11. Animal Physiology : 11.2 Movement

Question 1

Explain the movement in insects and crustaceans.

Answer 1

• muscles attached to exoskeleton (made of chitin)
• hind legs for jumping
• muscles of legs work antagonistically
• extensor muscle is inner muscle and flexor is outer

Question 2

What are the steps of jumping in insects?

Answer 2

Steps of jumping insects:

1. Flexor contracts, extensor relax, tibia flexes
2. Extensor contracts, flexor relax, tibia extends
3. Jump as a result of tibia extension

Question 3

What are biceps and triceps located and what are their functions?

Answer 3

Bicep: located above humerus and bend forearm

Tricep: below humerus and extends forearm

Question 4

What makes movement possible?

Answer 4

Made possible because of cartilage that covers the end of the bone and prevents friction

Question 5

What is the bone made up of?

Answer 5

Calcium phosphate, collagen, elastic protein

Question 6

What are synovial joints?

Answer 6

Joints that possess a synovial cavity between two bones.

• cavity filled with synovial fluid reduces friction at the joint and allows it to move more freely
• prevents dislocation, reduces friction

Question 7

What happens in dislocation?

Answer 7

An injury to a joint where the bone ends are forced from normal positions

Question 8

What is a sarcolemma?

Answer 8

The cell membrane of the striated muscle fibre cell

Question 9

What are skeletal muscle cells?

Answer 9

Result of the fusion of many embryonic muscle cells. can be more than 1 cm long.

Question 10

What is the sarcoplasmic reticulum?

Answer 10

• Membrane bound structure in muscle cells
• Stores calcium
• Surrounds each myofibril and allow it to convey a signal to all parts of the muscle to contract or relax

Question 11

What are sarcomeres and how are they formed?

Answer 11

Functional unit of the myofibrils and contain myosin and actin filaments

The overlapping and forming of cross-bridges of myosin and actin filaments causes contraction in muscles

Question 12

What does the sliding filament theory state?

Answer 12

States that the length of myosin is the same in contraction and relax muscles

Question 13

What causes muscles to become short?

Answer 13

The actin and myosin slides over each other to shorten the length
Actin slides over myosin and moves inwards towards the centre of the sarcomere
This makes the length of sarcomeres short and thus, the entire muscle becomes short

Question 14

Explain the steps involved in sarcomere contraction.

Answer 14

1. New ATP attaches to myosin head, cross bridge detaches
2. ATP into ADP and P1, cocking of the myosin head occurs (cocking: raising something to get ready for further process)
3. A cross-bridge forms and myosin head + actin
4. Myosin head bends as it pulls on actin filament and slides towards the M line

Question 15

List 4 factors of sarcomere contraction.

Answer 15

• ATP hydrolysis and cross bridge formation
• Calcium ions
• Proteins tropomyosin
• Troponin

Question 16

What happens when a muscle receives a neuronal impulse to contract?

Answer 16

• calcium ions are released from sarcoplasmic reticulum
• ions bind to troponin and forces tropomyosin to move
• this exposes the actin binding sites
• myosin heads can make a cross bridge and pivot the actin filament towards the sarcomere.
• cross bridges help with contraction