Neuromuscular System Flashcards
Motor unit
Consists of one motor neuron and all the muscle fibres it stimulates.
Made up motor nueron, axon terminal and muscle fibres
Spatial summation
The change in contraction strength due to its change in number/size of motor units
What is the all or none rule
Where a sequence of impulses has to have sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract. If there is not enough, none contract.
How do our muscles exert different amounts of force for different actions
Our brain recruits different types of muscle fibres eg. Fast or slow twitch. If a greater force is required, more motor neurons will be activated
Wave summation
When there is a repeated nerve impulse with no time to relax, a smooth and sustained contraction occurs rather than twitches creating more tension in the muscles through repeated impulses.
Tetanic contraction (tetanus)
Continuous muscle contraction caused by many quick impulses. No rest periods and it is at maximal effort for one large contraction
PNF stands for…
Proprioceptive neuromuscular facilitation
PNF stretching
Advanced stretching technique
One of the most effective forms of flexibility training
Muscle spindles
These detect how far and how fast a muscle is stretched so that the central nervous system can send impulses back to the muscle telling it to contract hence producing the stretch reflex to prevent overstretching
Golgi tendon organs
These detect when there is tension in a muscle and send inhibitory signals to the brain allowing the antagonist muscle to relax. This is known as autogenic inhibition
Isometric contraction
When there is tension in a muscle but no visible movement
Autogenic inhibition
When there is a sudden relaxation of the muscle in response to high tension.
