1. 11.2 Muscles and Movement
Topic 11 Human health & physiology

2.  11.2.1 State the roles of bones, ligaments, muscles,
tendons and nerves in human movement.
 11.2.2 Label a diagram of the human elbow joint,
including cartilage, synovial fluid, joint capsule, named
bones and antagonistic muscles (biceps and triceps).
 11.2.3 Outline the functions of the structures in the human
elbow joint named in 11.2.2.
 11.2.4 Compare the movements of the hip joint and the
knee joint.

3.  11.2.5 Describe the structure of striated muscle fibres,
including the myofibrils with light and dark bands,
mitochondria, the sarcoplasmic reticulum, nuclei and the
sarcolemma.
 11.2.6 Draw and label a diagram to show the structure of
a sarcomere, including Z lines, actin filaments, myosin
filaments with heads, and the resultant light and dark
bands.
No other terms for parts of the sarcomere are expected.

4.  11.2.7 Explain how skeletal muscle contracts, including the
release of calcium ions from the sarcoplasmic reticulum, the
formation of cross-bridges, the sliding of actin and myosin
filaments, and the use of ATP to break cross-bridges and re-
set myosin heads.
Details of the roles of troponin and tropomyosin are not expected.
Aim 7: Data logging could be carried out using a grip sensor to
study muscle fatigue and muscle strength.
 11.2.8 Analyse electron micrographs to find the state of
contraction of muscle fibres.
Muscle fibres can be fully relaxed, slightly contracted,
moderately contracted and fully contracted.

5. Locomotion
 Most animals can move from one place to another. This is
called Locomotion.
 Animals show a wide variety of types of locomotion.
 Locomotion is produced by the combined effect of three
parts of the body:
 Nerves
 Muscles
 Bones

6. Nerves, Bones & Muscles
 Nerves:
 These carry impulses from the CNS to stimulate muscles to
contract.
 They stimulate each of the different used in locomotion to
contract at the correct time, so the movement is coordinated.
 Bones:
 Bones provide a firm anchorage for muscles in many animals.
 They also act as levers, changing the size or direction of forces
caused by muscles.
 Junctions between bones are called joints.

7. Nerves, Bones & Muscles
 Ligaments:
 These binds bone to bone.
 Are slightly elastic.
 Preventing dislocation.
 Tendons:
 Bind muscle to bone .
 Non-elastic, transferring full force of muscle contraction to
bone.

8. Nerves, Bones & Muscles
 Muscles:
 When muscles contract they
provide the force needed for
locomotion.
 Muscles only do work when
they contract, so pairs of
muscles are needed to carry
out opposite movements.
 These pairs of muscles are
called antagonistic pairs.
Ref: Advanced Biology, Roberts

9. The Elbow Joint
Ref: IB Biology, Oxford Study Courses

10. The Elbow Joint
 The elbow joint is a good example of how nerves, muscles and
bones work together to make motion.
 The main parts of a synovial joint are:
 Ligaments: binds bone to bone and slightly elastic,
preventing dislocation.
 Tendon: binds muscle to bone and non-elastic,
transferring full force of muscle contraction to bone.
 Joint capsule: encloses the joint cavity preventing leakage of
the synovial fluid.
 Synovial fluid: acts as a lubricant, reducing friction & shock
absorber
 Cartilage: provides a smooth surface for joint movement,
reducing friction where bone surfaces meet.
 Extra point: Reduces friction is important to prevent damage/wear

11. The Elbow Joint
Ref: Biology for the IB Diploma, Allott

12. Antagonistic Muscles in the
Elbow Joint
Ref: Advanced Biology, Kent

13. Hip and Knee joints

14. Comparison: hip and knee joints
Feature Hip Knee
Type Synovial – ball & socket Synovial – hinge
Articulating bones Pelvis & Femur Femur & Tibia
Additional bones None Patella
Articulating surfaces Acetabulum & head of femur Femur & tibia
Femur & patella
Permitted movement Circumduction i.e. circular
(three planes)
Flexion & extension
(one plane)

15. Structure of Skeletal Muscle
 A muscle consists of bundles of multinucleated muscle
fibres (cells), each of which is a bundle of myofibrils.
 Each myofibril is made up of thick and thin filaments.
 Thick myosin filaments
 Thin actin filaments
 The filaments are aligned in contractile units called
Sarcomeres.
 The arrangement of thick and thin filaments appears as
alternating light and dark bands when viewed in an
electron micrograph.

18. Structure of Skeletal Muscle

19. Structure of a Sarcomere

20. Muscle Contraction
 The contraction of muscle is due to the sarcomeres in the
myofibrils becoming shorter.
 This is achieved by the sliding of actin and myosin
filaments over each others.
 This uses ATP.

21. Ref: Biology for the IB Diploma, Allott.

22. Controlling Muscle Contraction
 When a muscle fibre is relaxed, a protein called
tropomyosin blocks the myosin binding sites on actin.
 If a motor neurone stimulates the muscle fibre, calcium
ions are released from the sarcoplasmic reticulum.
 These calcium ions bind to another protein called
troponin..
 Troponin then causes tropomyosin to move, which
exposes the myosin binding sites and allows contraction
to begin.

23. Ref: Advanced Biology, Roberts etal.