LESSON 3 - skeletal muscle & human movement 2 Flashcards
skeletal muscle & human movement 2
what are muscles made up of ?
muscle fascicles
what are fascicles ?
bundles of muscle fibers
what are muscle fibers ?
individual muscle cells
what are muscle fibers made up of ?
myofibrils
what two things do myofibrils contain ?
actin and myosin
what do actin and myosin filaments form?
sarcomere of the muscles
what is the contractile unit of the muscle ?
sarcomere
what type of motor neuron innervates the individual muscle ?
alpha motor neuron
more motor units = ____ motor units
increased
define motor units
a single alpha motor neuron + all the muscle fibers it innervates
↑ operating motor units =
↑ contractile force
around how many muscle fibres does each alpha motor unit innervate ?
20 - 2000 +
if a motor unit innervates 300 muscle fibers how many branches will the axon have ?
300
what is a motor neuron pool ?
the collection of all the alpha motor neurons that innervate one single muscle
define the all-or none principal of motor units …
there is no “slight” vs “heavy” contraction; when a motor neuron fires and an AP is generated, all of the muscle is fibers associated will contact to its fullest potential
force of muscle action carries from slight to max in how many ways ?
one of two ways
what are the two ways that increase force
- increasing NUMBER of recruited motor units
- increasing FREQUENCY of motor unit discharge
what is the formula for power ?
power = force x velocity
what are the three main motor unit characteristics ?
- size (# of muscle fibers innervated)
- physiological properties of their muscle fibers
- biochemical properties of their muscle fibers
when talking about a muscles motor unit size and innervation ratio, which types of muscle will be bigger?
the ones that are being used more often
how do we calculate innervation ratio ?
number of muscle fibers divided by alpha motor axons = innervation rate
how do we calculate contraction time ?
as a function of each motor unit
what are the two types of twitches ?
fast and slow twitch
which type of twitch contraction time develop the greatest twitch force ?
fast twitch
give the acronym for motor unit force x contraction time …
one slow red ox
define the acronym “one slow red ox”
one = type 1 muscle
slow = slow muscle
red = red muscle
ox = oxidative (depends on oxygen)
what are the three muscle fiber type classifications ?
- slow twitch (ST)
- fast twitch a (FTa)
- fast-twitch x (FTx)
describe properties of fast fatiguable (FF : type 2x) :
- fast responding
- slowest contraction time
- highest peak
- not able to maintain the force (over time response falls)
describe properties of fast fatigue-resistance (FR : type 2a) :
- show some fatigue
describe properties of slow (S : type 1) :
- longest contraction times
- does not produce as much force r as quickly
- is highly fatigue resistant
what type of muscle fiber is resistant to fatigue ? (ex. running marathon)
slow oxidative (SO) (ST)
what type of muscle fiber is in the middle ? (ex. playing a sport)
fast oxidative/GLYCOLYTIC (FOG) (FTa)
what type of muscle fiber is highly fatiguable? (sprinters)
fast-glycolytic (FG) (FTx)
FILL IN THE BLANK :
if you want to be a highly aerobic athlete that’s capable of performing high levels of intensity for long periods of time; you must have a high percentage of _____ twitch fibers
slow
what are the two method for altering force production?
- less force production
- more force production
in regards to motor unit recruitment … “less force production =
fewer or smaller motor units”
in regards to motor unit recruitment … “more force production =
more or larger motor units”
what is the size principal ?
order of recruitment relates directly to size of alpha-motor neuron and their “excitability”
define the most excitable (low force) to least excitable (high force) …
type 1, type 2a, type 2x
how can measure the titanic maximal force of a muscle ?
by increasing / stimulating the nerve that innervates that muscle increasing the amplitude of the current
what type of muscle contraction innervates all types of muscles ?
dynamic muscle contraction
dynamic muscle contraction is the coordination of :
- nerve impulses
- calcium release and reuptake
- crossbrudge cycling
- ATP hydrolysis and resynthesis
