Neural Control of Muscles Flashcards
(15 cards)
What two structures make up a motor unit?
- A motor neuron
- Muscle fibre
What is the ‘all or nothing’ principle?
That muscle fibres will not be stimulated until the nerve impulse reaches a certain threshold. Once it reaches that level, the muscle fibres will contract all at once, and maximally.
What is the size principle?
That smaller contractions require smaller motor units as they require less force production. Larger contractions require small then large motor units to generate more power.
How can the size of muscular contractions be varied?
- By varying the number of nerve impulses released
- By varying the frequency they are released
What is a concentric contraction?
When muscles shorten and the joint angle decreases.
What is a eccentric contraction?
When muscles lengthen and joint angle increases.
What is an isometric contraction?
When muscles and joint stay the same as it resists gravity - tires easily.
What is the muscle origin?
The point of its attachment to a stationary bone
What is the muscle insertion?
More moveable end of the muscle.
What is the agonist?
The prime mover, causes the major action
What is the antagonist?
The muscle which must relax and lengthen for the major action to take place.
What is the stabiliser?
The muscles which ensure that the joint remains stable while the action occurs
What is reciprocal inhibition?
The process of the agonist and the antagonist working together to create the action.
3 parts of levers in the body?
- Axis: the joint
- Force: the muscles which contract to generate the force to move the lever
- Resistance: the bone and whatever else is being moved
What is mechanical advantage?
The degree to which a lever amplifies force or speed.
