3.1.1.4 Neuromuscular system Flashcards
autonomic nervous system
- regulates function of internal organs e.g. heart
- involuntary
- sympathetic nervous system = prepare for exercise (fight or flight)
- parasympathetic nervous system = relax body & slows down many high energy functions (rest and relax)
neuromuscular system
-controls muscles during exercise
Brain -> Nerves -> Muscles
-nerves and muscles work together to = movement
-sympathetic and parasympathetic nervous system = help prepare neuromuscular system for exercise
-transmits info from brain to parts of body
muscle fibre types
3 types of motor unit
2 = fast twitch fibres
1= slow twitch fibres
-muscles = mixture of all 3 types determined by genetics
fast twitch glycolytic
FG or type 2x
fast (50) speed of contraction
highest force of contraction
large fibre & motor neurone size
high and very high PC and glycogen stores
anaerobic shot put
fast twitch oxidative glycolytic
FOG or type 2a
fast (50) speed of contraction
high force of contraction
large fibre size
large motor neurone size
activity = 1500m
slow twitch
ST or 1
-slow (110) speed of contraction
-small fibre size
high myoglobin content
small motor neurone size
aerobic activity (marathon)
motor neurone size
the larger the diameter of motor neurone = faster speed of impulses
postural muscles
- type 1 fibres - maintain body posture
- increase size muscle fibres- training = hypertrophy = greater strength of the muscle
examples of events and muscle fibre types
100m: 30% type 1, 30% type 2a, 40% type 2 x
marathon: 70% type 1, 15% type 2a, 15% type 2x
footballer: 45% type 1, 40% type 2a, 15% type 2x
motor unit
motor nerve and the muscle fibres it stimulates
- 1 neurone controls a number of muscle fibres
- single neurone = control fibres of same type not a mixture of fibre types
-always 1 nerve but number of fibres can vary
motor neurone/nerve structure
-conducts nerve impulses to muscle fibres
- thicker nerve = faster impulse travels (type 2x = thickest)
- cell body and cytoplasm
- dendrites (collect signals)
- axons of nerve fibres (passes signals)
- myelin sheath
- node of Ranvier (gaps in the myelin sheath)
- axon terminal
- muscle fibres & synaptic end bulb
- neuro-musclar junction (where muscle joins with nerve)
all or none law
-when a neurone is stimulated all fibres connected to that neurone are activated at once
threshold definition
minimum amount of stimulation required to start a contraction
ways to control force of contraction/variation in strength of muscle contraction (how can muscle vary force produced)
- recruiting: slow twitch motor units for low intensity activity
- wave summation: increasing frequency of nerve stimulus
- spatial summation: varying number of motor units recruited
fibre type and exercise
-recruitment (based on intensity of exercise)
low = ST motor units recruited
higher = FOG, FT, 2a
greatest intensity= FG, FT, 2x (powerful fast contractions)
wave summation
REPEATED NERVE IMPULSE = SMOOTH SUSTAINED CONTRACTION (NO REST TIME)
- nerve impulse reach muscle cell = calcium
- calcium =present (sarcoplasm) =muscle contract
- same fibre group fired repeatedly will build the force exerted by wave summation
tetanic contraction
- no time for relaxation between motor unit firing
- calcium builds up in muscle cells = causes complete lock up of muscle
- twitch
- summation
- incomplete tetanus
- complete tetanus
spatital summation
STRENGTH OF CONTRACTION CHANGES BY ALTERING NO/SIZE OF MOTOR UNITS
- different fibre groups are fired in succession to control a movement
- total force across the space of a muscle is the sum of the effect of different fibre groups
3x motor units broken down = total force across muscle
Action potential
when a neuron has an electrochemical impulse passing down its axon.
Types of contraction
Twitch
Wave summation
Spatial summation
Tetanus
Tetanus
- sustained muscle contraction
- motor neurone receives action potentials at a very rapid rate
Synapse
When one neurone joins another neurone
recruitment
based on intensity of exercise
low: ST motor unit recruited first
higher: FOG/FT/2a motor units recruited
greatest: FG/FT/2x motor units recruited
to produce powerful fast muscle contractions
tetanic contraction
no time for relaxation between motor unit firing
calcium build up in muscle cell
cause complete lock up of muscle
stretch reflex
reflex contraction of muscle in response to a sudden rapid stretch
protecting muscle against possible tears/strains
proprioceptors
help control muscle contractions
- located in skeletal muscle, joint capsules & tendons and provide sensory info on:
1. body movement
2. orientation in space
3. muscle stretch
reciprocal inhibition
process which occurs in an antagonistic pair of muscles
inhibit stretch reflex
-when agonist muscle contracts = sends out inhibitory nerve impulses to its opposing muscle (antagonist) causing it to relax as a result of reflex action
e.g. bicep contracting switch off tricep
muscle spindle
very sensitive proprioceptor found in skeletal muscle
- prevent injury
- afferent nerve stimulated when length of relaxed muscle stretched and exceeds certain limit
- triggers off response via efferent nerve = initiates reflex muscle action = shortens a muscle/muscle group
afferent nerve
sensory neurone
efferent nerve
motor neurone
tendon
muscle to bone
ligament
bone to bone
Golgi tendon organs
- located at junction between muscle and tendon
- too much tension in muscle = muscle relax
- excessive muscle contraction = Golgi tendon reflex or Autogenic inhibition
- protect from tearing/pulling away from tendinous points of attachment to bones
- activated after hold (isometric contraction) = further relaxation of muscle (muscle spindle reflex switched off)
PNF stretching
Proprioceptive neuromuscular facilitation
-flexibility
-static /dynamic/ballistic not as effective as PNF
-use alienation contraction and relaxation movement
-passive or active
CRAC technique
-isometric contractions (hold/no movement)
CRAC technique
contract
relax
antagonist
contract
Process of PNF
- tension on tendon activate sensory neurone
- sensory neurone stimulates interneurone
- interneurone inhibits motor neurone
- tension on tendon reduced
- passive stretch
- muscle spindles detect= limit = stretch reflex
- isometric contraction (push away from partner) = tension in muscle = GTO reflex activated = autogenic inhibition detect tension = turns off stretch reflex
- stop isometrically contracting stretch reflex temporarily switched off = increase range of movement
interneurone
- connect spinal motor and sensory neurone
- transfer signals between sensory & motor neurons,
motor end plate or neuromuscular junction
-connection between a motor neurone and its fibres
4 functional characteristics list
- speed of contraction
- force of contraction
- fatiguability
- anaerobic/aerobic capacity
6 structural characteristics list
- fibre size
- mitochondrial density
- capillary density
- myoglobin content
- myosin/ATPase glycolytic enzyme activity
- motor neurone size
motor neurone definition
nerve cells that transmit brains instructions as electrical impulses to muscles
