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WHERE AM I?

WHERE AM I?. Online Anatomy Module 1. INTRO & TERMS. CELL. EPITHELIUM. CONNECTIVE TISSUE. MUSCLE. NERVOUS SYSTEM. AXIAL SKELETON. APPENDICULAR SKELETON. MUSCLES. EMBRYOLOGY. MUSCLE. see Marieb pp. 82-84, 153-166. MUSCLE CELL’S ROLE.

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WHERE AM I?

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  1. WHERE AM I? Online Anatomy Module 1 INTRO & TERMS CELL EPITHELIUM CONNECTIVE TISSUE MUSCLE NERVOUS SYSTEM AXIAL SKELETON APPENDICULAR SKELETON MUSCLES EMBRYOLOGY

  2. MUSCLE see Marieb pp. 82-84, 153-166

  3. MUSCLE CELL’S ROLE Muscle cell contracts along an axis to furnish force applied to what it is attached to

  4. MUSCLE CELL = MUSCLE FIBER Muscle cells are often called muscle fibers. Note the distinction with connective tissue cells, which construct extracellular fibers such as collagen. Muscle cells are also called ‘myocytes’, e.g., cardiomyocyte

  5. MUSCLE ACTIONS Visceral Somatic lumen skeletal muscle rotation around joint* squeezing/ * constriction Muscle cells work together as ‘muscles’ (abs. etc) or layers of heart or tubes, for a purpose * how the force is applied

  6. MUSCLE CONTRACTION: Requirements Force Generated Applied usefully Controlled Energized Sustained Variedfor conditions

  7. MUSCLE CONTRACTION: Requirements GENERATED by interactions between actin & myosin Applied usefullyconnective tissues to tendons; visceral & cardiac muscle contract in a circle CONTROLLED voluntary & involuntary: nervous; & nervous + diffuse chemical control ENERGIZED blood supply; mitochondria ; ATP; glycogen - stored form of glucose SUSTAINED multiple muscle units; prolonged contraction (smooth muscle) VARIED FOR CONDITIONS sub-types of muscle The diverse requirements demand 3 three separate kinds of muscle

  8. MUSCLE CONTRACTION: Requirements GENERATED by interactions between actin & myosin

  9. ACTIN & MYOSIN FILAMENTS IN MUSCLE Z line/disc thickMYOSIN filament thinACTIN filament In muscle, for strong shortening (contractile) force the actin filaments are stabilized and interdigitated with thicker myosin filaments, which pull them in deeper

  10. SKELETAL MYOFIBER IN LONGITUDINAL EM VIEW I band A band I band H zone with M line Z line/disc thickMYOSIN filament thinACTIN filament Banding pattern - I & Abands, Z lines, H zones, M lines The regular arrangement of the filaments & their attachments yields a visible banding pattern across the fiber

  11. BANDING-PATTERN CHANGES IN CONTRACTION A band I band I band actin myosin M line but noH zone Z line 1 Sarcomere shortens 3 A band unchanged 2 I band shortens 4 H zonedisappears

  12. SKELETAL MYOFIBER: Generating contraction H zone with M line Z line/disc thickMYOSIN filament thinACTIN filament Tails of heavy (H) myosin bundle together to make the myosin filament ACTIN filament attached globular F actin molecules H & L myosin heads hinge step-wise along actin filament

  13. Actin-myosin interaction to generate myosin’s pull on actin filament Myosin head / Motor domain Parts of Motor domain Actin-binding site ATP-catalysing site Regulatory domain interacts with tropomyosin under control of Ca 2+--switched troponin Thick filament- Rods of H myosin Catalytic domain Actin filament myosin rods held stationary Regulatory domain does the lever work, aided by the flexible start of the rod 2 1 Actin filament pulled

  14. MUSCLE CONTRACTION: Requirements Applied usefullyconnective tissues to tendons;

  15. SKELETAL MUSCLE striated/cross-banded myofiber capillary sarcolemma TENDON endomysium CT Myofiber in cross-section myofibrils

  16. SKELETAL MUSCLE: Connective Tissue Organization MYOCYTE PERIMYSIUM } creates FASCICLE/ bundle endomysium EPIMYSIUM

  17. SKELETAL MUSCLE myofibrils striated/cross-banded myofiber capillary sarcolemma TENDON endomysium CT Myofiber in cross-section

  18. Myofiber in cross-section myofibrils Each myofibril consists of bundled myofilaments thickMYOSIN But, at regular intervals along the relaxed fiber, only thin or only thick filaments are found. Why? thinACTIN

  19. PERIPHERAL MYOFIBRIL IN LONGITUDINAL EM VIEW I band A band I band Z line/disc thickMYOSIN filament thinACTIN filament Hits thick & thin Hit only thin

  20. MUSCLE CONTRACTION: Requirements CONTROLLED voluntary & involuntary: nervous; & nervous + diffuse chemical control

  21. SKELETAL MUSCLE: INNERVATION Axons/nerve fibers to motor end-plates to cause contraction striated/cross-banded myofiber TENDON

  22. MOTOR END-PLATE or NEUROMUSCULAR/MYONEURAL JUNCTION AXON AXOLEMMA SARCOLEMMA SCHWANN CELL SYNAPTIC VESICLES mitochondrion synaptic cleft secondary/ junctional folds of POST-SYNAPTIC MEMBRANE SKELETAL MUSCLE FIBER/MYOCYTE

  23. MOTOR END-PLATE: LOCATION OF ‘TRANSMISSION’ MOLECULES voltage-gated ion channels SARCOLEMMA AXOLEMMA voltage-gated ion channels Acetyl Choline/ACh SYNAPTIC VESICLES synaptic cleft Cholinesterase Ligand-gated ion channels PRE-SYNAPTIC MEMBRANE ACh receptors POST-SYNAPTIC MEMBRANE SKELETAL MUSCLE FIBER/MYOCYTE Ca2+ channels

  24. SKELETAL MYOFIBER: Initiating contraction motor end-plate T/transverse tubule sarcolemma A-I junction Z line } Sarcoplasmic reticulum wraps around myofibril and releasesCalcium ion, when stimulated viaT-tubule&feet Triad = T-tubule + two terminal cisternae Feet Terminal cisterna of SR Motor end-plate - Sarcolemma AP - T-tubule AP - Feet - SR - Ca 2+ release

  25. MUSCLE CONTRACTION: Requirements CONTROLLED voluntary & involuntary: nervous; & nervous + diffuse chemical control ENERGIZED blood supply; mitochondria ; ATP; glycogen - stored form of glucose

  26. AROUND EACH MYOFIBRIL, meaning between myofibrils Glycogen granules Sarcoplasmic reticulum energize control Myofilamentsgenerate force Mitochondria energize MYOFIBRIL

  27. THREE MAIN TYPES OF MUSCLE SMOOTHsmall but prolongable force; diverse types, uses, & controls; controlled partly by autonomic/involuntary nervous system, partly by chemicals released from nearby cells, and by cell-to-cell connections CARDIACstrong rhythmic contractions; controlled by own cell-to-cell connections; pace determined by autonomic innervation to a little of the cardiac muscle SKELETALmost forceful kind, but contracts only in response to voluntary/somatic nervous system activity; applies its force via well-organized connective tissue; strength of contraction needs high internal organization within the muscle cell/fiber

  28. THREE MAIN TYPES OF MUSCLE I SMOOTH small but prolongable force; diverse types, uses, & controls; controlled partly by autonomic/ involuntary nervous system, partly by chemicals released from nearby cells, and by cell-to-cell connections

  29. THREE MAIN TYPES OF MUSCLE II CARDIAC strong rhythmic contractions; controlled by own cell-to-cell connections; pace determined by autonomic innervation to a little of the cardiac muscle

  30. THREE MAIN TYPES OF MUSCLE III SKELETALmost forceful kind; but contracts only in response to voluntary/somatic nervous system activity; applies its force via well-organized connective tissue; strength of contraction needs high internal organization within the muscle cell/fiber

  31. THREE MAIN TYPES OF MUSCLE IV Muscle cells are often called muscle fibers. Note the distinction with connective tissue cells, which construct extracellular fibers such as collagen. Muscle cells are also called ‘myocytes’, e.g., cardiomyocyte

  32. THREE MAIN TYPES OF MUSCLE: Sub-types SMOOTHskin, cardiovascular, airway, uterine, otherreproductive, urinary, gastrointestinal (GI) CARDIACatrial, ventricular, nodal, Purkinje SKELETALtype I - slow, type IIa - fast oxidative, type IIb - fast glycolytic

  33. SKELETAL MYOFIBER: Needs determining structure Generation Force generation Stabilization Force application Control of contraction Energize

  34. CARDIAC MUSCLE striated/cross-banded CARDIOMYOCYTES INTERCALATED DISK Reticular fiber centralNUCLEUS Capillary branching muscle fibers Sarcolemma & external lamina

  35. INTERCALATED DISC - electro-mechanical union ID is a strong myocyte-myocyte attachment + electrical connections Fascia adherensstrength Maculae adherensstrength Gap junctiontransmits contraction

  36. PURKINJE FIBER ventricle } Endocardium Sub-endocardium Large, pale cell specialized for conduction, not contraction Myofilaments Glycogen

  37. SMOOTH MUSCLE SMOOTH MUSCLE CELL has same contractile & control *machinery as skeletal myocyte, but less organized Reticular fiber Gap junction/Nexus Autonomic nerve axon Myocyte plasmalemma + glycoprotein External lamina * There is the important difference that smooth muscle uses Myosin Light-chain Kinase (MLCK) to phosphorylate the regulatory myson light chain as the main means to provoke the actomyosin ATPase to start contraction

  38. SMOOTH MUSCLE SMOOTH MUSCLE CELL has same contractile & control machinery* as skeletal myocyte, but less organized Filaments attach to DENSE BODIES serving the role of Z-lines CAVEOLAE for stimulus-contraction coupling serve role of T-tubule & SR system

  39. SMOOTH MUSCLE * There is the important difference that smooth muscle uses Myosin Light-chain Kinase (MLCK) to phosphorylate the regulatory myosin light chain as the main means to provoke the actomyosin ATPase to start contraction

  40. CAVEOLA Caveolae are plasma membrane invaginations found in most cell types of all four tissues. They are conspicuous in endothelial cells & smooth muscle. Membrane molecules: Caveolin - characteristic integral membrane protein Cholesterol (lots) Molecules related to - Plasmalemma Transcytosis Endocytosis or Signal transduction

  41. SMOOTH MUSCLE View with H & E staining - solid pink mass (stained sarcoplasm) cross-section long.-section Unseen are reticular and nerve fibers, plasmalemmas & external laminae Trichromestains distinguish smooth muscle cells from collagen fibers

  42. SKELETAL MYOFIBER: Needs determining structure Generation Force generation Stabilization Force application Control of contraction Energize

  43. MYOFIBER: Stabilization* & Force Application materials Dystrophin Integrin External lamina Sarcolemma M line* Nebulin* a-actinin* Desmin* intermediate filaments Z line Titin* (“elastic”)

  44. SKELETAL MUSCLE: SENSORY INNERVATION striated/cross-banded myofiber TENDON Golgi tendon receptor Muscle spindle Sensory axon & spindle receptor The fine control of contraction in individual myofibers requires abundant sensory feedback on how the muscle as a whole is performing

  45. CARDIAC MUSCLE striated/cross-banded CARDIOMYOCYTES INTERCALATED DISK Reticular fiber centralNUCLEUS Capillary branching muscle fibers Sarcolemma & external lamina

  46. CARDIAC PATHOLOGY Enlarged, but altered and weakened muscle of Ventricular hypertrophy More & thicker fibers of Fibrosis Reticular fiber Capillary Bad gap junctions Arrythmia altered connexin Blocked vessels damaged heart muscle (Cardiac infarct)

  47. Caution how you exit. BACK on your browser is needed Unfortunately there is no way that you can directly reach other topics listed here by clicking on them. You get there by going back to the Paramedical Anatomy menu WHERE AM I? Online Anatomy Module 1 You are at the End ORIENTATION CELL EPITHELIUM CONNECTIVE TISSUE MUSCLE NERVOUS SYSTEM AXIAL SKELETON APPENDICULAR SKELETON MUSCLES EMBRYOLOGY

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