musculoskeletal lecture

Download Musculoskeletal Lecture

Post on 06-May-2015



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  • 1.Locomotion Skeletal and Muscular Systems
    • Movement is based on Muscles acting on a rigid skeleton
  • All animals employ the use of muscles

2. Types of Skeletons

    • Hydrostatic
    • Fluid filled cavity encircled by muscle fibers
    • Soft-bodied invertebrates
    • Exoskeleton
    • Body encased in hard shell chitin
    • most be shed for growth
    • limits body size as exoskeleton has to grow increasingly thicker and heavier
    • Endoskeleton
    • rigid internal skeleton of bone

3. Types of Skeletons

  • Endoskeletons- rigid internal skeleton to which muscles are attached
    • composed of cartilage or bone
    • vertebrate skeleton
      • axial skeleton - forms axis of body and supports organs of the head, neck, and chest
      • appendicular skeleton - includes bones of the limbs, pectoral and pelvic girdles

4. Exoskeleton and Endoskeleton 5. Skeleton

  • Functions
  • Homeostatic
    • Ca +and P +reservoir
  • Biomechanical
    • Attachment for muscles
    • Protective covering brain and spinal cord
  • Overview
  • Connective Tissue
    • Extracellular matrix with collagen fibers (flexible) impregnated with crystals of Calcium phosphate (rigidity)
  • Dynamic reconstruction

6. Bone Tissue Structure

  • Consists of Haversian System
    • Run length of bone
    • Nerves/blood
  • Osteoblasts - matrix
  • Osteocytes encased
  • Osteoclast - breakdown
  • Concentric lamellae
    • Around canal
  • Lacunae -
  • Canaliculi

7. Classification of Joints (articulations)

  • Joints places where 2 bones are attached
  • Immovable joints dense connective tissue - littlemovement - sutures
  • Slightly movable joints held together by cartilage
  • Some flexibility not much (intervertebral andsymphyses)
  • Freely movable
  • Synovial Joints
  • Capsule with
  • fluid
  • Cartilage end caps

8. Types of Joints 9. Types of Joints 10. Types of Joints 11. Levers for movement

  • Muscles attach to bone to allow movement contraction = movement
  • Origin nonmoving
  • Insertion moving
  • Attach via tendons
  • Muscles oppose each other Antagonistic
  • Muscles that cause the same action synergists
  • Isotonic contraction- muscle and all fibers shorten in length thus force of contraction remains relatively constant
  • Isometric contraction- tension is absorbed by tendons and other elastic tissue, and muscle does not change in length

12. Flexor and Extensor Muscles 13. MuscleStructure

  • Muscle
  • Muscle fascicle
  • Muscle fibers = cell
  • Myofibrils
  • Thick and thin myofilaments
  • Myosin and Actin

14. Muscle Structure (Contd)

  • Striated due to dark
  • and light bands
  • Pattern = organization of myofilaments
  • Repeating structure
  • Sarcomere
  • Dark bands = A myosin
  • Light bands = I actin
  • Z line = actin attachment
  • H zone = myosin only

15. Sliding Filament Mechanism Mechanism of muscle contraction No shortening - sliding 16. 17. The Players 18. muscle relaxed myosin heads cocked unable toBind to actin due to sites blocked by protein -tropomyosin In order to contract tropomyosin must be moved to exposebinding sites on actin Requires a regulatory protein troponin troponin binds totropomyosin 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 19. 20. 21. ATP is required

  • Rigor mortis body not make ATP (DEAD) cross-bridges cannot be broken

22. What causes sliding?

  • Nervous system
  • involvement
  • When stimulated,
  • electrical impulse
  • travels down
  • T-tubules
  • Causes sarcoplasmic reticulum to release
  • Ca++

23. Control of Muscle Contraction

  • Nerves stimulate contraction
    • Somatic motor neurons stimulate skeletal muscles.
      • Axon extends from neuron cell body and branches to make synapses with a number of muscle fibers.

24. Control of Muscle Contraction

  • Somatic motor neuron stimulates contraction:
    • releasing acetylcholine neurotransmitter (ACh).
    • impulses spread along membrane and carried into the muscle fibers through the T tubules
    • T tubules conduct impulse toward the sarcoplasmic reticulum, which releases Ca ++
  • Excitation-contraction coupling

25. Control of Muscle Contraction

  • Motor units and recruitment
    • set of muscle fibers innervated by all axonal branches is defined as a motor unit
      • division of muscle into motor units allows muscles strength of contraction to be finely graded
        • most muscles contain motor units in a variety of sizes
      • recruitment- nervous systems use of increased numbers and sizes of motor units to produce a stronger contraction

26. Number and Size of Motor Units 27. Types of Muscle Fibers

  • Muscle fiber twitches
    • muscle stimulated with a single electric shock
      • A second electrical shock delivered immediately after the first will produce a second twitch that may partially piggyback on the first ( summation ).
        • At a particular frequency of stimulation, there is no visible relaxation between successive twitches ( tetanus ).

28. Summation 29. Types of Muscle Fibers

  • Skeletal muscle fibers can be divided on the basis of their contraction speed:
    • Type I slow-twitch fibers
      • rich capillary supply, numerous mitochondria, and high concentration of myoglobin pigment (red fibers)
    • Type II fast-twitch fibers
      • fewer capillaries and mitochondria and not as much myoglobin (white fibers)

30. Types of Muscle Fibers

  • Muscle metabolism during rest and exercise
    • Skeletal muscles at rest obtain energy from aerobic respiration of fatty acids.
      • Skeletal muscles respire anaerobically for the first 45-90 seconds of moderate to heavy exercise.
      • Maximum rate of oxygen consumption in the body is called maximal uptake or aerobic capacity.

31. Types of Muscle Fibers

  • Muscle fatigue and physical training
    • Muscle fatigue refers to the use-dependent decrease in the ability of a muscle to generate force.
      • usually correlated with the production of lactic acid by the exercising muscles
        • also related to depletion of muscle glycogen

32. Types of Muscle Fibers

  • Endurance-trained athletes have a high aerobic capacity, and thus can perform more exercise before lactic acid production and glycogen depletion cause muscle fatigue.
    • Weight training (resistance training) causes muscle fibers to become thicker as a result of increased size and number of myofibrils.
      • cause skeletal muscles to grow byhypertrophy

33. Modes of Animal Locomotion

  • 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).

34. Modes of Animal Locomotion

  • Locomotion in water
    • Buoyancy reduces the influence of gravity.
      • The primary force r


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