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

• Outline answer to each objective statement for topic 11.2 (coming soon)
• Quizlet study set for this topic (coming soon)​

At SHS, Topic 11.2 is taught in the following class unit(s):

• Muscles and Movement​

Statements & Objectives:

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

• State the function of bones and exoskeletons.
• Contrast bones with exoskeletons.
• Identify the fulcrum, effort force and resultant force in the motion of the spine and the grasshopper leg.
• Determine the class of motion of a lever.

11.2.U2  Movement of the body requires muscles to work in antagonistic pairs.

• Define antagonistic pairs in relation to muscle movement.
• State an example of an antagonistic pair of muscles.

11.2.U3  Synovial joints allow certain movements but not others.

• Compare the motion of hinge joints with the motion of a ball and socket joint.
• Outline motion of the human knee, shoulder and hip in terms of flexion, extension, rotation, abduction and adduction.

11.2.U4  Skeletal muscles fibres are multinucleated and contain specialized endoplasmic reticulum.

• List three types of muscle tissue found in the human body.
• Label a diagram of a muscle fibre cell, including the sacrolemma, nuclei, sacroplasmic reticulum and mitochondria.

11.2.U5  Muscle fibres contain many myofibrils.

• Outline the relationship between muscles, muscle fibre cells and myofibrils.

11.2.U6  Each myofibrils is made up of contractile sarcomeres.

• Outline the relationship between myofibrils and sacromeres.
• Describe a structure of a sarcomere., including the Zline, thin actin filaments, thick myosin filaments, light band and dark band.​

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

• Explain the sliding-filament mechanism of muscle contraction, including the role of myosin heads, cross bridges and ATP.

11.2.U8  Calcium ions and the proteins tropomyosin and troponin control muscle contractions. 

• Explain the exposure of myosin head binding sites on actin, including the role of the sarcoplasmic reticulum, calcium, troponin and tropomyosin. 

11.2.U9  ATP hydrolysis and cross bridge formation are necessary for the filaments to slide.

• List the events that occur during cross-bridge cycles.
• Describe the role of ATP in muscle contraction.

11.2.A1  Antagonistic pairs of muscles in an insect leg.

• Label the tibia, femur, tarsus, flexor muscle and extensor muscle on a diagram of a grasshopper hindlimb.
• Describe the contraction of muscles and movement of hindlimb structures that produces a grasshopper jump.

11.2.S1  Annotations of a diagram of the human elbow.

• Label a diagram of the human elbow inclusive of:  humerus, triceps, biceps, joint capsule, synovial fluid, radius, cartilage and ulna.
• State the function of structures found in the human elbow, including:  humerus, triceps, biceps, joint capsule, synovial fluid, radius, cartilage and ulna.

11.2.S2  Drawing labelled diagrams of the structure of a sarcomere.

• Draw a diagram of the structure of a sarcomere.  
• Label a sarcomere diagram, including Z lines, actin filaments, myosin filaments with heads and the resultant light and dark bands.

11.2.S3  Analysis of electron micrographs to find the state of concentration of muscle fibres.

• Compare a relaxed sarcomere to a contracted sarcomere, referring to Z line distance and size of light bands.
• Determine of a sarcomere is contracted or relaxed given an electron micrograph image.

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

• • Describe the use of fluorescence to study muscle contraction.
  • Explain the bioluminescence observed in muscle contraction studies using calcium sensitive aequorin.
  • Explain the bioluminescence observed in muscle contraction studies using fluorescently tagged myosin molecules.​