MUSCLES

1. MUSCLES

2. 40-45 % of body mass • only system converting chemical energy into mechanical 2 types -skeletal (striated) -smooth

3. Structural unit - muscle fiber (myocyte) Contains many nuclei located along the cell

4. Muscle structure

5. Muscle structure

6. Chemical composition of skeletal muscles

7. Proteins of muscles 3 types: • proteins of sarcoplasma • proteins of miofibrils • proteins of stroma

8. Proteins of Sarcoplasma • Miogen fraction (enzymes of glycolysis etc.) • Albumins • Globulins • Myoglobin (chromoprotein, provides the red color to muscles, responsible for oxygen storage)

9. Proteins of Stroma • collagen • keratin • elastin are constituents of connective tissue of vessel walls, nerves, sarcolema.

10. Proteins of Miofibrils • Myosin (56-60 %) • Actin (20-25 %) • Tropomyosin (10-15 %) • Troponin complex (4-6 %)

11. Structure of filaments and myofibrils Sarcoplasma of striated muscle fibers contains myofibrils oriented along which are built of 2 types protein filaments: thick and thin

12. Muscle contraction is carried out due to the sliding of thick and thin filaments • Chemical energy – ATP hydrolysis • Contraction is regulated by Ca2+ concentration

13. Structure of Thick Filament • Thick filaments consist of myosin molecules • Myosin molecule built of 2 heavy (200000 Da) and 4 light (16000-25000 Da) chains • Heavy chains are coiled around each other and form the “tail” of the molecule • 2 light chains form the globular head of the molecule • The head has ATP-ase properties

14. About 400 molecules of myosin are combined in the thick filament

15. About half of molecules is directed to one end of filament, another half – to another end

16. Structure of Thin Filament Three proteins: actin, tropomyosin, troponin Two forms of actin: globular G-actin and fibril F-actin Molecules of globular actin are joined to form F-actin Two chains of F-actin are coiled in spiral In the groove of spiral of F-actin tropomiosin is located One molecule of tropomiosine contacts with 7 pairs of G-actin 1 molecule of troponin drops on 1 molecule of tropomiosin There are three subunits of troponin

17. Miofibrils contain about 2500 filaments There are 6 thin filaments for 1 thick filament

18. Structural unit of miofibril sarcomer • Both ends of thick miosin filaments are free • One end of thin filaments is attached to Z-plate

19. BIOMECHANISM OF MUSCLE CONTRACTION • Potential spreads along miofiber • Signal is transferred to cisterna of endoplasmic reticulum • Permeability of membranes for Ca2+ ions is changed and they get out into sarcoplasma • During the rest concentration of Ca2+in sarcoplasma is less than 10-7 mol/L • After Ca2+ exit from cisternas the concentration reaches 10-5 mol/L

20. Ca2+ binds to Ca-binding subunit of troponin • Conformation of protein is changed • Molecule of tropomiosin moves along groove of thin filament • As result centers for connection with heads of myosin are opened on the molecules of G-actin

21. Myosin heads combined with ATP bind to the closest molecules of G-actin • ATPase center is activated and ATP is hydrolized • Head bent • Sliding of thin filament along myosin • New ATP molecule binds to head of myosin • Bridge is torn • In the condition of Ca presence the head binds to the next actin molecule • Frequency - 50 times/s • Heads works not synchronously • Nervous impulses stop to come • Ca-ATPase transfers Ca2+ from sarcoplasma into cisternas • Complex Ca2+-troponin is dissotiated • Tropomiosin moves • Molecules of actin are blocked • Bridges are torn • Muscle relaxation

22. ATP is required both for contraction and relaxation of muscles • In ATP deficiency the bridges between actin and myosin are not torn • Filaments are fixed in connected state – muscle contraction (cadaver rigidity)

23. SOURSES OF ENERGY FOR MUSCLE WORK • ATP (5 umol for 1 g of tissue) – enough for 2-3 s • Kreatinphosphate – till 10 s • Glycolysis • Oxidative phosphorylation Êðåàòèíôîñôàò

24. RED AND WHITE MUSCLES Res fibers • Lot of myoglobin and mitochondria • Oxidative phosphorylation is active • Are contracted slowly, for a long time, no tiredness for long time White fibers • Little hemoglobin and mitochondria • More glycogen • Glycolisis is specific • Are contracted fast, fast tiredness

25. CONNECTIVE TISSUE

26. Present in all organs (50 % of body weight) • skin, • adipose tissue, • bones, • teeth, • fascia, • cartilages, • stroma of parenchymal inner organs, • walls of vessels.

27. THE STRUCTURE OF CONNECTIVE TISSUE Cells Fibers Extracellular matrix

28. Cells • Fibroblasts • chondroblasts Fibers • collagen • elastin Extracellular matrix carbohydrate-protein complexes - proteoglycans. Carbohydrate complexes of proteoglycans – heteropolysaccharides glycosaminoglycans (mucopolysaccharides). • fibroblasts chondroblasts

29. PROTEINS OF CONNECTIVE TISSUE Collagen • the most common protein in organism • 25-33 % of all protein (6 % of body weight) • Length - 300 nm, • Thickness –1,5 íì, molecular weight - 300 000

30. Consists of three polypeptide chains having the left spiral shape Three left coiled chains are again coiled together to form the right spiral bunch

31. 1 chain contains about 1000 amino acids 33 % - glycine 21 % – proline and oxiproline 11 %–alanine 35 % – all other amino acids Oxiproline andoxilysine are specific only for connective tissue

32. Collagen – complex protein, glycoprotein Carbohydrates (monosaccharide galactose and disaccharide galactosylglucose) bind by glycosidic bonds to the residues of oxilysine of polipeptide chain

33. Ланцюги стабілізуються водневими зв’язками м³æÑÎ- ³ NÍ-ãðóïами ïåïòèäíèõ çâ'ÿçê³â, ÎÍ-ãðóïами îêñèïðîë³íó. Ìîëåêóëè êîëàãåíóðîçòàøîâóþòüñÿ ðåãóëÿðíèì чèíîì ³ óòâîðþþòü ô³áðèëè, ç ÿêèõ ïîñë³äîâíî ôîðìóþòüñÿïóчêè ô³áðèë, âîëîêíà ³ ïóчêè âîëîêîí.

34. There are 12 types of collagens (differ from each other by the primary structure, types of chains, contents of carbohydrates,localization in organs and tissues). 4 main types:

35. Cross covalent links in the molecule of collagen

36. Reaction of aldoll condensation

37. Elastin The main constituent of elastic fibers in ligaments, walls of large arteries, lungs. Molecule contains about 800 amino acid residues Has globular shape. Is joined into the fibrous cords.

38. Contains a lot of glycine, alanine, proline, valine There are no oxilysine and cysteine Residues of lisine form the cross covalent bonds The net structure is formed which can strech two and more times.

39. PROTEOGLYCANS Proteoglycans – the main extracellular matrix of connective tissue. Consist of protein part + polisaccharide chains Molecular weight – tens millions. Polisaccharides - glycosaminoglycans (acidic mucopolisaccharides) are built from the large amount of identical disaccharide units. Disaccharide – aminosugar N-acetylglucosamin or N-acetylgalactosamin +uronic acid (glucuronic or iduronic)+sulfate(sometime).

40. Hyaluronic acid • Is contained in synovial fluid (lubricant in joints), vitreous substance of eye • In rheumatic diseases and arthritis hyaluronic acid is depolimerized and the viscosity of synovial fluid is decreased • Forms the viscous solutions • Retains water

41. Heparin • Is synthesized by tissue basofils • During degranulation is ejected into the extracellular matrix • Participates in the regulation of blood coagulation. • Increases the release of enzyme lipoprotein lipase into blood plasma