11.2 - Movement

Question 1

Levers

Answer 1

Exoskeletons and bones act as levers by anchoring muscles to facilitate movement changing size and direction of forces

types of levers:

• 1st class lever: effort - pivot - resultant
• 2nd class: pivot - resultant - effort
• 3rd class: pivot - effort - resultant

Question 2

movements of joints

Answer 2

point where bones meet allowing articulation which is the movement of connected bones in relation to each other

types of joints and their movements:

• hinge joint: flexion and extension
• pivot joint: added movement when flexed
• socket joint: flexion, extension, abduction (sideways up), adduction (sideways down), outwards rotation, inwards rotation

Question 3

Skeletal muscles

Answer 3

muscles attached to bones forming an antagonistic pair to produce opposing movement body movements, when one is contracted the other is relaxed

• composed of bundles of muscle fibres which are elongated
  muscle cells composed of many nuclei, sarcoplasmic reticulum,
  and microfibrils surrounded by a sarcolemma
  - sarcolemma is a single plasma membrane surrounds each
  muscle fibre
  - sarcoplasmic reticulum causes the contraction of all muscle
  fibres at once
  - microfibrils are elongated structures made of sarcomas
  - sarcomas are repeated units of light and dark bands
  between z-lines
  - thin actin filaments attached on each side of a z-line
  forming the light band
  - thick myosin filaments with heads (for cross-bridges)
  in the space between z-lines surrounded by actin
  filaments form the dark bands

Question 4

Muscle Contraction

Answer 4

shortening of sarcomere from the pulling of actin from formation of cross-bridges by myosin heads

1. tropomyosin binds to myosin-binding sites on actin when muscle is relaxed
2. Ca2+ is released from sarcoplasmic reticulum when motor neuron signals for contraction
3. Ca2+ binds to troponin which moves tropomyosin from binding-sites
4. myosin heads bind to myosin binding sites on actin forming cross-bridges
5. ATP binds to myosin heads breaking cross bridge
6. ATP hydrolysis provides energy for myosin heads to cock away from the centre of sarcomere
7. myosin heads bind to adjacent binding site on actin forming new cross-bridges away from center
8. stored energy in cocks myosin heads back pulling actin filament towards center of sarcomere shortening it
9. cycle continues
10. when motor neuron signals stop, Ca2+ return to sarcoplasmic reticulum, tropomyosin blocks binding sites on actin

Question 5

Hindleg of grasshopper

Answer 5

jointed appendange with femur - joint - tibia - joint - tarsus attached to flexor and extensor antagonistic muscles for jumping

Flexor muscle (under between femur and tibia): contracts while extensor is relaxed bringing tibia and tarsus closer to femur in a z shape for the preparation of a jump

Extensor muscle (over femur): contracts while flexor relaxes extending tibia propelling force for jumpin

Question 6

Human elbow diagram

Answer 6

bicep: flexes elbow
tricep: extends elbow
humerus bone: attached to bicep and tricep
radius bone: attached to bicep
ulna bone: attached to tricep
joint: point between bones
joint capsule: cover for joints holding synovial fluid and preventing dislocation
synovial fluid: lubricant preventing friction
cartilage: cover absorbing shock and preventing friction and contact between bones