BMS03-1018 Muscle Contraction

Question 1

Prime function of muscle

Answer 1

Convert chemical energy into mechanical work

Question 2

How much of lean body mass does the musculoskeleton compromise?

Answer 2

75%

Question 3

What 5 make up protein?

Answer 3

75% water
20% protein - 40% myosin and 20% actin and the rest is tropomyosin etc
5% inorganic salt and other

Question 4

What attaches muscle to bone?

Answer 4

Tendon

Question 5

What are muscle fibres grouped into?

Answer 5

Fascicles

Question 6

How is Ca involved in contraction?

Answer 6

Released from the sarcoplasmic reticulum
Binds to tropomyosin revealing the actin binding site so myosin can bind
ATP then binds and gets hydrolysed pushing the head forwards

Question 7

Which neurotransmitter is used?

Answer 7

Acetylcholine

Question 8

What happens when acetylcholine binds the post?

Answer 8

Na enter triggering an action potential which travels down the T tubules and then makes the sarcoplasmic reticulum release Ca

Question 9

Twitch

Answer 9

Mechanical response to a single electrical impulse

Question 10

What happens from the stimuli?

Answer 10

Electromechanical delay, time to peak tension, peak tension, half relaxation time

Question 11

Tetanus

Answer 11

Mechanical response of multiple stimuli

Question 12

Types of tatanus

Answer 12

Unfused (lots of separate small ones) or fused (makes one stronger one)

Question 13

How long does calcium half removal take?

Answer 13

80ms

Question 14

At what Hz will a tetaus be partially fused and why?

Answer 14

10 as the Ca conc builds up

Question 15

What does high impulse rate permit?

Answer 15

Always high Ca concentration so cross bridge can continue uninterrupted

Question 16

What twitch do type 1 and type 2 muscles have?

Answer 16

1 slow

2 fast

Question 17

How do slow and fast fibres differ?

Answer 17

They reach tetanus at a lower stimulation so they reach maximal force lower

Question 18

Spatial recruitment

Answer 18

Minimal number of motor units needed

Smallest 1
Medium 2a
Largest 2x

Question 19

Temporal recruitment

Answer 19

Same neuron firing lots of times

Question 20

Rate coding

Answer 20

Motor unit firing rate

Question 21

Which muscle types use each recruitment?

Answer 21

Spatial
Large muscles with many fibre types

Temporal
Smaller muscles

Question 22

Which units get fatigued quicker, ones with lots of fibres of few?

Answer 22

Lots

Question 23

What is a large motor unit?

Answer 23

Lots of muscle fibres

Question 24

What are the masticatory muscles?

Answer 24

Masseter

Temporalis

Question 25

What is the structure of masticatory muscles?

Answer 25

Pennate, muscle fibres between tendons

Question 26

Which muscle type dominates?

Answer 26

Type 1

Question 27

What is the motor unit size?

Answer 27

Variable