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Muscle Tissue

Muscle Tissue. Organization of Skeletal Muscle ( macro scopic anatomy). What do the following prefixes mean: peri - , endo - , epi - , myo - , and sarco - ? Describe how a muscle attaches to a bone, as shown in this figure.

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Muscle Tissue

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  1. Muscle Tissue

  2. Organization of Skeletal Muscle(macroscopic anatomy) What do the following prefixes mean:peri-, endo-, epi-, myo-, andsarco-? Describe how a muscle attaches to a bone, as shown in this figure. Why is there such a large connective tissue component to skeletal muscles?

  3. Internal organization of a muscle cell: What are cisternae and what chemical is stored within the cisternae of muscle cells? What is a myofibril? = actin = myosin What is the functional unit of contraction in a muscle fiber? Circle and/or label one in this diagram. Each t-tubule is an extension of the ________________.

  4. A Sarcomere within a Myofibril Organization of Myofilaments in a Sarcomere

  5. Energy Metabolism in Muscle Cells(pages 165 & 166 in the course packet) The phosphagen system Aerobic cellular respiration Fermentation (anaerobic metabolism) What molecule serves as the energy source for fermentation? Where does the muscle cell get these molecules?

  6. The ATP cycle Energy from food molecules • ATPase breaks the last phosphate bond, releasing energy • leaves ADP (adenosine diphosphate) and Pi • ATP synthase catalyzes the addition of the terminal phosphate group back onto ADP • Name the two locations where ATP synthesis takes place in a cell.

  7. Phosphagen System(Creatine Phosphate) Can cells store ATP? Can cells store CrP? Name the enzyme that controls these reactions. Where would you find this enzyme, and why?

  8. Anaerobic ATP Synthesis(Fermentation) Which source of fuel molecules is more important, and why? Why is anaerobic muscle work more powerful than aerobic muscle work? What are the consequences of lactic acid production? What is the relationship between lactic acid in the blood and “oxygen debt”?

  9. Aerobic Cellular Respiration What’s wrong with this figure?! Write the summary equation for aerobic cellular respiration. What are the benefits of aerobic cell metabolism? What substrate(s) are available for aerobic energy metabolism? … for anaerobic metabolism?

  10. Motor Units:The functional unit of movement Describe at least two ways that these neurons controlled. How many muscle cells are in motor unit 1? How many neurons in motor unit 1? What is the functional classification of the neuron in motor unit 1?

  11. The Neuromuscular(Myoneural) Junction The appropriate term to describe an axon branch (as shown in these figures) is ___________________. The appropriate stimulus for skeletal muscle cells is _____________________. The specialization of the sarcolemma that contains receptors for acetylcholine(ACH) is called ___________________.

  12. The Transmembrane Electrochemical Potential K+ is often allowed to “leak” out of the cell. How does the Na-K pump contribute to the “potential”? Why is the cell membrane described as “polarized”?

  13. The Action Potential • At time 0, does the membrane begin to depolarize or repolarize? • Unlike the graded potentials that get larger with increasing stimulus strength (e.g. at the motor end plate), the action potential is an all-or-none* response. • Will a stronger stimulus produce a larger action potential? Explain. • Give an example of where a gradedpotential would take place.

  14. Refractory Period Differentiate between the absolute refractory periodand the relative refractory period. Why is the refractory period important in muscle cells? Why is the refractory period important in neurons? Refractory Period from L. = “stubborn”

  15. Chemical Synapses The calcium channels on the synaptic terminal are -gated. The sodium channels on the post- synaptic membrane are -gated. The ion channels involved in the propagation of the Action Potential are -gated.

  16. Vesicle Transport in Exocytosis

  17. Events at the Neuromuscular Junction Is the release of neurotransmitter active transport or passive transport? Is the influx of Na+ ions by active transport or passive transport? How does the influx of Na+ ions change the transmembrane electrochemical potential?

  18. Are the calcium channels in cisternae voltage-gated or chemically-gated? • Besides Ca+2, what must also be present in order for myosin to bind to actin? • Study the outline beginning on page 170 in your packet.

  19. Muscle fiber Motor neuron Nucleus

  20. Sarcoplasmic reticulum (SR) Sarcolemma Myofibrils SR Cistern T-tubule (a portion of the sarcolemma is peeled away in this view)

  21. Action potential reaches synaptic terminal of motor neuron

  22. New AP generated at motor end-plate and propogated down T-tubules

  23. Myofibrils (relaxed) Sarcomere (Sarcolemma and other structures not shown)

  24. Myofibrils (contracted) Sarcomere

  25. Sarcomere (relaxed) Myosin (thick filaments) Actin (thin filaments)

  26. Sarcomere (contracted) Myosin (thick filaments) Actin (thin filaments)

  27. Myosin heads Actin (thin filament) Myosin (thick filaments)

  28. Protein complex Actin Myosin head ADP and phosphate Note that ATP is hydrolyzed at this point, but still attached to myosin head.

  29. Calcium ion Protein complex Myosin-binding sites (exposed) ADP and phosphate

  30. Actin Myosin head ADP and phosphate

  31. Actin Myosin head ADP Pi • Release of Pi initiates the power stroke. • At the end of the power stroke, ADP is released. • A new ATP is required for myosin to release its hold on actin.

  32. Actin Myosin head ATP ATP binds to the myosin head, causing it to detach from actin.

  33. Actin Myosin head ADP and phosphate When the ATP is broken down to ADP and phosphate, the myosin head extends.

  34. Actin Myosin heads The sequence repeats as long as calcium ions are present. The combined work of many myosin heads causes the actin filaments to slide past the myosin filaments.

  35. Protein complex Actin Myosin heads When the action potentials stop, calcium ions are pumped back into the ER, the myosin-binding sites on actin are again blocked, and the muscle relaxes.

  36. Calcium Myosin (Ca+2 in green) Actin Sarcomere

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