11.2 muscles and movement


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11.2 muscles and movement

  1. 1. 11.2 Muscles and Movement Topic 11 Human health & physiology
  2. 2.  11.2.1 State the roles of bones, ligaments, muscles, tendons and nerves in human movement.  11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps).  11.2.3 Outline the functions of the structures in the human elbow joint named in 11.2.2.  11.2.4 Compare the movements of the hip joint and the knee joint.
  3. 3.  11.2.5 Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.  11.2.6 Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands. No other terms for parts of the sarcomere are expected.
  4. 4.  11.2.7 Explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and re- set myosin heads. Details of the roles of troponin and tropomyosin are not expected. Aim 7: Data logging could be carried out using a grip sensor to study muscle fatigue and muscle strength.  11.2.8 Analyse electron micrographs to find the state of contraction of muscle fibres. Muscle fibres can be fully relaxed, slightly contracted, moderately contracted and fully contracted.
  5. 5. Locomotion  Most animals can move from one place to another. This is called Locomotion.  Animals show a wide variety of types of locomotion.  Locomotion is produced by the combined effect of three parts of the body:  Nerves  Muscles  Bones
  6. 6. Nerves, Bones & Muscles  Nerves:  These carry impulses from the CNS to stimulate muscles to contract.  They stimulate each of the different used in locomotion to contract at the correct time, so the movement is coordinated.  Bones:  Bones provide a firm anchorage for muscles in many animals.  They also act as levers, changing the size or direction of forces caused by muscles.  Junctions between bones are called joints.
  7. 7. Nerves, Bones & Muscles  Ligaments:  These binds bone to bone.  Are slightly elastic.  Preventing dislocation.  Tendons:  Bind muscle to bone .  Non-elastic, transferring full force of muscle contraction to bone.
  8. 8. Nerves, Bones & Muscles  Muscles:  When muscles contract they provide the force needed for locomotion.  Muscles only do work when they contract, so pairs of muscles are needed to carry out opposite movements.  These pairs of muscles are called antagonistic pairs. Ref: Advanced Biology, Roberts
  9. 9. The Elbow Joint Ref: IB Biology, Oxford Study Courses
  10. 10. The Elbow Joint  The elbow joint is a good example of how nerves, muscles and bones work together to make motion.  The main parts of a synovial joint are:  Ligaments: binds bone to bone and slightly elastic, preventing dislocation.  Tendon: binds muscle to bone and non-elastic, transferring full force of muscle contraction to bone.  Joint capsule: encloses the joint cavity preventing leakage of the synovial fluid.  Synovial fluid: acts as a lubricant, reducing friction & shock absorber  Cartilage: provides a smooth surface for joint movement, reducing friction where bone surfaces meet.  Extra point: Reduces friction is important to prevent damage/wear
  11. 11. The Elbow Joint Ref: Biology for the IB Diploma, Allott
  12. 12. Antagonistic Muscles in the Elbow Joint Ref: Advanced Biology, Kent
  13. 13. Hip and Knee joints
  14. 14. Comparison: hip and knee joints Feature Hip Knee Type Synovial – ball & socket Synovial – hinge Articulating bones Pelvis & Femur Femur & Tibia Additional bones None Patella Articulating surfaces Acetabulum & head of femur Femur & tibia Femur & patella Permitted movement Circumduction i.e. circular (three planes) Flexion & extension (one plane)
  15. 15. Structure of Skeletal Muscle  A muscle consists of bundles of multinucleated muscle fibres (cells), each of which is a bundle of myofibrils.  Each myofibril is made up of thick and thin filaments.  Thick myosin filaments  Thin actin filaments  The filaments are aligned in contractile units called Sarcomeres.  The arrangement of thick and thin filaments appears as alternating light and dark bands when viewed in an electron micrograph.
  16. 16. Structure of Skeletal Muscle
  17. 17. Structure of a Sarcomere
  18. 18. Muscle Contraction  The contraction of muscle is due to the sarcomeres in the myofibrils becoming shorter.  This is achieved by the sliding of actin and myosin filaments over each others.  This uses ATP.
  19. 19. Ref: Biology for the IB Diploma, Allott.
  20. 20. Controlling Muscle Contraction  When a muscle fibre is relaxed, a protein called tropomyosin blocks the myosin binding sites on actin.  If a motor neurone stimulates the muscle fibre, calcium ions are released from the sarcoplasmic reticulum.  These calcium ions bind to another protein called troponin..  Troponin then causes tropomyosin to move, which exposes the myosin binding sites and allows contraction to begin.
  21. 21. Ref: Advanced Biology, Roberts etal.