1.3 neuromuscular system

Question 1

State the 3 main types of muscle fibre

Answer 1

• slow oxidative (type 1)
• fast oxidative glycolytic (type IIa)
• fast glycolytic (type IIx)

Question 2

State the structural characteristics of type I muscle fibres

Answer 2

• small motor neurone size
• high mitochondrial density
• high myoglobin content
• high capillary density

Question 3

State the functional characteristics of type I muscle fibres

Answer 3

• slow contraction speed
• low fatigability/high resistance to fatigue
• low glycolytic enzyme activity
• high aerobic capacity
• low anaerobic capacity
• slow motor neurone conduction capacity
• low force produced

Question 4

State the structural characteristics of type IIa muscle fibres

Answer 4

• large motor neurone size
• medium mitochondrial density
• medium capillary density
• medium myoglobin content

Question 5

State the functional characteristics of type IIa muscle fibres

Answer 5

• fast contraction speed
• medium fatigability
• high glycolytic enzyme activity
• fast motor neurone conduction capacity
• high force produced
• medium aerobic capacity
• high anaerobic capacity

Question 6

State the structural characteristics of type IIx muscle fibres

Answer 6

• large motor neurone size
• low mitochondrial density
• low capillary density
• low myoglobin content

Question 7

State the functional characteristics of type IIx muscle fibres

Answer 7

• fast contraction speed
• high fatigability
• very high anaerobic capacity
• low aerobic capacity
• very high glycolytic enzyme activity
• high force produced
• fast motor neurone conduction capacity

Question 8

Define hypertrophy

Answer 8

where the muscle has become bigger and stronger

Question 9

What is a motor unit?

Answer 9

A motor neurone and its muscle fibres

Question 10

What are motor neurones?

Answer 10

Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles

Question 11

What is a neuromuscular joint?

Answer 11

Where the motor neurone and muscle fibre meet

Question 12

Define all or none law

Answer 12

where a sequence of impulses has to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract (must be equal to or more than the threshold) if not, none of them contract

Question 13

What is wave summation?

Answer 13

Where there is repeated nerve impulse with no time to relax so a smooth, sustained contraction occurs rather than twitches

Question 14

What must be present for a muscle to contract?

Answer 14

calcium

Question 15

What is a tetanic contraction?

Answer 15

A sustained muscle contraction caused by a series of fast repeating stimuli (calcium is released each time the nerve impulse reaches the cell and it is needed for a muscle to contract)

Question 16

What is spatial summation?

Answer 16

When the strength of contraction changes by altering the number and size of the muscle’s motor units, it occurs when impulses are received at the same time at different places on the neurone

Question 17

What is PNF?

Answer 17

proprioceptive neuromuscular facilitation- an advanced stretching technique

Question 18

What are the 2 proprioceptors used in PNF?

Answer 18

muscle spindles and golgi tendon organs

Question 19

What are muscle spindles?

Answer 19

these detect how far and how fast a muscle is being stretched and produce the stretch reflex

Question 20

What are golgi tendon organs?

Answer 20

these are activated when there is tension in a muscle

Question 21

What is the purpose of the stretch reflex produced by muscle spindles?

Answer 21

to prevent over-stretching and reduce the risk of injury

Question 22

Define autogenic inhibition

Answer 22

when there is a sudden relaxation of the muscle in response to high tension. the receptors involved in this process are golgi tendon organs

Question 23

What’s an isometric contraction?

Answer 23

when there is tension in a muscle but not visible movement