1.3 The Neuromuscular System Flashcards
what is the autonomic nervous system
involuntary and subconscious bodily responses
what two parts make up the autonomic nervous system
- parasympathetic
- sympathetic
what is the role of the sympathetic nervous system
it prepares the body for exercise and is often refereed to as ‘fight’ or ‘flight’
what is the role off the parasympathetic nervous system
relaxes the body and slows down many high energy functions
what are the three types of muscle fibre
- slow oxidative (type 1) often called slow twitch
- fast oxidative glycolytic (type IIA)
- fast glycolytic (type IIB)
what are the functional and structural characteristics of slow twitch fibres (type 1)
functional: - slow contraction speed - low force produced - fatigability low structural: - high capillary density - low glycolytic capacity - high mitochondrial density - high myoglobin
what are the functional and structural characteristics of fast twitch type IIA
functional: - fast contraction speed - high force produced - medium fatigability structural: - medium mitochondrial density - high glycolytic capacity - medium capillary density - medium myoglobin
what are the functional and structural characteristics of fast twitch type IIB fibres
functional: - fast contraction speed - high force produced - high fatigability structural: - low capillary density - low mitochondrial density - low myoglobin - very high glycolytic capacity
give examples of what each of the muscles fibre would be best used for
type 1 slow twitch- aerobic activity like jogging or walking
type IIA - anaerobic activity but more resistant to fatigue than type IIB so 1500m
type IIB- anaerobic and explosive activity like 100m sprint
define a motor unit
a motor neurone and its muscle fibres
what is a motor neurone
nerve cells that transmit the brains signals as electrical impulses to the muscles
what is the all or none law
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 ALL of them to contract. if not none of them contract.
READ :
motor units contain the same type of muscles fibre so they are either slow twitch or fast twitch motor units. the brain will recruit slow twitch motor units for low intensity activities and fast twitch motor units for high intensity exercise like weight lifting.
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name 2 ways the strength of a contraction can be changed
- spatial summation
- wave summation
define wave summation
where there is a repeated nerve impulse with no time to relax. repeated activation of a motor neurone stimulating a given motor units muscle fibres resulting in a continuous wave of stronger contractions known as wave summation.
