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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

A

phasic

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

A

tonic

25
Q

type of reflex that typically leads to sustained muscle contractions and relatively smooth moevements

A

tonic reflexes

26
Q

muscle spindles can lead to what type of reflex

A

phasic and tonic

27
Q

if a muscle stays in its stretched state the ________ reflexes disappear rapidly

A

phasic

28
Q

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

A

tonic

new

29
Q

a muscle is slowly stretched by what type of force

A

external

30
Q

external force examples

A

weight

gravity

31
Q

during the tonic stretch reflex, first it _______ the stretching only due to its passive elasticity

A

resists

32
Q

during TSR at a certain threshold recruitment of alpha motoneurons begins, leading to ______ force development

A

active

33
Q

the whole TSR curve is called a ________

A

tonic stretch reflex characteristic

34
Q

what activities induce the TSR

A

walking

jumping

35
Q

7 steps to the tonic stretch reflex

A
  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
Q

the TSR is a major mechanism that defines what

A

the viscoelastic properties of muscles, joints, and limbs

37
Q

what can the TSRs threshold be viewed as

A

a control variable manipulated by the brain

38
Q

what is NOT exclusively manipulated by the brain

A

muscle activation levels
forces
changes in joint angles

39
Q

Muscle activation, forces, and changes in joint angles emerge with equal participation from __________

A

central commands (brain) and external loads (reflexes)

40
Q

high frequency muscle vibration leads to a slow reflexive increase in muscle force

A

tonic vibration reflex

41
Q

TVR _________ afferent information

A

suppresses

42
Q

TVR is accompanied by a suppression of _________ reflexes in the same muscle

A

monosynaptic

43
Q

the suppression of the H reflex is of a _______ origin

A

presynaptic

44
Q

muscle vibration can induce __________ of different muscles of the same limb

A

reflexive contractions

45
Q

_________ receive mixed information from afferents originating from different receptors

A

Ia and Ib interneurons

46
Q

a stimulation of the flexor reflex afferents in a limb induces what two things

A
  • a reflex response in flexor muscles of the limb

- a crossed extensor reflex in extensor muscles of the contralateral limb

47
Q

the _______ is unknown in polysynaptic reflexes because there are so many which makes it hard to trace

A

reflex loop

48
Q

polysynaptic reflexes involve ______ muscles

A

distant

49
Q

reflexes that have longer latency, slow, steady state character

A

polysynaptic

50
Q

four examples of polysynaptic reflexes

A
  • flexor reflex
  • crossed extensor reflex
  • tonic stretch reflex
  • tonic vibration reflex
51
Q

what happens at the threshold of the tonic stretch reflex

A
  • recruitment of alpha motoneurons in muscle that is lengthening to produce force to counter the movement
  • as muscle lengthens, muscle spindles are activated
52
Q

what happens as the muscle continues to lengthen

A

more motoneurons recruited and muscle force is increased

53
Q

a person steps on a sharp object. which two reflexes would be excited and how would they work together

A
  • flexor reflex on affected leg to pull it up

- cross extensor on contralateral leg to support

54
Q

what happens to the H and T reflex when vibration is applied

A

they are suppressed

EP 4703 Unit 2 (3 decks)

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