neuromuscular system Flashcards
Define hypertrophy
When a muscle becomes bigger and stronger
Define motor unit
A motor neurone and its muscle fibres
Define motor neurone
Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles
Define neuromuscular junction
Where the motor neurone and the muscle fibre meet
What is the all or none law?
Where a series of impulses has to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract. If not, none of them contract.
Define wave summation
Where there is a repeated nerve impulse without time to relax so a smooth, sustained contraction occurs, rather than twitches.
Define a tetanic contraction
A sustained muscle contraction caused by a series of fast repeating stimuli.
Define spatial summation
When the strength of a contraction changes by altering the number and size of the muscle’s motor units.
What are muscle spindles and how do they work?
Sensitive proprioceptors, laying between the skeletal muscle fibres that send excitatory signals to the CNS about how fast + how far a muscle is stretching. The CNS then sends an impulse back to the muscle, telling it to contract, triggering a stretch reflex (muscle contraction to prevent overstretching.)
What are golgi tendon organs?
Located between the muscle and the tendon, when the muscle contracts isometrically, they sense the increase in muscle tension. They send inhibitory signals to the brain, allowing the antagonist muscle to contracts and lengthen.
What is an isometric contraction?
Where there is tension in a muscle but no visible movement
What is autogenic inhibition?
Where there is a sudden relaxation of the muscle in response to high tension. The receptors involved in the process are golgi tendon organs.
What are the different components within a muscle?
Muscle - Fascicle(muscle fibre bundle) - muscle fibre cell - muscle fibril - microfilaments
What are the features of a slow oxidative muscle fibre (type 1?)
- small
- darker red
- lots of mitochondria
- low twitch speed + force
- high fatigue resistance
What sports would type 1 muscle fibres be most useful for?
- jogging
- walking
- aerobics
