1.3 - The neuromuscular system Flashcards
define neuromuscular system
where the nervous system and the muscles work together to allow movement
effect of the sympathetic nervous system on the body:
prepares the body for exercise
referred to as the ‘fight or flight’ response
effect of the parasympathetic nervous system on the body:
relaxes the body
slows the body down
‘rest and relax’
what are slow oxidative fibres (type 1)
slower contraction speed
better adapted for lower intensity exercise (e.g long distance running)
produce most of their energy aerobically
what are fast oxidative glycolytic fibres (type IIa) ?
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.
what are fast glycolytic fibres (type IIb) ?
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
what are characteristics of the twitch fibres?
mention: contraction speed, motor neurone size, force produced, mitochondrial density, myoglobin content, aerobic capacity and anaerobic capacity.
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
define hypertrophy
where the muscle has become bigger and stronger
define a motor unit
a motor neurone and its muscle fibres
define a motor neurone
nerve cells which transmit the brain’s instructions as electrical impulses to the muscles
define a neuromuscular junction
where the motor neurone and the muscle fibre meet
how do motor units create movement?
the motor neurone transmits nerve impulses to the muscle fibre, creating movement
what is the all or none law?
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)
what is a slow twitch motor unit?
used for low intensity activity
e.g jogging, long distance swimming
what is a fast twitch motor unit?
when a greater force of contraction is needed
e.g sprinting, power lifting
how do you increase the strength of a contraction?
wave summation
spatial summation
what is wave summation?
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)
what is spacial summation?
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
what does PNF stand for?
proprioceptive neuromuscular facilitation
what is PNF?
an advanced stretching technique
most effective form of flexibility training for increasing range of motion
what are muscle spindles?
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 )
what are golgi tendons?
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)
Give an example of PNF in practice.
- 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)
define isometric contraction.
where there is tension in a muscle but no visible movement
