Lecture 3 - Week 2B

Question 1

why does upper limit of recuitment/recuritment range vary between muscles?

Answer 1

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

Question 2

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)

Answer 2

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

Question 3

how would neural strategies change if one was performing fast olympic contraction versus slow contractions with same resistane

Answer 3

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

Question 4

what are the 2 ways that neruons can communicate?

Answer 4

Divergence - single nueron synapse on multple neurons converge on fewer

Question 5

what is divergence (inneuron communciation_

Answer 5

one neuron multiple neruons

Question 6

what is convegence

Answer 6

multiple neruons convege on fewer

Question 7

what are intrafusal peripheral structures? extrafusual?

Answer 7

msucel spindles
skeletal msucle

Question 8

afferent is ____ the brain
efferent is ____ the brain

Answer 8

towars = affernet
efferent = exit brain

Question 9

are msucle spindle intra or extrafusal?

Answer 9

intra

Question 10

each afferent projects centrally to the ___ and ___ with cell body in ___

Answer 10

spinal cord (reflexes) and brain cell body in dorsal root ganglion

Question 11

where is the cell body of afferents found?

Answer 11

dorsal route ganglion

Question 12

what are afferents labeled based on?

Answer 12

cross esctional diameter , I being the largest and IV being the smalleste

Question 13

affernts are also known as ___

Answer 13

sensory

Question 14

larger diameter such as in afferents = ____ conduction

Answer 14

faster

Question 15

what two afferentswat afferent nerces are involved with muscle spindles

Answer 15

group Ia and II

Question 16

what do group Ia afferents transmit.

Answer 16

msucle spinldes - info on length and velocity

Question 17

what are afferents?

Answer 17

nerve fibers taht carry info from bodys sense organs to brain/spinfal chord (also known as sensory neurons)

Question 18

what do group II afferents detect?

Answer 18

static length of muscle spindles

Question 19

what are teh 5 types of afferents we learn

Answer 19

Ia, II, Ib, III, IV

Question 20

what affernt has the fastest conduction velocity and why?

Answer 20

group Ia (muscle spindles) as they havet the largest diameter

Question 21

what afferent has the slowest conduciton velocity? why?

Answer 21

group IV - smalled CS diameter

Question 22

msucle spindles lie ____ to skeletal msucles

Answer 22

parallel

Question 23

the number of spindles in a muscle is the same in all muscles

Answer 23

false/ the density changes depednign on th emuscle - hand muscles have hgiher desnity while proximal have fewew (biceps)

Question 24

what are. msucle spindles also known as

Answer 24

intrafusal muscle fibres

Question 25

what are the two types of recepetors in a musce spindle

Answer 25

Bag and chain

Question 26

what does bag 1 detec?

Answer 26

dynamic

Question 27

what 2 receptor detect static changes?

Answer 27

bag 2 and chain

Question 28

what do type Ia fibres detect and which receptors do they innervate

Answer 28

type I a fibres detect length and velocity and inn Bag 1. bag 2 and chain recpetors

Question 29

what do type II fibres detect and which receptors do they innervate

Answer 29

tyep II fibres detect just length and inn bag 2 and chain

Question 30

primary afferents are also known as ___ andtheir function is. -___ send infro from ____ receptors

Answer 30

Ia - velcoity and length of stretch send info from all spindle receptors (dynamic + static)

Question 31

secondary afferents also known as ___ function is ____ and send info from ____ recptors

Answer 31

type II, lengh of stertch, info form static receptors

Question 32

how do we record muscle spindles What does this detect

Answer 32

microneurography - dtects single unti action potentiasls

Question 33

whenyou stretch a muscl waht happens simply?

Answer 33

get Ia and II responses to stretch taht code for lenght and rate ogf change of length (velocity)

Question 34

what afferents are incolved

Question 35

___ are inclved in teh monosynaptic refelex

Answer 35

primaries (Ia) - sensitive to taps and vibration and stop firing on release

Question 36

what is the only receptor to have its own motor sytem and what is taht motr ststme called?

Answer 36

muscle spindles - gamma system - consits of dynamic and static gamma MN's

Question 37

waht is differnce betwen skeltomotor and fusimotor?

Answer 37

skeltomotor motor netons (alpha) directly contraol scontraction o fskeltetal msucles while fusi motor inn muscle spindles

Question 38

In terms of efferents alpha motor neuron sends info to _____ while gamma motor neurons sends info to ____

Answer 38

alpha mtoor neurons to skeletal muscle fibers gamma motor neurons to muscle spindles

Question 39

dynamic gamma send info too____ whiels atic gamma send info to -__

Answer 39

bag 1 bag 2 + chain

Question 40

why do msucle spindles have tehir won system and why is this sytme so importnat?

Answer 40

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

Question 41

why do we need to coactivate alpha and gamma systems/

Answer 41

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