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Physiology > Section 3 Lecture 2 > Flashcards

Section 3 Lecture 2 Flashcards

1
Q

Over-learned, over practiced skills:

A

race car driving, etc. Actually reaction time, voluntary, learned movement in response to a stimulus

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2
Q

Circuitry already present in the development of the system:

A

reflex

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3
Q

T or F? Reflex strength (gain) can be modulated.

A

T. by descending pwys (stronger, weaker, or totally suppressed)

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4
Q

T or F? Some reflexes require input from the cortex

A

T

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5
Q

Reflexes are mediated by:

A

s.c., brainstem, and cortex

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6
Q

The reflex strength or gain may be modulated by:

A

PWs from brainstem or cortex (stronger, weaker, or totally suppressed)

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7
Q

Where does the circuitry for movements reside in humans?

A

in the s.c.

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8
Q

T or F? Transection leads to the loss of conscious sensation from below the cut, the ability to generate voluntary movement below the cut, and reflexes below the cut

A

F. Still have spinal reflexes, true to the first 2

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9
Q

Even after s.c transection you still have:

A

spinal reflexes (mm., MNs, S input from the body, and spinal interneurons

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10
Q

Which is the simplest of the reflexes?

A

The stretch reflex

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11
Q

What is the stimulus for the stretch reflex?

A

stretch of a m.

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12
Q

Stretch response leads to contraction of:

A

the same m.

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13
Q

How is the stretch reflex clinically tested?

A

by tapping on a tendon, which mechanically stretches the m.

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14
Q

In the deep tendon reflex, does the tendon participate in the generation of the force for movement?

A

No

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15
Q

Clinical name of the stretch reflex:

A

deep tendon reflex

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16
Q

The stretch reflex demonstrates what principle about mm.?

A

The m. works to keep the m. length constant

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17
Q

Pwy of the stretch reflex circuit:

A

Afferent from 1a m.s. into the s.c., excitatory synapse on a-MN whose axon goes back to the same m. monosynaptic,very short-latency reflex

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18
Q

Does the 1a fiber in the stretch reflex make an excitatory or inhibitory synapse on the a-MN?

A

Excitatory

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19
Q

Resistance to passive stretch of a m.:

A

muscle tone

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20
Q

Test m. tone:

A

passively stretch the extensor (passive: because it comes from the outside, not voluntary movement, there is some resistance to that)

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21
Q

What does the stretch reflex resist?

A

Passive stretch of a muscle

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22
Q

the circuitry in the stretch reflex:

A

the 1a fiber branches, 1 brach to sp. interneuron which inhibits MNs going to the antagonist m., another to the agonist to flex m. to maintain the same m. length

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23
Q

As one m. contracts, the antagonist m. relaxes. This is called:

A

reciprocal innervation

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24
Q

Explain the involvement of the cortex and BG in the stretch reflex:

A

Cortex or BG have no involvement, at the level of the s.c .only

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25
Q

Flexion-crossed extension reflex:

A

Hand down on hot surface, flexion of all flexors in every joint of the limb and simultaneous relaxation of the extensors, stimulus can be over only a few mm^2 of skin

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26
Q

transection pt:

A

won’t feel stimulus but the reflex occurs

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27
Q

How does info in the flexion-crossed extension pwy get to the brain?

A

It doesn’t, stays in s.c.

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28
Q

Purpose of crossed extension reflex:

A

To stabilize the uninjured side of the body

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29
Q

T or F? The Flexion crossed extension reflex involves 1 interneuron.

A

F. many

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30
Q

What type of innervation is involved in the flexion-crossed extension reflex?

A

double reciprocal innervation

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31
Q

Where are PGs in the human body?

A

s.c. and brainstem: ie. chewing and swallowing

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32
Q

T or F? The PGs of the s.c. function completely independent of the brain.

A

F. Brain turns and off and modulates

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33
Q

Reflex that involves mm. + s.c. + some nuclei in the brainstem:

A

the tonic neck reflexes

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34
Q

tonic neck reflexes:

A

pos of head coded by proprioceptors in the neck (via CN, not s.c.), position of head, determines the position of the limbs

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35
Q

T or F? The position of the head in the tonic neck reflex is determined by the s.c.

A

F. via CN (sending info regarding neck position, right?)

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36
Q

Where do the nuclei reside that are involved in the tonic neck reflex?

A

The brainstem

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37
Q

What determines the positon of the head in the tonic neck reflex?

A

proprioception in the neck

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38
Q

Response of the fore- and hindlimbs when looking up:

A

Fore: extend, hind: flex

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39
Q

Repsonse of the fore- and hindlimbs when looking down:

A

Fore: flex, hind: extend

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40
Q

Pose of a baby while laying on back with one arm outstretched and the other flexed:

A

fencer’s pose

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41
Q

Which limb extends and which flexes in the fencer’s pose?

A

Ipsilateral limb extends, contra flexes (in relation to what?)

42
Q

All reflexes are under the control of what portions of the brain?

A

Cortex and brainstem

43
Q

T or F? Lower levels of the motor system control the reflexes.

A

F. Higher

44
Q

Motor signals descend via

A

Pyramidal or CSP tract

45
Q

T or F? Flexion reflexes are reactionary and not able to be modulated consciously.

A

F. Frontal lobe can override.

46
Q

Cell bodies in (this) desc to s.c. and modify or adjust reflex strength.

A

the brainstem

47
Q

Can the flexion reflex be suppressed?

A

Yes

48
Q

What portion of the brain can override the flexion reflex?

A

frontal lobe

49
Q

What sense modalities trigger the flexion reflex?

A

nociception and touch (mechanoreceptor, light touch stimulus ie, hand under bed, spider crawls over, retract quickly)

50
Q

The circuitry for the tonic neck reflexes is here:

A

brainstem and s.c.

51
Q

Where is all motor fxn in babies?

A

brainstem and s.c., non-my fibers from the descending tracts (cortico-spinal tracts)

52
Q

Who are tonic reflexes seen in?

A

babies and people w damage to higher levels of M system

53
Q

What can lead to the reemergence of the tonic reflexes?

A

Damage to higher levels of M system

54
Q

T or F? Adults display tonic reflexes.

A

F. only babies or after damage to higher level MNs

55
Q

What is spinal shock:

A

what you see imm after s.c. transection, complete absence of reflexes below the level of the cut. Circuitry is there, reflexes vanish wo descending input

56
Q

T or F? Reflects never return after spinal shock.

A

F. Spinal reflexes gradually return, recovery time varies bw species.

57
Q

What does the time required for the return of reflexes after spinal shock depend upon?

A

The greater the importance of the higher levels of motor system (the more complex the CNS), the longer to recover from spinal shock

58
Q

Hyperreflexia:

A

stronger than normal reflexes

59
Q

What causes Babinski’s sign?

A

damage to MC or pyr tract (or being a baby)

60
Q

What’s the name of the response elicited w Babinski’s sign?

A

extensor plantar response

61
Q

Why do babies exhibit Babinski sign?

A

the descending pathways are not yet myelinated

62
Q

T or F? If a baby fans their toes with stimulation applied to the bottom of their feet, there is damage to the pyramidal tract.

A

F. Babinski’s Sign is normal in babies

63
Q

Why does abnormal m. tone come about?

A

bc of abnormal descending control of the stretch reflex

64
Q

Damage to MS:

A

altered control of the stretch reflex (check)

65
Q

M. tone too low:

A

hypotonia

66
Q

Conditions that cause hypotonia:

A

Down’s Syndrome, Proder Willy syndrome (hungry all the time)

67
Q

Hypertonia is aka:

A

rigidity - stroke pts. and cerebral palsy

68
Q

Down’s syndrome is assoc w (hyper/hypo) tonia.

A

hypo

69
Q

Prader-Willi syndrome is assoc w (hyper/hypo) tonia.

A

hypo

70
Q

Cerebral Palsy is assoc w (hyper/hypo) tonia.

A

Hyper

71
Q

Stroke is assoc w (hyper/hypo) tonia.

A

hyper

72
Q

Decerebrate rigidity:

A

cut midbrain bw the sup and inf colilculi, inc tone in extensors of all 4 limbs and tail and head (antigravity position)

73
Q

What does too much excitability in the stretch reflex cause?

A

Tone in all extensor limbs

74
Q

A cut where would result in decerebrate rigidity?

A

Intercolicular transectin of midbrain

75
Q

A cut where would result in decorticate rigidity?

A

MC or Pyramidal tract

76
Q

Decorticate rigidity:

A

damage on one side effects contralateral side, inc tone in flexors of the arms and the extensor of the leg

77
Q

Decorticate:

A

inc tension in flexors of arm ( of ipsilateral side?) and extensors of leg of contralateral side

78
Q

Decerebrate:

A

inc tension in all extensors

79
Q

Will a stroke lead to decerebrate or decorticate rigidity?

A

decorticate

80
Q

5 things spasticity includes:

A

inc m. tone (rigidity), hyperactive stretch reflexes, clonus (tap tendon and you will get more than one kick), clasp-knife reflex, Babinski sign

81
Q

Clasp knife reflex:

A

try to extend the arm of person with decorticate rigidity: resistance at first, then melts away and arm extends easily

82
Q

What cause the melting away (inhibition) of stretch reflex?

A

afferent pain fibers of the mm.

83
Q

CP:

A

not a single disease, damage to M systems that occurs at or just before birth, not seen w car accidents w a person in their 20’s

84
Q

What do the subclasses of CP reflect?

A

The involvement of cortex, cerebellum, or BG

85
Q

T or F? CP is a single disease entity.

A

F

86
Q

T or F? Birth anoxia leads to CP.

A

F.

87
Q

Pregnancy issues that can lead to CP:

A

infection, rubella, CMV, toxin exposure, alcohol, herpes, toxoplasmosis, premature birth

88
Q

Causes of CP arising from the baby:

A

genetic defect, intracranial hemorrhage, head trauma

89
Q

Other problem associated w CP besides M damage:

A

intellectual disability, sensory problems (vision, hearing), or seizure disorders

90
Q

Cortical involvement in CP can lead to:

A

spasticity

91
Q

dangerous, shortening of tendons, limbs frozen in place, leads to arthritis and other joint issues:

A

Contractures

92
Q

Txs for spasticity and rigidity in CP:

A

(hyperactive stretch reflexes): cut the dorsal 1a fiber roots from the affected mm. or Rx baclofen

93
Q

What is Baclofen?

A

inhibitory transmitter to tx spasticity in CP, could be continuously infused into the s.c. via an implantable pump to inhibit the stretch reflex

94
Q

Rigidity can be a symptom of:

A

MS, PD (BG disorder), CP

95
Q

How is Parkinson’s Disease different in terms of rigidity?

A

Affects both flexors and extensors

96
Q

CP pts may have these dental issues:

A

abnormal m. tone in mouth, jaw, tongue, may cause problems with alignment, bruxism, drooling, sialorrhea (impaired swallowing), dental enamel defects

97
Q

Questions to ask a potential pt with CP:

A

What type of CP and what are the limitation of M control? ambulatory vs not? Involuntary moves? Frequent falls and trauma? Seizures? IQ/behavior?

98
Q

impaired swallowing:

A

sialorrhea

99
Q

Are the interneurons involved in reflexes excitatory or inhibitory?

A

Neither. Somewhere in bw

100
Q

This reflex is a result of the stretch reflex:

A

Flexion-crosses extension reflex

101
Q

What is the name of the normal response to stimulus on the bottom of the foot?

A

plantar flexion

102
Q

How to fix decrebrate rigidity:

A

cut DR’s (1a fiber m. spindle input), rigidity melts away

Physiology (55 decks)

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