytes form the bulk of myocardium, connected to each other in the chain bases of cylinders. These zones are called inserted discsin which the desmotomomal contacts and nexus (slut-like contacts) are distinguished. Desmosomoms provide mechanical clutch, which prevents the discrepancy of cardiomyocytes. Slim contacts contribute to the transfer of reduction from one cardiomyocyte to another.

Each cardiomyocyte contain one or two nuclei, sarcoplasm and plasmolem, surrounded by the basal membrane. There are functional devices, the same as in the muscular fiber: membrane, fibrillar (contractile), trophic,as well as Energy.

Trophic apparatus includes the kernel, sarcoplasma and cytoplasmic organelles: GREPS and the Golges complex (protein synthesis - structural components of myofibrils), lysosomes (phagocytosis of the structural components of the cell). Cardiomyocytes, like the olokna skeletal muscle tissue, are characterized by the presence of iron-containing oxygen-binding pigment of myoglobin, which gives them red and similar in structure and function with hemoglobin erythrocytes in their sarcoplasma.

Energy apparatus Presented by mitochondria and inclusions, whose splitting ensures energy. Mitochondria is numerous, lie between fibrils, in the poles of the nucleus and under the Sarcollam. The energy required by cardiomyocytes is obtained by splitting: 1) the main energy substrate of these cells - fatty acidswho are deposited in the form of triglycerides in lipid drops; 2) glycogen in granules located between fibrils.

Membrane apparatus : Each cell is covered with a shell consisting of a plasmolem complex and basal membrane. The shell forms fusion ( T.-Pube). To each T.-Tube is adjacent one tank (unlike muscle fiber - 2 tanks) sarpoplasmatic reticuluma (modified AEPS), forming dida: One L.-buchka (tank AEPS) and one T.-Pube (plasmolm piercing). In the tanks of the AEPS ions SA 2+ accumulate not as actively as in muscle fibers.

Fibrillar (contractile) apparatus Cardiomyocyt's large part of the Cardiomiocyt cytoplasma is occupied by special purpose organelles - miofibrillas, are oriented longitudinally and located along the periphery cells. The coding apparatus of workers cardiomyocytes with skeletal muscle fibers. When relaxing, calcium ions are highlighted in a sarcoplasma at a low rate, which ensures automatism and frequent cuts of cardiomyocytes. T.-brubs wide and form Diaps (one T.-Pube and one network tank) that converge in the area Z.-Line.

Cardiomyocytes, binding to inserted discs, form contractile complexes, which contribute to the synchronization of the reduction, side anastomoses are formed between cardiomyocytes of adjacent contractile complexes.

Function of typical cardiomyocyte: Ensuring the strength of reduction of the heart muscle.

Conductive (atypical) cardiomyocytes have the ability to generate and rapid electrical impulses. They form nodes and bundles of the conductive heart system and are separated into several subtypes: PaceMekers (in the synoatrile node), transitional (in an atrio-ventricular node) and a beam cells of His and fibers Purkinje. Cardiomyocytes are characterized by the weak development of the contractile apparatus, light cytoplasm and large nuclei. There are no T-tubes and transverse aperture in cells, since myofibrils are located disordered.

Function atypical cardiomyocyte - generation of pulses and transmission to working cardiomyocytes, providing an automatism of myocardial reduction.

Secretor cardiomyocytes

Secretory cardiomyocyte in atriums, mainly in the right; Characterized by the processful shape and weak development of the contractile apparatus. In the cytoplism, near the core poles - secretory granules containing sitting factor, or atropeptin (hormone, regulating blood pressure). The hormone causes the loss of sodium and water with the urine, the extension of the vessels, a decrease in pressure, the oppression of the secretion of aldosterone, cortisol, vasopressin.

Function of secretory cardiomyocyte: endocrine.

Cardiomyocyte regeneration. For cardiomyocytes, only intracellular regeneration is characteristic. Cardiomyocytes are not capable of dividing, they have no cambial cells.

Smooth muscular fabric

Smooth muscular fabric forms the walls of the inner hollow organs, vessels; It is characterized by the lack of a allocated, involuntary abbreviations. Innervation is carried out by the vegetative nervous system.

Structural and functional unit of an inexhariced smooth muscle tissue - smooth muscular cell (MMC), or smooth myocyte. Cells have a spit-shaped form with a length of 20-1000 μm and a thickness of 2 to 20 microns. In the cell of the cells have an elongated process.

Smooth myocyt

The smooth myocyte consists of a nuclear-shaped kernel located in the center of the nucleus, cytoplasm with organelles and sarchatimms (plasmolem complex and basal membrane). In the cytoplasm at the Poles there is a Golgi complex, many mitochondria, ribosomes, and a sarcoplasmic reticulum is developed. Miofilaments are located space or along the longitudinal axis. In MMC, Aktinovy \u200b\u200band myosin filaments do not form myofibrils. Actin threads are larger and they are attached to dense tales, which are formed by special crosslinking proteins. Next to the actin threads are myosin monomers (micromyosis). Possessing different lengths, they are much shorter than thin threads.

Reducing smooth muscle cells It is carried out in the interaction of actin filaments and myosin. The signal running through the nervous fibers causes the mediator allocation, which changes the state of the plasmolemma. It forms flask-shaped phenomenon (Cavaoma), where calcium ions are concentrated. The reduction of the MMC is induced by the influx of calcium ions in cytooplasm: Cavools are packed and together with calcium ions fall into the cell. This leads to the polymerization of myosin and interacting it with actin. Actin threads and dense calves come closer, the force is transmitted to Sarchatum and the MMC is shortened. Myosin in smooth myocytes is able to interact with actin only after phosphorylation of its light chains with a special enzyme - a kinase of light chains. After stopping the calcium ion signals, Caveolas leave; Myozic depolarizes, loses affinity for actin. As a result, complexes of myofilaments are disintegrated; Reduction stops.

Special types of muscle cells

Moepithelial cells Exterma derivatives are derived, do not have allocated. The secretory departments and output duct glands (salivary, dairy, tear) are surrounded. With iron cells, they are associated with desmosomes. Reducing, contribute to the allocation of the secret. In the terminal (secretory) departments, the shape of the cells of the outflow, star. The core in the center, in the cytoplasm, mainly in the process of localized myophilaments that form a contractile device. In these cells there are cytokheratin intermediate filaments, which emphasizes their similarity with epithelocytes.

Mioneral cells they develop from the cells of the outer layer of the eye gland and form the muscle, the narrowing pupil and the muscle expanding the pupil. According to the structure, the first muscle is similar to Menchima Museum. The muscle that expanding the pupil is formed by the cells of the cells are located radially, and the poison-containing part of the cell is between the pigment epithelium and the stroma iris.

Myofibroblasts refer to loose connective tissue and are modified fibroblasts. They show the properties of fibroblasts (the intercellular substance synthesize) and smooth myocytes (have pronounced contracting properties). As a variant of these cells can be considered mioid cells As part of the walls of the convoluted seed tuber of the egg and the ovar ovarian follicle layer. When healing wounds, part of fibroblasts synthesize smooth muscle actines and mosins. Myofibroblasts ensure that the edges of the wound are tightened.

Endocrine smooth myocytes - These are modified MMC, representing the main component of the yukstaglomelar kidney apparatus. They are in the wall arteriole of the renal body, have a well-developed synthetic apparatus and reduced contractile. The enzyme renin produced in the granules and the exocytosis mechanism falling into the blood.

Regeneration of smooth muscle tissue.Smooth myocytes are characterized by intracellular regeneration. With an increase in the functional load, the hyperrophy of myocytes and in some organs hyperplasia (cellular regeneration) occurs. So, during pregnancy, smooth muscle cells of the uterus can increase 300 times.

Muscular fabrics.

Muscular fabrics - These are a different fabric by origin and structure, but similar to ability to reduce.

Morphofunctional characteristic of muscular fabric:

1. Ability to reduce.

2. Muscle has a reduction in the expense of special organelle - miofibrilliFormed by the threads of a contractile protein, actin and myosein.

3. The sarcoplasm contains the inclusion of glycogen, lipids and mioglobinwhich binds oxygen on himself. General purpose organides are poorly developed, only EPS and mitochondria are well developed, which is located in the chain between myofibrils.

Functions:

1. Movement of the body and its parts in space;

2. Muscles give the shape of the body;

Classification

1. Morphofunctional:

A) smooth,

B) transverse (skeletal, cardiac).

2. Genetic (chlopin)

Smooth muscular fabric Develops from 3 sources:

BUT) from Mezenhima - Muscular cloth forming the shell internal organs and vessel walls.

B) from Etoderma - Myepithelocytes - cells with ability to reduce, have a star form, in the form of baskets cover end departments and small output ducts of ectodermal glands. With its reduction, contribute to the allocation of the secret.

IN) neural origin - These are muscles of narrowing and expanding pupil (believe that they are developing from neuroglia).

Cross-resistant muscular fabric Develops from 2 sources:

BUT) from Miotomskeletal fabrics are laid.

B) from myoepicardial plates visceral leaf of splashnotoma In the cervical embryo, heart muscular fabric is laid.

Smooth muscular fabric

Histogenesis. Mesenchym cells are differentiated into the myocytes of which are formed.

Structural unit smooth muscle tissue is myocyt, and the structural and functional unit - floxt of smooth muscle cells.

Myocyt - Verena-shaped cell. The size of 2x8 microns during pregnancy increases to 500 microns and acquires a star form. The kernel shameful when the cage is reduced, the kernel bends or spirally twisted. Organelles of the total meaning are poorly developed (with the exception of mitochondria) and are located about the core poles. In cytoplasm - special organelles - miofibrils (represented by thefts of actin and myozin). Night actin form a three-dimensional network that is attached to the plasmolem of myocytes with special crosslinking proteins (Vinculin et al.), which are visible on micrographs as dense Tales (consist of alpha - actinine). Thread Mozin In a relaxed state of depolymerized, and when reduced, polymerization occurs, while they with actin threads forms an actinomyosine complex. Actin's plasmolem associated with its reducing threads, as a result of this, the cell is shortened and thickened. In addition to the reduction, calcium ions are in kaveylah formed by prying the cytlemma. Myocyte over plasmolemma is covered with a basal membrane, into which fibers of loose connective tissue with vessels and nerves forming endomisium. Here are the terminals of nerve fibers, ending not directly on myocytes, but between them. The mediator distinguished from them through the nexus (between cells) is transmitted immediately into several cells, which leads to a reduction in their entire formation.

Regeneration of Smooth Muscular Fabricmay go 3 ways:

1.compensator hypertrophy (increase the size of the cell),

2. Mitotic division of myocytes,

3. Increase in the number of myofibroblasts.

Transversely striped muscular fabric

Skeletal.

Histogenesis. Develops from Mesoderm Miotomes. In the development of the skeletal muscular stage, the following stages are distinguished:

1. myoblastic Stage - Cells of miotomes are loosened, with one part of the cells remain in place and participates in the formation of autochon muscle tissue, and the other part of the cells migrates into the places of future muscle bookmarks. In this case, the cells are differentiated in 2 directions: 1) myoblasts who are mothotically divided and 2) miosatellite.

2. formation of muscular tubes (miotub) - myoblasts merge among themselves and form symplast. Then, the symplast is formed by myofibrils located along the periphery, and the kernels in the center, resulting in mitubs or muscle tubes.

3. the formation of myosimplast - As a result of the far differentiation of the Mitubs turn into miosimplastAt the same time, the kernels are shifted to the perfigine, and the myofibrils are in the center and take an ordered location, which corresponds to the formation of muscle fiber. Miosatellite They are located on the surface of myosimplests and remain unoccupied. Correct kabij skeletal muscle tissue. Due to them, there is a regeneration of muscle fiber.

The structural unit of skeletal muscle tissue is muscular fiber, and structural and functional - mion. Muscular fiber - This is a myiosimplastic size reaching up to several cm and containing up to several tens of thousands of nuclei located along the periphery. In the center of the muscular fiber is up to two thousand bundles of myofibrils. Mion - It is muscle fiber, surrounded by a connective tissue with vessels and nerves.

Five devices distinguish fibers:

1. Trophic apparatus;

2. Contractor;

3. Specific membrane apparatus;

4. Support device;

5. Nervous apparatus.

1. TrophicAption represented by nuclei and organelles of the general meaning. The cores are located along the periphery of the fiber and have an extended shape, the borders of the muscle fiber are not expressed. There is a common organoid organoids (agranular EPS, Sarkosoma (Mitochondria), granular EPS is developed worse, poorly developed lysosomes, usually, they are located in the core poles) and special meaning (myofibrils).

2. Cutting machine – miofibrils (from 200 to 2500). They go parallel to each other longitudinally, optically inhomogeneous. Each myofibrill has dark and bright areas (discs). Dark discs are located opposite the dark, and bright opposite the light disks, therefore the pattern of transverse allocated fibers is created.

Threads of the contracting protein - mozin Thick and place one under the other, forming a disk A (anisotropic), which will flash M-line (mesophragm) consisting of a protein of a miomizin. Thin Nights aktin Also located one under the other, forming a light disk I (isotropic). It does not have a double bempraine, unlike the disk A. Nightin Aktin at some distance among the threads of myosin. The area of \u200b\u200bthe disk A, formed only by the threads of myozin is called H - strip, and a plot containing the filament of actin and myosin - and the strip. Disk I flashes zin. Z - Line (BELFRAGMA) is formed by an alpha-agctin protein having a media location. Proteins, nebulin and Totin contribute to the location of the acts of actin and myosin and their fixation in the Z-strip. The bodyfragm of adjacent beams is fixed with each other, as well as with the cortical layer of sarcoplasm with intermediate filaments. This contributes to the solid fixation of the discs and does not allow them to shift relative to each other.

Structural functional unit Miofibrill is sarcomer , within its limits there is a reduction in muscle fiber. It is represented by ½ I-disk + A-drive + ½ I-disk. When reducing the filament of actin, there are between the threads of myosin, inside the strips and disk i as such disappears.

Between beams, myofibrils is a chain of sarcos, as well as the tanks of the sarcoplasmic network at the level of the T-tube forming transversely located tanks (L-systems).

3. Specific membrane apparatus - It is formed by the T-tube (this is invagination of the cytlemma), which in mammals is at the level between dark and bright disks. Next to the T-tube there are terminal tanks of the sarcoplasmic network - agranular EPS, in which calcium ions accumulate. T-tube and two L-tanks form in aggregate triad . Triads play an important role in the initiation of muscle contraction.

4. Support - Educated meso - I. bulfragmami performing a reference function for a beam of myofibrils, as well as sarchatima . Sarchatimma (Muscular Fiber Sheath) is represented by two sheets: internal plasmolm, outdoor - basal membrane. Collagen and reticular fibers, forming the interlayer of connective tissue with vessels and nerves - in sarclatma endomisiumsurrounding every fiber. Cells are located miosatellite Or myosatellitocytes - this type of cells is also formed from the Miotomes, giving two populations (myoblasts and myosatelistic). These are oval cells that have an oval kernel and all organelles and even a cell center. They are unlikely and participate in muscle fiber regeneration.

5. Nervous apparatus (See Nervous System - Motor Plaside).

Regeneration of skeletal cross-striped muscular fabric can go through:

1. compensatory hypertrophy,

2. Either the following way: when cutting muscle fiber, it is degenerating next to the cut and absorbed by macrophages. Then, in differentiated tanks, the EPS and the Golgi complex begin to form elements of sarcoplasm, and thickening is formed at the damaged ends - muscle kidneys growing towards each other. The myostels released during damage to the fiber are divided, merge among themselves and contribute to regeneration by completing in muscle fiber.

Histoophysiology of muscle contraction.

Molecule aktin It has a globular shape and consists of two chains globule, which spirally twist relative to each other, while the grooves are formed between these threads, which contains tropomyosine protein. The troponin protein molecules are located between the tropomosin at a certain distance. In calm state, these proteins cover the active centers of the actin protein. As a reduction, an excitation wave arises, which from the sarchatomma is transmitted by the T-tubes in the museum of muscle fiber and the sarcoplasmic network L-tank, calcium ions are ejected, which change the troponin configuration. Following this, Troponin shifts tropomyosine, resulting in active actorn protein centers. Belka molecules mozin Have a kind of golf stick. It distinguishes two heads and handle, while the heads and part of the handle are movable. During the reduction of myozin's head, moving along the active centers of the actin protein, tighten the actin molecules inside the drive of the disk A and the disk i almost disappears.

Muscle as an organ.

Muscular fiber is surrounded by a thin layer of loose fibrous connective tissue, this layer is called endomisium There are vessels and nerves in it. A bundle of muscle fibers is surrounded by a wider layer of connective tissue - visitia , and the whole muscle is covered with a dense fibrous connective tissue - epimise .

Distinguish three types of muscle fibers :

2. Red,

3. Intermediate.

White - (skeletal muscles), this is a volitional, fast-cutting muscles, which, with a reduction, is quickly tired, is characterized by the presence of ATP - the phase of the rapid type, and the low activity of succinate dehydrogenase, high-phosphorylase. The kernels are located along the periphery, and the myofibrils in the center, Belfragma at the level of a dark and light disk. White muscle fibers contain more myofibrils, but less than myoglobin, large glycogen stock.

Red - (Heart, Language) is an unallic muscles, the reduction of these fibers is a protracted tonic, without fatigue. Slow-type ATP phase, high activity of succinate dehydrogenase, low-phosphorylase, kernels are located in the center, myofibrils along the periphery, Belfragma at the T-tube level, contains more Mioglobin, providing red color of fibers than myofibrils.

Intermediate (Part of skeletal muscles) - occupy an intermediate position between the red and white type of muscle fibers.

Heart muscular fabric.

Educated 5 types of cells:

1. typical (contractile) musculature,

2. atypical - comprises R-cells (Paismaker cells) in the cytoplasm of which a lot of free calcium. It has the ability to excite both the impulse generation, are part of the rhythm driver, providing heart automatism. The pulse with the R-cell is transmitted to

3. transitional cells and then on

4. conductive Cells, with typical myocardium.

5. secretoryWe produce a sodium system, while they control the urinations.

Cardiac muscular fabric Refers to transverse and has a similar structure, as well as skeletal (i.e., there are the same devices), but differs from skeletal as follows:

1. If the skeletal muscle tissue is a symplast, then the hearter - has a cellular structure (cardiomyocytes).

2. Cardiomyocytes are connected with each other and form functional fibers.

3. Insert plates - these are boundaries between cells having complicated structure and containing interdigate, nexus and desplaomomomomas where the actin's threads are woven.

4. Cells have one, two cores located in the center. And the bunches of the Miofibrill lie along the periphery.

5. Cardiomyocytes form cytoplasmic grows or oblique anastomoses, connecting functional fibers (therefore, the heart works according to the law "All or Nothing").

6. For cardiac muscular fabric, a red muscles type is characteristic (see above)

7. There is no source of regeneration (there are no myostels), regeneration is due to the formation of a connective tissue scar at the place of lesion or compensatory hypertrophy.

8. Develops from the mioepcardial plate of visceral sheet of the splash.