Skeletal Muscle Physiology II Flashcards
every somatic motor neuron will only innervate _ fibre type
ONE
word used to describe activation of certain muscles fibres
recruit
can a motor unit activate multiple different types of fibres?
NO
motor unit summation
increase of motor use (in numbers) until response reaches maximal stimulus
which strength of fibres are recruited first?
weaker
and then stronger
motor unit
a motor neuron and all of its associated muscle fibres
asynchronous recruitment
alternate between motor units between contractions to allow them to relax
where would you find large vs small motor units
small: smaller muscles for fine movement
large: larger muscles for powerful movements
what creates the difference in max muscle tension between people?
number of myofibrils in each muscle fibre
- number of muscle fibres doesn’t change from birth, but pr- inside can change
2 main types of contractions
- ISOMETRIC: length of muscle doesn’t change tension increases
- ISOTONIC CONTRACTIONS: tension constant, length of muscle changes
- CONCENTRIC: muscle shortens when tension >resistance
- ECCENTRIC: muscle lengthened when resistance>tension
3 fibre types
- TYPE I MUSCLE FIBRES: slow twitch, high oxidative
- Slow Oxidative (SO)
- slow ATP breakdown
- smaller, less myofibrils
- more mitochondria
- better blood supply
- fatigue resistant - TYPE IIa MUSCLE FIBRES: fast twitch, low oxidative
- Fast oxidative-glycolytic (FOG)
- fast ATP breakdown
- larger than type 1
- less mitochondria
- less blood supply
- less aerobic - TYPE IIx MUSCLE FIBRES
- Fast Glycolytic
- largest, strongest
- fewest mitochondria
- least blood supply
- lowest aerobic capacity
- fatigueable
impact of endurance or strength training on muscle fibre changes
strength: type IIa to type IIx
endurance: type IIx to type IIa
what types of muscle fibres can change?
type IIx
type IIa
