neuromuscular system Flashcards
what are motor neurons
specialised cells which transmit nerve impulses rapidly to a group of muscle fibres
what is a motor unit
contains motor neuron and its muscle fibres
what components make up a motor neuron
- cell body - found in the brain/ spinal cord
- axon
- motor end plate
what does the autonomic nervous system do
regulates function of our internal organs such as the heart
also controls some of our skeletal muscles within the body
it works involuntarily
what is the sympathetic nervous system
prepares body for fight or flight
what is the parasympathetic nervous system
relax and slows down high energy functions
rest and relx
wha tare the three types of muscle fibres
- type 1 = slow oxidative
- type 2 = fast oxidative glycolytic
- type 2x = fats glycolytic
mix of muscle fibres is genetically determined
what are slow twitch muscle fibres - type 1
- aerobic activity
- store oxygen in myoglobin
- small amount of force
- resistant to fatgue
e.g. an elite endurance athlete will have a greater proportion of slow twicth fibres in their gastrocnemius ( 70 % )
what are fast twitch muscle fibres - type 2
- anearobic
- large amount of force
- fatgue quickly
e.g. power events
what are fats twitch muscle fibres - type 2 a
- anaerbic
- large amount of force quickly
- more resistant to fatigue than type 2x
- generate less force than 2x
E.g. speed endurance activities such as 800m
what are fast twitch muscle fibres type 2x
- highest anaerobic capacity
- generate greatest amount of force
- lowest resistance to fatigue
E.g. very high intensity such as 100m sprint
structural characteristics of type 1 ( SO) muscle fibres
- neuron size = small
- fibres per neuron = few
- mitochondria desnity = high
- capillary density = high
- myoglobin content= high
- pc stores = low
- glycogen stores = high
- triglyceride stores = high
structural characteristics of type 2a (FOG ) muscle fibres
- neuron size = large
- fibres per neuron = many
- mitochondria desnity = moderate
- capillary density = high
- myoglobin content= moderate
- pc stores = high
- glycogen stores = high
- triglyceride stores = moderate
structural characteristics of type 2 x (FG) muscle fibres
- neuron size = large
- fibres per neuron = many
- mitochondria desnity = low
- capillary density = low
- myoglobin content= low
- pc stores = high
- glycogen stores = low
- triglyceride stores = low
functional characteristics of type 1 (SO) muscle fibres
- speed of contraction = slow
- force of contraction = low
- resistance to fatigue = high
- aerobic capacity = high
- anaerobic capacity = low
functional characteristics of type 2a (FOG) muscle fibres
- speed of contraction = fast
- force of contraction = high
- resistance to fatigue = moderate
- aerobic capacity = moderate
- anaerobic capacity = moderate
functional characteristics of type 2x (FG) muscle fibre types
- speed of contraction = fastest
- force of contraction = highest
- resistance to fatigue = lowest
- aerobic capacity = low
- anaerobic capacity = high
how many types of muscle fibre can be found in one particular motor unit
one
- the motor neuron transmits the nerve impulse to the muscle fibre
each motor neurone has branches that end in the neuromuscular junction on the muscl fibre
what is a neuromuscular junction
the point where the axons motor end plates meet the muscle fibre
what is an action potential
cannot cross trhe synaptic cleft without a neurotrasnmitter called acetylcholine
what is a neurotransmitter
secreted into the synaptic cleft to help the nerve impulse cross the gap
what is a muscle action potential
if enough of the neurtransmitter is secreted and the electrical charge is above threshold a muscle action potential is created. The action potential creates a wave of contractiom down the muscle fibre
what is the all or non law
1) nerve impulse initiated in the motor neuron cell body
2) nerve impulse conducted down the axon of the motor neuron by a nerve action potential to the synaptic cleft
3) neurotransmitter called acytl choline is secreted into the synptic cleft to conduct the nerve impulses across the gap
4) if the electrical charge is above threshold, the muscle fibre will contract
5) this happens in an all or none fashion
what is wave summation
where there is a repeated nerve impulse with no time to relax so a smooth muscle sustained contraction occurs, rather than twithes
