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CAS Biology 11.2 Muscles and Movement

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CAS Biology 11.2 Muscles and Movement

  1. 1. 11.2 MUSCLES & MOVEMENT IB BIOLOGY
  2. 2. MOVEMENT: THE HUMAN MACHINE • Joints • Bones • Nerves • Muscles • Tendons • Ligaments
  3. 3. THE ELBOW
  4. 4. THE ELBOW • Biceps – bends the arm (flexor) • Triceps – straightens the arm (extensor) • Humerus – anchors muscle (muscle origin) • Radius/Ulna – acts as forearm levers (muscle insertion) • Radius acts as a lever for the biceps • Ulna acts as a lever for the triceps • Cartilage – allows easy movement (smooth surface), absorbs shock and distributes load • Synovial fluid – provides food, oxygen, and lubrication to the cartilage • Joint capsule – seals the joint space and provides passive stability by limiting range of movement
  5. 5. KNEE JOINT VS HIP JOINT
  6. 6. KNEE JOINT VS HIP JOINT Similarities: - Both are synovial joints - Both are involved in the movement of the leg Differences:
  7. 7. MUSCLE STRUCTURE sarcomeres < myofibrils < muscle fibers = MUSCLES muscle fibers – long multinucleate cells Within each muscle fiber are cylindrical structures called myofibrils Myofibrils consist of repeating units called sarcomeres, which have light and dark bands
  8. 8. STRIATED MUSCLE FIBER
  9. 9. STRIATED MUSCLE FIBER Sarcolemma – specialized plasma membrane Sarcoplasmic reticulum – specialized endoplasmic reticulum designed for muscle contraction (contains high Ca2+) Myofibrils – tubular fibers divided into sections called sarcomeres, and made up of two different myofilaments (actin & myosin) Mitochondria – large numbers in order to produce enough ATP for muscle contraction
  10. 10. STRIATED MUSCLE FIBER
  11. 11. SARCOMERES
  12. 12. SARCOMERES
  13. 13. SARCOMERES H zone – area only occupied by the thick filaments (myosin) I bands (light) – regions occupied by only thin filaments (actin) A bands (dark) - are the region occupied by both filaments (overlap) Z lines – represent the extremeties of a single sarcomere
  14. 14. SARCOMERES H zone – area only occupied by the thick filaments (myosin) I bands (light) – regions occupied by only thin filaments (actin) A bands (dark) - are the region occupied by both filaments (overlap) Z lines – represent the extremeties of a single sarcomere
  15. 15. SARCOMERES I band A band H-zone
  16. 16. SARCOMERES H-zone I band A band I band
  17. 17. SARCOMERE CONTRACTION
  18. 18. SARCOMERE CONTRACTION
  19. 19. SARCOMERE CONTRACTION What do you expect to happen to the: H zone? A band? I band?
  20. 20. SARCOMERE CONTRACTION
  21. 21. SARCOMERE CONTRACTION
  22. 22. SARCOMERE CONTRACTION Four Stages of Cross Bridge Cycle 1) Cross Bridge Formation 2) Power Stroke 3) Cross Bridge Detachment 4) Reactivation of Myosin Head

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