Topic 11.2

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


11.2.U1 Bones and exoskeletons provide anchorage for muscles and act as levers

Diagram of bones as levers

11.2.U2 Synovial joints allow certain movements but not others

Types of synovial joints explained

11.2.U3 Movement of the body requires muscles to work in antagonistic pairs

Antagonistic muscle diagram

11.2.U4 Skeletal muscle fibres are multinucleate and contain specialized endoplasmic reticulum

Diagram of a muscle fibre

11.2.U5 Muscle fibers contain many myofibrils

Structure of a myofibril

11.2.U6 Each myofibril is made up of contractile sacromeres

Structure of a sacromere diagram

11.2.U7 The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments

Relaxed and contracted muscle diagram

11.2.U8 ATP hydrolysis and cross bridge formation are necessary for the filaments to slide

Diagram of cross-bridge cycling in muscle

11.2.U9 Calcium ions in the proteins tropomyosin and troponin control muscle contractions

Diagram of role of calcium ions in muscle contraction


11.2.A1 Antagonistic pairs of muscles in an insect leg

Diagram of antagonistic muscles in an insect leg


11.2.S1 Annotation of a diagram of the human elbow

Place your mouse pointer on the diagram to view labelled structures and functions.

Diagram of elbow joint

11.2.S2 Drawing labeled diagrams of the structure of the sacromere

Placing your mouse pointer on the figure below will show the actin and myosin myofilaments.

Click on the image to show the z-line, dark and light bands and then double click on the image to return to the actin and myosin filaments.

Diagram of sacromere structures

11.2.S3 Analysis of an electron micrograph to find the state of contraction of muscle fibers

Contracted striated muscle
Show explanation for relaxed or contracted | Hide explanation for relaxed or contracted
Sliding filament theory
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