Muscular system Flashcards
what does wave summation do?
changes the frequency of nerve impulses arriving at the muscle fibres. Increased frequency = a greater force of contraction.
- also allows a smooth sustained contraction rather than twitches (a tetanic contraction)
what is a tetanic contraction?
a sustained muscle contraction caused by a series of fast repeating stimuli.
what does spatial summation do?
controls both the strength and duration of a muscle contraction
how does spatial summation work to control the strength of a contraction?
the size and number of motor units recruited will determine the size.
- many large motor units (fast twitch fibres) simultaneously = maximal force
- low numbers of small motor units = low force
how does spatial summation work to control the duration of a contraction?
allowing some motor units to rest whilst others recover meaning they can be rotated (whilst still applying the necessary force). Therefore the motor units can swap and the ones just used in the contraction get time to rest.
