Movement

• Musculoskeletal system

  Roles: movement, support, protection
• Bone

  • Rigid nature supports and protects organs
  • Provides structure for muscles to pull and create movement
• Movement

  1. Muscles contract

  2. Muscles pull on tendons

  3. Tendons attached to bones

  4. Bones act as levers
• Antagonistic muscles

  Muscles that work in opposite directions to produce controlled movement
• Antagonistic muscles in insect leg

  • Extensor tibiae muscle (extends leg)
  • Flexor tibiae muscle (flexes leg)
• Skeletal muscles work in antagonistic pairs
• Synovial joints allow certain movements but not others
• Skeletal muscle fibres

  • Multinucleate
  • Contain specialized endoplasmic reticulum
• Muscle fibres

  • Contain many myofibrils
• Myofibril

  Basic rod-like contractile unit within a muscle cell
• Sarcomere

  Contractile unit of a myofibril
• Muscle contraction

  Sliding of actin and myosin filaments
• ATP hydrolysis

  Necessary for filaments to slide
• Calcium ions, tropomyosin, troponin

  Control muscle contractions
• Fluorescent calcium indicators and dyes used to study rapid muscle contraction
• Ashley and Ridgway first studied role of calcium ions in muscle contraction using aequorin