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Muscle Contraction Pictures

Muscle Contraction Pictures. Muscle Terminology. Myo Mys Sarco Muscle fiber . Slide 2. 1. Action potential arrives at axon terminal of motor neuron. Ca 2+. Ca 2+. Synaptic vesicle containing ACh. Mitochondrion. Axon terminal of motor neuron.

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Muscle Contraction Pictures

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  1. Muscle Contraction Pictures

  2. Muscle Terminology • Myo • Mys • Sarco • Muscle fiber

  3. Slide 2 1 Action potential arrives at axon terminal of motor neuron. Ca2+ Ca2+ Synaptic vesicle containing ACh Mitochondrion Axon terminal of motor neuron Synaptic cleft Fusing synaptic vesicles ACh Junctional folds of sarcolemma Sarcoplasm of muscle fiber

  4. Slide 3 Axon terminal Open Na+ Channel Closed K+ Channel Na+ Synaptic cleft ACh K+ Na+ K+ + + + + ACh + + + + + + Action potential n + + o i t Na+ K+ a z 2 i r Generation and propagation of the action potential (AP) a l o p e d f o e v a W 1 1 Local depolarization: generation of the end plate potential on the sarcolemma Sarcoplasm of muscle fiber

  5. The Neuromuscular Junction

  6. Epimysium Bone Tendon Blood vessel Fascicle (wrapped by perimysium) Endomysium (between individual muscle fibers) Muscle fiber Fascicle Perimysium Figure 9.1a Connective tissue sheaths of skeletal muscle: epimysium, perimysium, and endomysium.

  7. Thin (actin) filament Z disc H zone Z disc Thick (myosin) filament I band A band Sarcomere I band M line (c) Small part of one myofibril enlarged to show the myofilaments responsible for the banding pattern. Each sarcomereextends from one Z disc to the next. Figure 9.2c Microscopic anatomy of a skeletal muscle fiber.

  8. Sarcomere Z disc Z disc M line Thin (actin) filament Elastic (titin) filaments Thick (myosin) filament (d) Enlargement of one sarcomere (sectioned lengthwise). Notice the myosin heads on the thick filaments. Figure 9.2d Microscopic anatomy of a skeletal muscle fiber.

  9. Thin Filaments • Actin - two strands of fibrous (F) actin protein intertwined • Globular (G) actin - has active site for myosin • Tropomyosin molecules – regulatory protien that block active sites of G actin when muscle is relaxed • Troponin - small calcium-binding protein molecules stuck to tropomyosin

  10. Striations

  11. Spinal cord Axon terminals at neuromuscular junctions Branching axon to motor unit Motor unit 1 Motor unit 2 Nerve Motor neuron cell body Motor neuron axon Muscle Muscle fibers (b) Branching axon terminals form neuromuscular junctions, one per muscle fiber (photo- micrograph 330x). (a) Motor Unit Figure 9.13 A motor unit consists of a motor neuron and all the muscle fibers it innervates.

  12. (a) Direct phosphorylation (b) Anaerobic pathway (c) Aerobic pathway Coupled reaction of creatine Glycolysis and lactic acid formation Aerobic cellular respiration phosphate (CP) and ADP Energy source: CP Energy source: glucose Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism Glucose (from glycogen breakdown or delivered from blood) Glucose (from glycogen breakdown or delivered from blood) CP ADP Creatine kinase O2 Glycolysis in cytosol Pyruvic acid Fatty acids Creatine ATP O 2 O2 Aerobic respiration in mitochondria Aerobic respiration ATP 2 Amino acids in mitochondria Pyruvic acid net gain O2 32 ATP CO2 Released to blood Lactic acid H2O net gain per glucose Oxygen use: None Oxygen use: None Oxygen use: Required Products: 1 ATP per CP, creatine Products: 2 ATP per glucose, lactic acid Products: 32 ATP per glucose, CO2, H2O Duration of energy provision: 15 seconds Duration of energy provision: 60 seconds, or slightly more Duration of energy provision: Hours Figure 9.19 Pathways for regenerating ATP during muscle activity.

  13. Single-Unit Smooth Muscle Multi-unit smooth muscle

  14. Sarcolemma Mitochondrion Myofibril Dark A band Light I band Nucleus (b) Diagram of part of a muscle fiber showing the myofibrils. Onemyofibril is extended afrom the cut end of the fiber.

  15. Slide 3 Action potential propagated down the T tubules. Steps in E-C Coupling: Sarcolemma Voltage-sensitive tubule protein T tubule Ca2+ release channel Terminal cisterna of SR Ca2+

  16. Slide 7 Actin Troponin Tropomyosin blocking active sites Ca2+ Myosin 3 Calcium binds to troponin and removes the blocking action of tropomyosin. Active sites exposed and ready for myosin binding Contraction begins 4 Myosin cross bridge The aftermath

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