1.3 The Neuromuscular System Flashcards
(18 cards)
Motor unit
A motor neurone and its muscle fibres
Motor neurones
Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles
Neuromuscular junction
Where the motor neuron and the muscle fibre meet
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 them to contract. If not, none of them contract
3 Types of recruitment of muscle fibres
Wave Summation - RNI
Tetanic contraction - FRS
Spatial Summation - SOC
Wave summation
RNI
Repeated nerve impulse with no time to relax so a smooth, sustained contraction occurs,rather than twitches
Tetanic contraction
FRS
A sustained muscle contraction caused by a series of fast repeating stimuli
Spatial summation
SOC
When the strength of a contraction changes by altering the number and size of muscles motor units
Muscle spindles
These detect how far and fast a muscle is being stretched and produce the stretch reflex
Golgi tendon organs
These are activated when there is tension in a muscle
What is the neuromuscular system?
Where the nervous system and the muscles work together to allow movement. (through nerves)
What are the 3 main types of muscle fibre?
slow oxidative (type 1 - also known as slow twitch)
fast oxidative glycolytic (type 2a)
fast glycolytic (type 2x)
Characteristics of type 1 muscle fibres
High no of mitochondria
High levels of myoglobin
High capillary density
Slow to fatigue
Characteristics of type 2a muscle fibres
Fast oxidative glycolytic / FOG
Fast speed of contraction
High force levels
Quick to fatigue
Characteristics of type 2b muscle fibres
Fast glycolytic / FG
Very fast speeds of contraction
Very high force production
Very quick to fatigue
What is PNF?
Proprioceptive neuromuscular facilitation.
An advanced stretching technique. It is also considered to be one of the most effective forms of flexibility training to increase range of movement.
Autogenic Inhibition
Where there is a sudden relaxation of the muscle is in response to high tension. The receptors involved are the golgi tendon organs
How is PNF used?
Individual performs a passive stretch which is detected by the muscle spindles
Then isometrically contracts for 10 seconds which activates inhibitory signals that override and delay the stretch reflex providing a greater ROM
