Lecture 3 - Week 2B Flashcards
why does upper limit of recuitment/recuritment range vary between muscles?
because it depends on the function of msucle for exmaple adductorepolicis in the hand with have a lower MVC then soleus because only needs to do things like write wheras seoleus needs larger force for jumping
Eric is exercising at Dwight Schrute’s Gym for Muscles and progressively increases the weight that he is lifting. What neural strategies, in context of a motor unit, will allow him to increase his force? (2 points)
increase recuitment of motor units -recruit mroe motor units
rate coding - increaing rate of rirng of motor units - the faster theyb fire teh mroe force fenerated in msucle fibers
how would neural strategies change if one was performing fast olympic contraction versus slow contractions with same resistane
rate coding would change - rate coding would have to increase so that MU are fired at a faster frequency in order to produce more force in a short amoutn time to produce explosive power
in contrast - rate coding would be slower for slower contraction as it relies more on sustained force and cam have slwoer firing
what are the 2 ways that neruons can communicate?
Divergence - single nueron synapse on multple neurons converge on fewer
what is divergence (inneuron communciation_
one neuron multiple neruons
what is convegence
multiple neruons convege on fewer
what are intrafusal peripheral structures? extrafusual?
msucel spindles
skeletal msucle
afferent is ____ the brain
efferent is ____ the brain
towars = affernet
efferent = exit brain
are msucle spindle intra or extrafusal?
intra
each afferent projects centrally to the ___ and ___ with cell body in ___
spinal cord (reflexes) and brain cell body in dorsal root ganglion
where is the cell body of afferents found?
dorsal route ganglion
what are afferents labeled based on?
cross esctional diameter , I being the largest and IV being the smalleste
affernts are also known as ___
sensory
larger diameter such as in afferents = ____ conduction
faster
what two afferentswat afferent nerces are involved with muscle spindles
group Ia and II
what do group Ia afferents transmit.
msucle spinldes - info on length and velocity
what are afferents?
nerve fibers taht carry info from bodys sense organs to brain/spinfal chord (also known as sensory neurons)
what do group II afferents detect?
static length of muscle spindles
what are teh 5 types of afferents we learn
Ia, II, Ib, III, IV
what affernt has the fastest conduction velocity and why?
group Ia (muscle spindles) as they havet the largest diameter
what afferent has the slowest conduciton velocity? why?
group IV - smalled CS diameter
msucle spindles lie ____ to skeletal msucles
parallel
the number of spindles in a muscle is the same in all muscles
false/ the density changes depednign on th emuscle - hand muscles have hgiher desnity while proximal have fewew (biceps)
what are. msucle spindles also known as
intrafusal muscle fibres
what are the two types of recepetors in a musce spindle
Bag and chain
what does bag 1 detec?
dynamic
what 2 receptor detect static changes?
bag 2 and chain
what do type Ia fibres detect and which receptors do they innervate
type I a fibres detect length and velocity and inn Bag 1. bag 2 and chain recpetors
what do type II fibres detect and which receptors do they innervate
tyep II fibres detect just length and inn bag 2 and chain
primary afferents are also known as ___ andtheir function is. -___ send infro from ____ receptors
Ia -
velcoity and length of stretch
send info from all spindle receptors (dynamic + static)
secondary afferents also known as ___ function is ____ and send info from ____ recptors
type II, lengh of stertch, info form static receptors
how do we record muscle spindles What does this detect
microneurography - dtects single unti action potentiasls
whenyou stretch a muscl waht happens simply?
get Ia and II responses to stretch taht code for lenght and rate ogf change of length (velocity)
what afferents are incolved
___ are inclved in teh monosynaptic refelex
primaries (Ia) - sensitive to taps and vibration and stop firing on release
what is the only receptor to have its own motor sytem and what is taht motr ststme called?
muscle spindles - gamma system - consits of dynamic and static gamma MN’s
waht is differnce betwen skeltomotor and fusimotor?
skeltomotor motor netons (alpha) directly contraol scontraction o fskeltetal msucles while fusi motor inn muscle spindles
In terms of efferents alpha motor neuron sends info to _____ while gamma motor neurons sends info to ____
alpha mtoor neurons to skeletal muscle fibers
gamma motor neurons to muscle spindles
dynamic gamma send info too____
whiels atic gamma send info to -__
bag 1
bag 2 + chain
why do msucle spindles have tehir won system and why is this sytme so importnat?
turninng on the gamma system rpevents the spindle from becoming unlaoded during shortening contaction and keeps it sensitive to strecth
Gamm dynamic make spindle more velocity sensitive whiel gamma astatic makes psindle morelength sensitive
why do we need to coactivate alpha and gamma systems/
the msucle spidnle system on its own would cause msucle spindles to become unloaded and stop firing when the muscle shortens - bad feedback
bt coactivating the msucle spinde maintains sensitivity during a shorteinign contraction
