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Muscular System

Muscular System. What is the purpose of muscle?. Movement Posture Stabilize joints Generate heat. Types of Muscle. Compare all three muscle types. Look at: Location/number of nuclei Associated structures What controls the muscle contraction?

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Muscular System

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  1. Muscular System

  2. What is the purpose of muscle? Movement Posture Stabilize joints Generate heat

  3. Types of Muscle • Compare all three muscle types. • Look at: • Location/number of nuclei • Associated structures • What controls the muscle contraction? • You should be able to answer the “Practice” questions on page 301when finished.

  4. Skeletal Muscle

  5. Smooth Muscle

  6. Cardiac Muscle

  7. Skeletal Muscle

  8. Structure of Skeletal Muscle Muscle (wrapped in fascia, epimysium) Fascicles (bundles of muscle fibers, wrapped in perimysium)  Muscle Fibers (cells, wrapped in endomysium)  Myofibrils  Filaments

  9. Structure of Skeletal Muscle

  10. Skeletal Muscle Fibers • Skeletal muscle fiber = single muscle cell • Multinucleated • Striated • Myofibrils: myosin (thick filaments) and actin (thin filaments) • Myosin and actin alternate forming striations (light and dark areas)

  11. Skeletal Muscle Fibers • Sarcomeres – pattern of actin/myosin alternating throughout muscle fiber • Contractile unit of muscle • Sarcolemma– cell membrane of muscle cells • Sarcoplasm – cytoplasm of muscle cells

  12. Muscle Video http://www.youtube.com/watch?v=EdHzKYDxrKc

  13. Gross Muscle Anatomy • Muscle • Epimysium • Endomysium • Perimysium • Fascicle • Muscle fiber/cell • Myofibrils • Sarcolemma • Sarcoplasm

  14. Skeletal Muscle Layout • Actin • Myosin • Z line • I band • A band • H zone • Sarcomere • Sarcoplasmic Reticulum

  15. Muscle Filaments (Myofibrils) • Myosin: composed of many myosin fibers • Heads and tails • Forms cross-bridge with actin • Heads of myosin come in contact with actin during muscle contraction • Actin: double strands twisted into a helix • Troponin – wraps around actin • Tropomyosin – contact point for myosin

  16. Muscle Filaments: Actin • Troponin • Tropomyosin • Thin filament

  17. Muscle Filaments: Myosin • Heads • Tails • Thick filament

  18. Sarcoplasmic Reticulum • Corresponds with the endoplasmic reticulum in other cells • Cisternae • Enlarged portions of SR on either side of the T tubule • Transverse tubules (T tubules) • Extends into sarcoplasm, contains extracellular fluid

  19. Sarcoplasmic Reticulum • T tubule • Sarcoplasmic reticulum • Sarcomere • Myosin • Actin • Sarcolemma • Mitochondria • Myofibril

  20. Skeletal Muscle Contraction

  21. Muscle Contraction Occurs when thin and thick filaments slide past one another Shortens sarcomeres/whole muscle cell Stimulated by neurons

  22. Neuromuscular Junction • Motor neurons control skeletal muscle • Neuromuscular junction: where nerve cell synapses with the muscle • Motor end plate: specialized part of muscle to receive neural signals (higher amount of mitochondria, nuclei/SR)

  23. Neuromuscular Junction • One motor neuron can innervate many muscle cells • Motor unit: neuron AND the muscle(s) it controls

  24. Synaptic Cleft Separation between the neuron and the muscle Nerve fiber releases synaptic vesicles containing neurotransmitters into the synaptic cleft

  25. Neurotransmitter for Skeletal Muscle Contraction • Acetylcholine (ACh) • Increases membrane permeability to sodium • Sodium influx causes muscle impulse which transmits the contraction along the muscle • Through the sarcoplasmic reticulum, cisternae, T tubules

  26. Sliding Filament Theory • Sarcomeres shorten through movement of actin and myosin sliding past one another, not shortening themselves • H zone, A bands narrow • Z lines come closer together • Needs ATP (energy), Ca2+

  27. Sliding Filament Theory http://www.youtube.com/watch?v=Vlchs4omFDM

  28. Sliding Filament Theory • Summarize the contraction cycle in your textbooks (pg. 292) • Summarize relaxation • What enzyme is needed? What does this enzyme do? • When ACh breaks down, what happens?

  29. Myoglobin • Cellular respiration is critical in muscle contraction • Myoglobin stores oxygen in muscle cells • Gives muscle the reddish/brown color • Similar to what other molecule?

  30. Anaerobic Threshold • Lactic acid threshold • Muscle forms lactic acid in absence of oxygen • Anaerobic respiration

  31. Muscle Fatigue • Loss of ability to contract • Caused by: decrease in blood flow, ion imbalances, accumulation of lactic acid in muscle tissue • Cramps: sustained contraction of muscle • Changes in extracellular matrix of muscle causes extended contraction

  32. Heat Production Muscle is a major source of body heat Blood transfers heat throughout body

  33. Fast Twitch vs. Slow Twitch Muscles Use your textbook to compare and contrast fast twitch and slow twitch muscles Give some examples for the ideal muscle types for different activities Use human and animals in your answer.

  34. Major Skeletal Muscles

  35. Remembering Muscle Names http://www.youtube.com/watch?v=bUnzlkZGkvM

  36. Muscles of the Head http://www.gwc.maricopa.edu/class/bio201/head/head1b.htm Muscles of facial expression Muscles of mastication

  37. Muscles of Facial Expression • Epicranius • Frontalis • Temporalis • Orbicularis occuli • Orbicularis oris • Buccinator

  38. Muscles of Facial Expression

  39. Muscles of Mastication Masseter – elevates mandible Temporalis – elevates mandible

  40. Muscles of the Neck Sternocleidomastoid – pulls head to one side, flexes neck, elevates sternum

  41. Muscles of Mastication

  42. Muscles of the Pectoral Girdle Trapezius – rotates scapula, pull scapula (raise, medial, downward) Rhomboid major – connects scapula with vertebrae Rhomboid minor – smaller than rhomboid major, connects scapula with vertebrae Levator scapulae – elevates scapula

  43. Muscles of Pectoral Girdle

  44. Muscles of the Pectoral Girdle • Levator scapulae • Trapezius • Rhomboid major and minor • (external oblique) • (Latissimusdorsi) • (Deltoid)

  45. Before we can discuss the movement of the arm…

  46. Before we can discuss the movement of the arm… • We need to get into the muscle actions: • Flexor – flexion – bend at joint so angle between two parts gets closer together • Extensor – extension – straightening joint so angle between two parts increases • Abductors – abduction – movement away from the midline • Adductors – adduction – movement toward the midline • Rotators – movement around an axis

  47. Muscles that move the Upper Arm Posterior: http://www.gwc.maricopa.edu/class/bio201/muscle/musc14.htm Anterior: http://www.gwc.maricopa.edu/class/bio201/muscle/musc13.htm

  48. Shoulder Muscles Posterior Shoulder: http://www.gwc.maricopa.edu/class/bio201/muscle/arm/shldrp.htm Anterior Shoulder: http://www.gwc.maricopa.edu/class/bio201/muscle/arm/shldra.htm

  49. Flexors that move the upper arm • Coracobrachialis • Scapula to middle of humerus • Flexes and adducts arm • Pectoralis major • Thick muscle of upper chest • Flexes, adducts, rotates arm medially

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