F215:04:07 Co-ordinated movement

Question 1

How are voluntary muscles attached to the bones of the skeleton?

Answer 1

by tendons so that the contraction of the muscle moves the bones at the joins

Question 2

What are tendons made of?

Answer 2

tough, inelastic collagen which is continuous with the muscle and the periosteum

Question 3

What is periosteum?

Answer 3

the connective tissues covering the bone

Question 4

Why does the movement of a bone require the co-ordinated action of at least 2 muscles?

Answer 4

As muscles are only capable of producing a force when they contract
So one muscle contracts, the other muscle in the pair must relax to allow for smooth movement
But the movement of bones at many joints require a wider range of action and is under the control of groups of muscles called synergists

Question 5

What are muscles that work in pairs opposite each other described as?

Answer 5

antagonistic

Question 6

What are synergists?

Answer 6

a group of muscles that control the wider range of actions undergone by some joints

Question 7

Give an example of a synovial joint

Answer 7

The elbow

Question 8

What are the names of the 3 bones in the arm?

Answer 8

Humerus
Radius
Ulna

Question 9

Which are the two bones in your forearm?

Answer 9

radius and ulner

radius in line with thumb)

Question 10

What are the two muscles in the arm?

Answer 10

Tricep and bicep

Question 11

When are synovial joints needed?

Answer 11

where a large degree of movement is required

Question 12

what eases the movement at a synovial joint?

Answer 12

synovial fluid which acts as a lubricant

Cartilage- pads where the bones meet to reduce the friction

Question 13

Describe the elbow

Answer 13

There is:
catilage which pads where the bones meet to reduce friction
synovial membrane- which produces synovial fluid
Synovial fluid which lubricates the joint
Ligament- which holds bones together to prevent dislocation

Question 14

Describe the operation of the neuromuscular junction

Answer 14

1. impulses arriving at the neuromuscular junction causes vesicles to fuse with the pre-synaptic membrane and release acetylcholine into the gap
2. Acetylcholine binds to receptors on the muscle fibre membrane causing depolarisation
3. Depolarisation wave travels down tubules (T system)
4. T syste depolarisation leads to Ca2+ release from stores in sarcoplasmic reiculum
5. Ca2+ binds to proteins in the muscle which leads to contraction
6. Acetylcholinesterase in the gap rapidly breaks down acetylcholine so contraction only occurs when impulses arrive continuously

Question 15

What are tubules also known as?

Answer 15

T system

Question 16

What does acetylcholinesterase do?

Answer 16

breaks down acetylcholine so that contractions only occur when impulses arrive continuously

Question 17

How is Ca2+ involved in the operation of the neuromusclar junction?

Answer 17

It binds to the proteins in the muscle, which leads to contraction

Question 18

What is a neuromuscular junction very similar to?

Answer 18

a synapse

Question 19

Why is it necessary for the brain to control the strength of contractions?

Answer 19

As many motor neurones stimulate a single muscle

Question 20

What is a neuromuscular junction?

Answer 20

a specialised synapse that occurs at the end of a motor neurone where it meets the muscle fibre. Release of acetylcholine, following the depolarisation at the neuromuscular junction, stimulates contraction of the muscle fibre.

Question 21

What is the end of a motor neurone often known as?

Answer 21

an end plate or motor end plate

Question 22

What is a motor unit?

Answer 22

A cluster of muscle cells which contract because one motor neurone branches to neuromuscular junctions

Question 23

What is gradation of response?

Answer 23

The more motor units stimulated, the greater the force of contraction

Question 24

How are investigations into how the action of whole muscles?

How is the muscle kept alive?

Answer 24

A muscle is attached to spring loaded pins and to a data logger which records contractions following electrical stimulation of the attached nerve
The muscle is kept alive by immersion in a solution of salts known as Ringers solution

Question 25

What is a twitch?

Answer 25

a quick contraction of the muscle followed by immediate relaxation

Question 26

What is the difference if two large separate twitches are applied far apart and close together?

Answer 26

Far enough apart it will create two separate twitches, but if they are close together the response becomes overlapped and is more powerful than a single maximal response (summation)

Question 27

What is the large stimuli give a sustained and powerful contraction?

Answer 27

tetanus

Question 28

How does the brain control all voluntary muscle actions?

Answer 28

By setting the frequency of impulses at a level to achieve controlled contraction and relaxation in antagonistic muscles

Question 29

Describe tetanus

Answer 29

Multiple stimuli leads to tetanus

But eventually the muscle will fatigue and it reduces the level of contraction

Question 30

A motor unit can consist of between 3 and 200 muscle cells. Suggest what types of muscles have many motor units, eah stimulating very few muscle fibres

Answer 30

Fine controls such as that achieved by muscles that control the motor movements of fingers requires many motor units, each with relatively few muscles cells
This allows the greatest gradation of response

Question 31

Explain why the elbow joint is described as a hinge joint

Answer 31

The movement of joints operates in one plane only. such as the opening of a door around a hinge

Question 32

Name the similarities between a neuromusclar junction and a synpase

Answer 32

• Neurotransmitter is loacted in vesicles in the pre-synaptic cytoplasm
• Vesicles release acetylcholine into cleft on stimulation (arrival of an action potential)
• Neurotransmitter diffuses across the gap and binds to post synaptic membrane receptor
• Binding of neurotransmitter results in opening of sodium ion channels and depolarisation of the post synaptic membrane
• Enzymes present to degrade neurotransmitter to avoid continual stimulation of the post synaptic membrane

Question 33

Name the differences between a neuromusclar junction and a synpase

Answer 33

S: Neurone to neurone
NMJ: Neurone to sarcomere
S: Post synaptic stimulation leads to action potential in postsynaptic neurone
NMJ: Post synaptic stimulation leads to depolarisation of the sarcomella (muscle contraction)
S: Synaptic knob tends to be smooth and rounded
NMJ: End plate has the appearance of microvilli and is flattened up to microfibre

Question 34

What is a sarcomere?

Answer 34

a muscle

Question 35

Describe the appearance of an end plate

Answer 35

End plate has the appearance of microvilli and is flattened up to microfibre