Neuromuscular system Flashcards
What is a motor unit
Motor neurone and the muscle fibres it innervates
Only one type of muscle fibre is found in each motor unit
How many fibres small muscles have in its unit
Few fibres for fine motor control
How many fibres large muscles have in its unit
Hundreds of fibres for gross muscle control
What is the all or none law
Once the motor neuron stimulates muscle fibres, either all of them contract or none of them contract
There must be great enough action potential for this to occur
How is the strength of contraction altered
More motor units are recruited
More impulses are sent
Wave summation
Fast and frequent impulses cause strong contractions
Tetanus is when maximum muscle tension is maintained
No time to relax
Spatial Summation
Impulses sent down different motor units at different times
Notation - Sharing of workload, sustained contraction and reduction of fatigue
Rotate innervations
