Muscle fibre recruitment Flashcards
What is the neuromuscular system?
The movement of muscles, is controlled by the brain - via nerves.
When will a muscle contract?
When the signal from the brain, through a nerve impulse, is strong enough.
What are motor units
Groups that have a motor neurone and muscle fibres. They can vary from 15-2000 muscle fibres
Where are slow twitch motor units found, and what are they used for?
- In large muscles like the quadricep; to produce more powerful movements.
Where are fast twitch motor units found, and what are they used for?
In small muscles, like the eyelid; to produce less powerful movements (blink)
What is the all or none law?
If a nerve impulse is strong enough, a threshold will be crossed and the muscle will contract. If not then the threshold will not be crossed and the muscle will not contract.
What is spatial summation?
How the brain varies the strengtj of a muscular contraction.
What 4 things varies the strength of contraction?
- Recruiting larger motor units
- Recruiting more motor units
- Recruiting fast/slow motor units
- Tetanic contraction
What dictates what motor units are recruited?
The type of activity
E.g. jogging = slow twitch, smaller, fewer, wave summation.
E.g. sprinting = fast twitch, larger, more, tetanic contraction
What is wave summation?
Where repeated nerve impulses are sent to the muscle giving it no time to relax. As a result a smooth, sustained contraction occurs.
What is a tetanic contraction?
Where repated nerve impulses are rapidly sent to the muscle giving it to time to relax. As a result a smooth, sustained contraction occurs until maximal contraction
