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EP 4703 Unit 2 > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

what are the simplest muscle reflexes acting in the body

A

monosynaptic

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2
Q

why is the functional importance of monosynaptic reflexes questionable

A

they induce brisk, brief contractions that are poorly controlled voluntarily

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3
Q

monosynaptic reflexes are unlikely to be part of mechanism for ____________

A

voluntary control of movement

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4
Q

what is similar about the H and T reflexes

A

same monosynaptic pathway
take about the same amount of time
both utilize muscle spindle afferents

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5
Q

what is different about the H and T reflexes

A

H= electrical stimulation
T= mechanical stimulation
H has motor response and reflex
T only has reflex

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6
Q

how many central synapses are there in an oligosynaptic reflex

A

2-3

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7
Q

how many central synapses are there in a polysynaptic reflex

A

many, usually 4 or more

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8
Q

what is an example of an oligosynaptic reflex

A

reciprocal inhibition

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9
Q

what are 3 primary differences between a polysynaptic reflex and a monosynaptic reflex

A
  • mono effects one muscle group, poly effects many
  • amount of central synapses
  • poly is more smooth, controlled
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10
Q

what are good examples of oligosynaptic reflexes

A

Ia and Ib afferents

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11
Q

Ia interneurons receive excitatory inputs from Ia afferents and make inhibitory synapses on alpha motoneurons innervating the antagonist muscle

A

reciprocal inhibition

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12
Q

what type of reflex effect do Ia interneurons have during reciprocal inhibition

A

oligosynaptic inhibitory

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13
Q

when GTOs send their axons (Ib afferents) to Ib interneurons what action is exerted on the agonist alpha motoneurons

A

inhibitory

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14
Q

when GTOs send their axons (Ib afferents) to Ib interneurons what action is exerted on the antagonist alpha motoneurons

A

disinhibit

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15
Q

commonly, __________ reflexes receive contributions from receptors of different modalities and their central pathways are _________

A

polysynaptic

unknown

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16
Q

the flexor reflex is induced by a group of afferents called _________

A

flexor reflex afferents

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17
Q

what three things do flexor reflex afferents include

A

secondary endings of muscle spindles
free nerve endings
cutaneous receptors

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18
Q

the flexor reflex leads to an activation of what

A

flexor muscles within the same limb

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19
Q

what is an example of a flexor reflex

A

tibialis anterior response to an electrical stimulation of n. suralis

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20
Q

all monosynaptic reflexes are _______ reflexes

A

phasic

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21
Q

______ reflexes occur all of the time

A

tonic

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22
Q

______ reflexes emerge in response to a change in the level of a stimulus specific to the receptor

23
Q

type of reflex that is typically a burst or brief depression of muscle activity that leads to a twitchy or series of twitchy movements

A

phasic reflexes

24
Q

_______ reflexes emerge in response to the level of a stimulus

25
type of reflex that typically leads to sustained muscle contractions and relatively smooth moevements
tonic reflexes
26
muscle spindles can lead to what type of reflex
phasic and tonic
27
if a muscle stays in its stretched state the ________ reflexes disappear rapidly
phasic
28
if the muscle was active before the stretch _______ changes may be observed after the stretch is completed and the muscle is at a ____ steady state
tonic | new
29
a muscle is slowly stretched by what type of force
external
30
external force examples
weight | gravity
31
during the tonic stretch reflex, first it _______ the stretching only due to its passive elasticity
resists
32
during TSR at a certain threshold recruitment of alpha motoneurons begins, leading to ______ force development
active
33
the whole TSR curve is called a ________
tonic stretch reflex characteristic
34
what activities induce the TSR
walking | jumping
35
7 steps to the tonic stretch reflex
1. muscle slowly stretched by external force 2. resist stretching by passive elastic properties 3. @ certain length, few alpha MNs recruited 4. active force development opposes stretch 5. length @ which recruitment begins = threshold of the TSR 6. muscle lengthens, more MNs recruited, muscle force increases 7. TSR characteristic reveals relationship btween muscle length and force
36
the TSR is a major mechanism that defines what
the viscoelastic properties of muscles, joints, and limbs
37
what can the TSRs threshold be viewed as
a control variable manipulated by the brain
38
what is NOT exclusively manipulated by the brain
muscle activation levels forces changes in joint angles
39
Muscle activation, forces, and changes in joint angles emerge with equal participation from __________
central commands (brain) and external loads (reflexes)
40
high frequency muscle vibration leads to a slow reflexive increase in muscle force
tonic vibration reflex
41
TVR _________ afferent information
suppresses
42
TVR is accompanied by a suppression of _________ reflexes in the same muscle
monosynaptic
43
the suppression of the H reflex is of a _______ origin
presynaptic
44
muscle vibration can induce __________ of different muscles of the same limb
reflexive contractions
45
_________ receive mixed information from afferents originating from different receptors
Ia and Ib interneurons
46
a stimulation of the flexor reflex afferents in a limb induces what two things
- a reflex response in flexor muscles of the limb | - a crossed extensor reflex in extensor muscles of the contralateral limb
47
the _______ is unknown in polysynaptic reflexes because there are so many which makes it hard to trace
reflex loop
48
polysynaptic reflexes involve ______ muscles
distant
49
reflexes that have longer latency, slow, steady state character
polysynaptic
50
four examples of polysynaptic reflexes
- flexor reflex - crossed extensor reflex - tonic stretch reflex - tonic vibration reflex
51
what happens at the threshold of the tonic stretch reflex
- recruitment of alpha motoneurons in muscle that is lengthening to produce force to counter the movement - as muscle lengthens, muscle spindles are activated
52
what happens as the muscle continues to lengthen
more motoneurons recruited and muscle force is increased
53
a person steps on a sharp object. which two reflexes would be excited and how would they work together
- flexor reflex on affected leg to pull it up | - cross extensor on contralateral leg to support
54
what happens to the H and T reflex when vibration is applied
they are suppressed

EP 4703 Unit 2 (3 decks)

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