Musculoskeletal Lecture


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Musculoskeletal Lecture

  1. 1. Locomotion – Skeletal and Muscular Systems <ul><li>Movement is based on Muscles acting on a rigid skeleton </li></ul><ul><li>All animals employ the use of muscles </li></ul>
  2. 2. Types of Skeletons <ul><ul><li>Hydrostatic </li></ul></ul><ul><ul><li>Fluid filled cavity encircled by muscle fibers </li></ul></ul><ul><ul><li>Soft-bodied invertebrates </li></ul></ul><ul><ul><li>Exoskeleton </li></ul></ul><ul><ul><li>Body encased in hard shell chitin </li></ul></ul><ul><ul><li>most be shed for growth </li></ul></ul><ul><ul><li>limits body size as exoskeleton has to grow increasingly thicker and heavier </li></ul></ul><ul><ul><li>Endoskeleton </li></ul></ul><ul><ul><li>rigid internal skeleton of bone </li></ul></ul>
  3. 3. Types of Skeletons <ul><li>Endoskeletons - rigid internal skeleton to which muscles are attached </li></ul><ul><ul><li>composed of cartilage or bone </li></ul></ul><ul><ul><li>vertebrate skeleton </li></ul></ul><ul><ul><ul><li>axial skeleton - forms axis of body and supports organs of the head, neck, and chest </li></ul></ul></ul><ul><ul><ul><li>appendicular skeleton - includes bones of the limbs, pectoral and pelvic girdles </li></ul></ul></ul>
  4. 4. Exoskeleton and Endoskeleton
  5. 5. Skeleton <ul><li>Functions </li></ul><ul><li>Homeostatic </li></ul><ul><ul><li>Ca + and P + reservoir </li></ul></ul><ul><li>Biomechanical </li></ul><ul><ul><li>Attachment for muscles </li></ul></ul><ul><ul><li>Protective covering brain and spinal cord </li></ul></ul><ul><li>Overview </li></ul><ul><li>Connective Tissue </li></ul><ul><ul><li>Extracellular matrix with collagen fibers (flexible) impregnated with crystals of Calcium phosphate (rigidity) </li></ul></ul><ul><li>Dynamic – reconstruction </li></ul>
  6. 6. Bone Tissue Structure <ul><li>Consists of Haversian System </li></ul><ul><ul><li>Run length of bone </li></ul></ul><ul><ul><li>Nerves/blood </li></ul></ul><ul><li>Osteoblasts - matrix </li></ul><ul><li>Osteocytes – encased </li></ul><ul><li>Osteoclast - breakdown </li></ul><ul><li>Concentric lamellae </li></ul><ul><ul><li>Around canal </li></ul></ul><ul><li>Lacunae - </li></ul><ul><li>Canaliculi </li></ul>
  7. 7. Classification of Joints (articulations) <ul><li>Joints – places where 2 bones are attached </li></ul><ul><li>TYPES </li></ul><ul><li>Immovable joints – dense connective tissue - little movement - sutures </li></ul><ul><li>Slightly movable joints – held together by cartilage </li></ul><ul><li>Some flexibility not much (intervertebral and symphyses) </li></ul><ul><li>Freely movable </li></ul><ul><li>Synovial Joints </li></ul><ul><li>Capsule with </li></ul><ul><li>fluid </li></ul><ul><li>Cartilage end caps </li></ul>
  8. 8. Types of Joints
  9. 9. Types of Joints
  10. 10. Types of Joints
  11. 11. Levers for movement <ul><li>Muscles attach to bone to allow movement – contraction = movement </li></ul><ul><li>Origin – nonmoving </li></ul><ul><li>Insertion – moving </li></ul><ul><li>Attach via tendons </li></ul><ul><li>Muscles oppose each other – Antagonistic </li></ul><ul><li>Muscles that cause the same action synergists </li></ul><ul><li>Isotonic contraction - muscle and all fibers shorten in length thus force of contraction remains relatively constant </li></ul><ul><li>Isometric contraction - tension is absorbed by tendons and other elastic tissue, and muscle does not change in length </li></ul>
  12. 12. Flexor and Extensor Muscles
  13. 13. Muscle Structure <ul><li>Muscle </li></ul><ul><li>Muscle fascicle </li></ul><ul><li>Muscle fibers = cell </li></ul><ul><li>Myofibrils </li></ul><ul><li>Thick and thin myofilaments </li></ul><ul><li>Myosin and Actin </li></ul>
  14. 14. Muscle Structure (Cont’d) <ul><li>Striated due to dark </li></ul><ul><li>and light bands </li></ul><ul><li>Pattern = organization of myofilaments </li></ul><ul><li>Repeating structure </li></ul><ul><li>“ Sarcomere” </li></ul><ul><li>Dark bands = “A” myosin </li></ul><ul><li>Light bands = “I” actin </li></ul><ul><li>Z line = actin attachment </li></ul><ul><li>H zone = myosin only </li></ul>
  15. 15. Sliding Filament Mechanism Mechanism of muscle contraction No shortening - sliding
  16. 17. The Players
  17. 18. muscle relaxed – myosin heads cocked – unable to Bind to actin due to sites blocked by protein - tropomyosin In order to contract tropomyosin must be moved to expose binding sites on actin Requires a regulatory protein troponin – troponin binds to tropomyosin changes the structure and exposes binding sites Troponin regulated by Calcium stored in the muscle cells If low calcium no binding sites exposed , if high calcium - exposed Preparing for Sliding
  18. 21. ATP is required <ul><li>Rigor mortis – body not make ATP (DEAD) cross-bridges cannot be broken </li></ul>
  19. 22. What causes sliding? <ul><li>Nervous system </li></ul><ul><li>involvement </li></ul><ul><li>When stimulated, </li></ul><ul><li>electrical impulse </li></ul><ul><li>travels down </li></ul><ul><li>T-tubules </li></ul><ul><li>Causes sarcoplasmic reticulum to release </li></ul><ul><li> Ca++ </li></ul>
  20. 23. Control of Muscle Contraction <ul><li>Nerves stimulate contraction </li></ul><ul><ul><li>Somatic motor neurons stimulate skeletal muscles. </li></ul></ul><ul><ul><ul><li>Axon extends from neuron cell body and branches to make synapses with a number of muscle fibers. </li></ul></ul></ul>
  21. 24. Control of Muscle Contraction <ul><li>Somatic motor neuron stimulates contraction: </li></ul><ul><ul><li>releasing acetylcholine neurotransmitter (ACh). </li></ul></ul><ul><ul><li>impulses spread along membrane and carried into the muscle fibers through the T tubules </li></ul></ul><ul><ul><li>T tubules conduct impulse toward the sarcoplasmic reticulum, which releases Ca ++ </li></ul></ul><ul><li>Excitation-contraction coupling </li></ul>
  22. 25. Control of Muscle Contraction <ul><li>Motor units and recruitment </li></ul><ul><ul><li>set of muscle fibers innervated by all axonal branches is defined as a motor unit </li></ul></ul><ul><ul><ul><li>division of muscle into motor units allows muscle’s strength of contraction to be finely graded </li></ul></ul></ul><ul><ul><ul><ul><li>most muscles contain motor units in a variety of sizes </li></ul></ul></ul></ul><ul><ul><ul><li>recruitment - nervous system’s use of increased numbers and sizes of motor units to produce a stronger contraction </li></ul></ul></ul>
  23. 26. Number and Size of Motor Units
  24. 27. Types of Muscle Fibers <ul><li>Muscle fiber twitches </li></ul><ul><ul><li>muscle stimulated with a single electric shock </li></ul></ul><ul><ul><ul><li>A second electrical shock delivered immediately after the first will produce a second twitch that may partially piggyback on the first ( summation ). </li></ul></ul></ul><ul><ul><ul><ul><li>At a particular frequency of stimulation, there is no visible relaxation between successive twitches ( tetanus ). </li></ul></ul></ul></ul>
  25. 28. Summation
  26. 29. Types of Muscle Fibers <ul><li>Skeletal muscle fibers can be divided on the basis of their contraction speed: </li></ul><ul><ul><li>Type I – slow-twitch fibers </li></ul></ul><ul><ul><ul><li>rich capillary supply, numerous mitochondria, and high concentration of myoglobin pigment (red fibers) </li></ul></ul></ul><ul><ul><li>Type II – fast-twitch fibers </li></ul></ul><ul><ul><ul><li>fewer capillaries and mitochondria and not as much myoglobin (white fibers) </li></ul></ul></ul>
  27. 30. Types of Muscle Fibers <ul><li>Muscle metabolism during rest and exercise </li></ul><ul><ul><li>Skeletal muscles at rest obtain energy from aerobic respiration of fatty acids. </li></ul></ul><ul><ul><ul><li>Skeletal muscles respire anaerobically for the first 45-90 seconds of moderate to heavy exercise. </li></ul></ul></ul><ul><ul><ul><li>Maximum rate of oxygen consumption in the body is called maximal uptake or aerobic capacity. </li></ul></ul></ul>
  28. 31. Types of Muscle Fibers <ul><li>Muscle fatigue and physical training </li></ul><ul><ul><li>Muscle fatigue refers to the use-dependent decrease in the ability of a muscle to generate force. </li></ul></ul><ul><ul><ul><li>usually correlated with the production of lactic acid by the exercising muscles </li></ul></ul></ul><ul><ul><ul><ul><li>also related to depletion of muscle glycogen </li></ul></ul></ul></ul>
  29. 32. Types of Muscle Fibers <ul><li>Endurance-trained athletes have a high aerobic capacity, and thus can perform more exercise before lactic acid production and glycogen depletion cause muscle fatigue. </li></ul><ul><ul><li>Weight training (resistance training) causes muscle fibers to become thicker as a result of increased size and number of myofibrils. </li></ul></ul><ul><ul><ul><li>cause skeletal muscles to grow by hypertrophy </li></ul></ul></ul>
  30. 33. Modes of Animal Locomotion <ul><li>In large animals, active locomotion is almost always produced by appendages that oscillate (appendicular locomotion) or by bodies that undulate, pulse, or undergo peristaltic waves (axial locomotion). </li></ul>
  31. 34. Modes of Animal Locomotion <ul><li>Locomotion in water </li></ul><ul><ul><li>Buoyancy reduces the influence of gravity. </li></ul></ul><ul><ul><ul><li>The primary force retarding forward movement is frictional drag. </li></ul></ul></ul><ul><ul><ul><ul><li>Swimming uses the body or its appendages to push against the water. </li></ul></ul></ul></ul>
  32. 35. Locomotion in Water
  33. 36. Modes of Animal Locomotion <ul><li>Locomotion on land </li></ul><ul><ul><li>Mollusks slide along a path of mucus. </li></ul></ul><ul><ul><li>Vertebrates and arthropods have a raised body and move forward by pushing the ground with a series of jointed appendages. </li></ul></ul><ul><ul><ul><li>Vertebrates have four limbs, while arthropods have six or more. </li></ul></ul></ul><ul><ul><ul><ul><li>basic walking pattern of all tetrapod vertebrates LH – LF – RH – RF </li></ul></ul></ul></ul>
  34. 37. Locomotion on Land <ul><li>Both arthropods and vertebrates achieve faster gaits by overlapping leg movements. </li></ul><ul><li>The highest running speeds of tetrapod vertebrates are obtained with asymmetrical gaits. </li></ul><ul><ul><li>galloping horse never supported by more than two legs, occasionally by none </li></ul></ul><ul><ul><ul><li>reduces friction against ground </li></ul></ul></ul><ul><li>Many vertebrates use peristaltic locomotion. </li></ul><ul><li>Most snakes employ serpentine locomotion. </li></ul>
  35. 38. Modes of Animal Locomotion <ul><li>Locomotion in air </li></ul><ul><ul><li>Flight has evolved four times: </li></ul></ul><ul><ul><ul><li>insects, pterosaurs, birds,and bats </li></ul></ul></ul><ul><ul><ul><li>propulsion achieved by pushing down against the air with wings </li></ul></ul></ul><ul><ul><li>Raising and lowering wings is achieved by alternate contraction of extensor muscles and flexor muscles. </li></ul></ul>
  36. 39. Modes of Animal Locomotion <ul><li>In some insect orders, flight muscles are not attached to the wings, but rather to the stiff wall of the thorax. </li></ul>
  37. 40. Summary <ul><li>Characteristics of Epithelial Tissue </li></ul><ul><li>Tissue Types </li></ul><ul><li>Types of Skeletons </li></ul><ul><li>The Structure of Bone </li></ul><ul><li>Types of Joints </li></ul><ul><li>Actions of Skeletal Muscles </li></ul><ul><li>Sliding Filament Mechanism of Contraction </li></ul><ul><li>Control of Muscle Contraction </li></ul><ul><li>Types of Muscle Fibers </li></ul><ul><li>Modes of Animal Locomotion </li></ul>
  38. 41. Muscle Tissue Types <ul><li>Smooth Muscle </li></ul><ul><li>Striated Muscle </li></ul><ul><li>Skeletal </li></ul><ul><li>Cardiac </li></ul>
  39. 43. Striated Muscle <ul><li>Skeletal </li></ul><ul><li>Cardiac </li></ul>
  40. 44. Skeletal Muscle