Muscle fibre recruitment Flashcards
1
Q
The Neuromuscular system
A
- The movement of muscles is controlled by the brain.
- The brain is connected to the muscles via nerves.
- In order for a muscle to contract a nerve impulse is sent along a nerve to the muscle.
- If the signal is strong enough the muscle will contract.
2
Q
What are muscles made of?
A
- The muscle is made of thousands of muscle fibres which are split into groups.
- These groups are called motor units and they are controlled by a motor neuron.
3
Q
Define a motor unit
A
- A motor neuron and its muscle fibres.
4
Q
Motor units (info)
A
Motor units are either fast or slow twitch units.
- Muscles are made up of both.
They also vary in size (15-2000 muscle fibres).
5
Q
What is the all or none law?
A
- In order for the motor unit to contract it must be stimulated by a nerve impulse.
- If the nerve impulse is strong enough a threshold will be crossed which causes the motor unit to fully contract (ALL).
- If the nerve impulse is not strong enough a threshold will not be crossed which will cause the motor unit to not contract (NONE).
6
Q
What is spatial summation?
A
Spatial summation is how the brain varies the strength of a muscular contraction.
- The force of contraction depends on the number, type and size of the motor units being stimulated.
7
Q
What is the strength of a contraction varied by?
A
- Recruiting larger motor units- more force/ strength.
- Recruiting more motor units- more force/ strength.
- Recruiting fast twitch motor units- more force/ strength.
- Tetanic contraction
8
Q
What is wave summation?
A
- This is where repeated nerve impulses are sent to the muscle giving it no time to relax. As a result a smooth, sustained contraction occurs rather than twitches.
9
Q
What is a tetanic contraction?
A
- This is where repeated impulses are rapidly sent to the muscle giving it no time to relax. As a result a smooth, sustained contraction occurs until maximal contraction.
