Topic 11.2: Movement

Question 1

Movement Systems

Answer 1

1) Skeletal system
2) Muscular system
3) Nervous system

Question 2

Skeletal system

Answer 2

Consists of bones that:

1) Act as levers
2) Provide a structure for the muscles to pull

Question 3

Muscular system

Answer 3

Muscles deliver the force required to move one bone in relation to another

Question 4

Nervous system

Answer 4

Delivers signals to the muscles which cause them to contract and create movement

Question 5

Skeletons

Answer 5

Endoskeletons - Consist of numerous bones

Exoskeletons - Comprised of connected segments

Question 6

Ligaments | Tendons

Answer 6

Tendon (BoTtom) - Bone to muscle

Ligament (BLob) - Bone to bone

Question 7

Synovial joints

Answer 7

Capsules surrounding articulating bone surfaces that allow for certain movements but not others

Question 8

Synovial joint components

Answer 8

1) Joint capsule
2) Cartilage
3) Synovial fluid

Question 9

Joint capsule

Answer 9

Seals the joint space

Provides stability by restricting the range of possible movements

Question 10

Cartilage

Answer 10

Lines the bone surface

1) Facilitate smoother movement
2) Absorbing shock and distributing load

Question 11

Synovial fluid

Answer 11

Provides lubrication, oxygen, and nutrition to the cartilage

Question 12

Hinge joint

Answer 12

1) It is capable of angular movement in one direction (i.e. flexion and extension)
2) A small amount of rotation may be possible

Question 13

Elbow Joint Structures

Answer 13

1) Humerus - Anchors muscle (Muscle origin)
2) Radius - Acts as a forearm lever for biceps
3) Ulna - Acts as a forearm lever for triceps
4) Biceps - Bends the forearm (Flexor)
5) Triceps - Straightens the forearm (Extensor)
6) Joint capsule - Seals joint space and limits range of movements
7) Synovial fluid - Provides food, O2, and lubrication
8) Cartilage - Allows smooth movement, absorbs shock, and distributes load.

Question 14

Human elbow

Answer 14

Example of a hinge joint

• It is capable of angular movement (flexion / extension)

Question 15

Antagonistic pairs of skeletal muscles

Answer 15

When one contracts, the other relaxes to enable opposing movements (Flexion / Extension)

Question 16

Antagonistic pairs of muscles in an insect leg

Answer 16

1) When the flexor muscle contracts, the extensor muscle relaxes and the tibia and femur are brought closer together
2) When the extensor muscle contracts, the flexor muscle relaxes and the tibia is pushed away from the femur

Question 17

Organisation of Skeletal Muscles

Answer 17

1) Muscles -> Muscular bundles (surrounded perimysium)
2) Muscular bundle -> Muscle fibres (Muscle cells)
3) Muscle fibres -> myofibrils (Muscular contraction)
4) Myofibrils -> Sarcomeres (Single contractile unit)

Question 18

Muscle Fibre Structure

Answer 18

1) Multinucleate (Fusion of individual muscle)
2) Large number of mitochondria (muscle contraction requires ATP hydrolysis)
3) Sarcoplasmic reticulum (Stores calcium ions)
4) Tubular myofibrils made up of actin and myosin
5) Continuous membrane surrounding the muscle fibre sarcolemma (contains invaginations called T tubule)

Question 19

Sarcomeres

Answer 19

Repeating contractile units of myofibrils

1) Made up of myofilaments (actin + myosin)
2) Myosin has protruding heads that bind to actin

Question 20

Appearance of sarcomere in electron micrographs

Answer 20

1) A band - The centre = darker (Actin/Myosin)
2) I band - The peripheries of the sarcomere = lighter (Actin)
3) H zone - Lighter central region of the dark A band (Myosin)

Question 21

Muscle contraction electron micrographs

Answer 21

Actin filaments slide along the myosin, reducing the length of the lighter I bands

Question 22

Diagram of a Sarcomere

Answer 22

1) Myosin (Thick myofilament)
2) Actin (Thin myofilament)
3) Z disc (Hold the myofilaments in place)

Question 23

Process of muscular contraction

Answer 23

1) Depolarisation and calcium ion release
2) Actin and myosin cross-bridge formation
3) Sliding mechanism of actin and myosin filaments
4) Sarcomere shortening (muscle contraction)

Question 24

Depolarisation and calcium ion release

Answer 24

1) Motor neurons release acetylcholine (neurotransmitter)

2) This triggers sarcolemma depolarisation, causing Ca+2 to be released from the sarcoplasmic reticulum

Question 25

Actin and myosin cross-bridge formation

Answer 25

1) Ca+2 bind to a complex (troponin/tropomyosin) that blocks actin from binding with the myosin heads
2) Ca+2 displace this complex, allowing the actin and myosin heads to form a cross-bridge

Question 26

Sliding Mechanism of Actin and Myosin

Answer 26

1) ATP binds to myosin heads and breaks the cross-bridge
2) ATP hydrolysis causes myosin heads to swivel and slide along the actin fibre – this shortens the sarcomere length
3) Via repeated ATP hydrolysis, skeletal muscles contract

Question 27

Sarcomere shortening

Answer 27

1) The repeated reorientation of the myosin heads drags the actin filaments along the length of the myosin
2) As the individual sarcomeres become shorter in length, the muscle fibres as a whole contracts