11.2 Movement

Essential idea: The roles of the musculoskeletal system are movement, support and protection.

The rigid nature of bone both supports and protects organs within the body. It also gives a structure for muscles to pull, by their contraction, to create movement.

Understandings:

  • Bones and exoskeletons provide anchorage for muscles and act as levers
  • Synovial joints allow certain movements but not others
  • Movement of the body requires muscles to work in antagonistic pairs
  • Skeletal muscle fibres are multinucleate and contain specialised endoplasmic reticulum
  • Muscle fibres contain many myofibrils
  • Each myofibril is made up of contractile sarcomeres
  • The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments
  • ATP hydrolysis and cross bridge formation are necessary for the filaments to slide
  • Calcium ions and the proteins tropomyosin and troponin control muscle contractions


Applications:

  • Antagonistic pairs of muscles in an insect leg

Skills:

  • Annotation of a diagram of the human elbow
  • Drawing labelled diagrams of the structure of a sarcomere
  • Analysis of electron micrographs to find the state of contraction of muscle fibres


Nature of science

Developments in scientific research follow improvements in apparatus - fluorescent calcium ions have been used to study the cyclic interactions in muscle contraction.

Introductory Video

Powerpoint

11.2 Movement.pptx

Useful Video Clips

Muscles and Joints (Part 3) (IB Biology).mp4

Unit Summary Questions

11.2 Movement Notes.pdf