Movement 11.2 HL

This topic covers the basic structure of joints and the role of bones and exoskeletons in movement before looking in detail at the structure of sarcomeres in skeletal muscles and the processes of the sliding filament theory. Practical techniques in the topic include measuring sarcomere length and labelling diagrams of synovial joints.

Key concepts

Learn and test your biological vocabulary using these 11.2 Movement topic flash cards

Essentials

These slides summarise the essential understanding and skills in the topic Movement 11.2. 
They contain short explanations in text and images - great revision.

Read the slides and look up any words or details you find difficult to understand.

Summary

Summary list for 11.2 Movement

Skeletons and muscles

  • Bones and exoskeletons (e.g. insect legs) provide anchorage for muscles and act as levers.
  • Synovial joints allow certain movements but not others.
  • Muscles work in antagonistic pairs.

Muscle contraction

  • Skeletal muscle fibres are multi-nucleate and contain
    • specialised endoplasmic reticulum.
    • many myofibrils.
    • made up of contractile sarcomeres.
  • The sliding of actin and myosin filaments causes contraction.
  • Contraction requires ATP hydrolysis and cross bridge formation
  • Calcium ions and the proteins tropomyosin and troponin control muscle contractions.

Skills & applications

  • Know how to annotate a diagram of the human elbow. Include cartilage, synovial fluid, joint capsule, named bones and named antagonistic muscles.
  • The ability to draw labelled diagrams of the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands.
  • The ability to find the state of contraction of muscle fibres in electron micrographs,
  • Experience of measurement of the length of sarcomeres using calibration of the eyepiece scale of the microscope.

Mindmaps

This diagram summaries the main sections of topic 11.2 about movement.
Test if you can draw something like these concept maps from memory.

Exam style questions

Understanding the structure of sarcomeres and their dark and light bands is an important skill from this topic.

Answer the question below on a piece of paper, then check your answer against the model answer below.

Grasshoppers jump using contraction of muscles in their legs. Explain the structure of myofibrils in muscles and the contraction of sarcomeres in the myofibrils. [8]

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Extra exam question on synovial joints.    Click to open.

The understanding of the functions of the parts of a synovial joint and how joints allow and limit limb movement is an important concept.

Outline the role of the synovial joint in the movement of a limb. (6 marks)


Hint: Link the structure of the synovial joint to limb movement.
Click on the "+" icon to see a model answer.

Extra exam question on  ATP and skeletal muscle contraction.    Click to open.

The role of ATP in the interaction of actin and myosin to cause muscle contraction is an important concept.

Outline the role of ATP in the contraction of skeletal muscle. (4 marks)


Hint: Outline expects the important points. They need to be in the correct order to gain full marks.

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Extra exam question on the role of the musculoskeletal system       Click to open.

The musculoskeletal system has several roles, you need to know these roles and be able to give an example of each role.

Answer the question on paper and compare your answer to the model answer.

List, with an example for each, the roles of the musculoskeletal system in a mammal (3 marks).





Hint - make a numbered list and give an example next to the role.
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Test yourself

Multiple Choice questions

This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.


START QUIZ!

Drag and drop activities

Antagonistic muscles of the human forearm.

Test your ability to construct biological explanations using the drag and drop questions below.

Drag and drop the correct term into the gap to describe how the antagonistic muscles of the human forearm generate movement.

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relaxes increases biceps direction extends antagonistic tension

Muscles can only create when they contract, so pairs of muscles are needed to provide the force to move a limb in either .

Skeletal muscles work in pairs. In the human forearm, the muscle flexes (bends) the forearm and the antagonist, the triceps (straightens) the forearm.

When one of the antagonistic pair contracts, the other reflexively and in length.

Muscles contract and shorten to provide tension (force). They cannot lengthen except by the contraction of the antagonist.


Just for fun

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