skeletal muscle contraction Flashcards
motor unit definition
a motor neuron plus all the muscle fibres it innervates
motor unit function
to carry impulses from the central nervous system to the muscle fibres to initiate muscle contraction
STEP 1 muscle contraction response
stimulus from sporting action to the CNS via the sensory neuron
STEP 2 muscle contractions response
CNS responds by sending a message to the motor neuron
action potential starts charge
STEP 3 muscle contraction response
the greater the strength of the message the more motor units recruited
STEP 4 muscle contraction response
muscle fibres will be recruited if the threshold of the action potential is reached
STEP 5 muscle contraction response
Movement created by motor unit - known as ‘ All or None Law’
Action potential
the electrical activity carried down the axon
resting potential
the neuron at rest there is a lower charge inside to outside
Acetyl choline
the neurotransmitter realise at neuromuscular junction that travels across synapse
‘All or None Law’
once action potential threshold is reached all muscle fibres in the motor unit are activated
neuromuscular junction
where the motor neuron communicates with a muscle fibre across the synapse
effect of number of motor units recruited
the greater the strength of stimulus from CNS
- the greater the number of motor units recruited
- the greater force of contraction in the muscle
Type 1 muscle fibres
slow oxidative SO
- endurance fibres
- low force of contraction over long period of time
Type 2a
fast oxidative glycolytic FOG
- speed endurance fibres
