1.3 - The neuromuscular system

Question 1

define neuromuscular system

Answer 1

where the nervous system and the muscles work together to allow movement

Question 2

effect of the sympathetic nervous system on the body:

Answer 2

prepares the body for exercise

referred to as the ‘fight or flight’ response

Question 3

effect of the parasympathetic nervous system on the body:

Answer 3

relaxes the body

slows the body down

‘rest and relax’

Question 4

what are slow oxidative fibres (type 1)

Answer 4

slower contraction speed

better adapted for lower intensity exercise (e.g long distance running)

produce most of their energy aerobically

Question 5

what are fast oxidative glycolytic fibres (type IIa) ?

Answer 5

fast contraction speed

can generate a greater force of contraction

used for short, intense bursts of effort

produce most energy anaerobically

fatigue quickly (more resistant than IIb)

used for events like 1500m where a longer burst of energy is needed.

Question 6

what are fast glycolytic fibres (type IIb) ?

Answer 6

faster contraction speed (than type IIa)

can generate a greater force of contraction

used for short, intense bursts of effort

produce most energy anaerobically

fatigue quickly

used for highly explosive events ( 100m) where quick, short burst of energy are needed

Question 7

what are characteristics of the twitch fibres?

mention: contraction speed, motor neurone size, force produced, mitochondrial density, myoglobin content, aerobic capacity and anaerobic capacity.

Answer 7

type 1 type IIa type IIb

contraction speed slow fast fast

motor neurone small large large

size

force produced low high high

mitochondrial high medium low

density

myoglobin content high medium low

aerobic capacity very high medium low

anaerobic capacity low high very high

Question 8

define hypertrophy

Answer 8

where the muscle has become bigger and stronger

Question 9

define a motor unit

Answer 9

a motor neurone and its muscle fibres

Question 10

define a motor neurone

Answer 10

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

Question 11

define a neuromuscular junction

Answer 11

where the motor neurone and the muscle fibre meet

Question 12

how do motor units create movement?

Answer 12

the motor neurone transmits nerve impulses to the muscle fibre, creating movement

Question 13

what is the all or none law?

Answer 13

stimulation of muscle fibres must reach the ‘threshold’ in order for them to contract

(all muscle fibres must be stimulated)

(if not, none of them contract)

Question 14

what is a slow twitch motor unit?

Answer 14

used for low intensity activity

e.g jogging, long distance swimming

Question 15

what is a fast twitch motor unit?

Answer 15

when a greater force of contraction is needed

e.g sprinting, power lifting

Question 16

how do you increase the strength of a contraction?

Answer 16

wave summation

spatial summation

Question 17

what is wave summation?

Answer 17

there is a repeated nerve impulse

with no time to relax

so a smooth, sustained contraction occurs

the build up of calcium allows for a forceful contraction (tectonic contraction)

Question 18

what is spacial summation?

Answer 18

when the strength of a contraction changes

by altering the number and size of the muscle’s motor units

e.g jumping for a rebound, lots of large twitch motor units are used in the quadriceps to try and achieve as much height as possible

Question 19

what does PNF stand for?

Answer 19

proprioceptive neuromuscular facilitation

Question 20

what is PNF?

Answer 20

an advanced stretching technique

most effective form of flexibility training for increasing range of motion

Question 21

what are muscle spindles?

Answer 21

they detect how far and fast a muscle is being stretched

and produce the stretch reflex

The stretch reflex prevents over-stretching and reduce the risk of injury

(CNS then sends an impulse back to the muscle, telling it to contract - stretch reflex )

Question 22

what are golgi tendons?

Answer 22

activated when there is tension in a muscle

found between the muscle fibre and tendon

autogenic inhibition:

when muscle contracts isometrically in PNF,

they sense an increase in tension

and send inhibitory signals to the brain (allowing the antagonist muscle to relax and lengthen)

Question 23

Give an example of PNF in practice.

Answer 23

• passive stretch, extending the leg until tension is felt
• muscle spindles detect the stretch
• stretch reflex occurs when it is being stretched too far
• individual isometrically contracts the muscle for 10 seconds with the help of a partner
• golgi tendon organs are sensitive to the tension developed
• they are then activated
• and send inhibitory signals to prevent the muscle spindles from contracting
• this delays the stretch reflex
• leg is lifting again and stretches further (due to antagonistic nature of golgi tendons)

Question 24

define isometric contraction.

Answer 24

where there is tension in a muscle but no visible movement

Question 25

define autogenic inhibition

Answer 25

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