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Neurosurgery Boards > Neurophysiology > Flashcards

Neurophysiology Flashcards

1
Q

Bell-Magendie law

A

sensory axons enter DRG and motor exit ventral root

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2
Q

What are sensory Ia fibers?

A

Ia-Aalpha-Fast large, stimulated by muscle length and velocity of contraction. Receptor is primary spindle afferents

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3
Q

What are sensory Ib fibers?

A

Ib-Aalpha also- Fast, stimulated by muscle tension. Receptor is golgi tendon

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4
Q

What are sensory II fibers?

A

Smaller AB and Agamma. Stimulated by muscle length, touch, pressure (flower spray). Receptor is spindle, meissner, merkel, paccini, Ruffini

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5
Q

What are sensory III fibers?

A

A delta. Stimulated by temperature, light touch, stretch, sharp pain. Receptor- Free nerve endings

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6
Q

What are sensory IV fibers

A

C. Smaller. Stimulated by slow burning pain and temperature. Receptor- unmyelinated free nerve endings

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7
Q

What are A alpha motor fibers?

A

rapid, spinal alpha motor neuron efferents to extrafusal musculature

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8
Q

What are A gamma motor fibers?

A

smaller, gamma motor neurons to intrafusal muscles (spindles and golgi)

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9
Q

What are B motor fibers?

A

Preganglionic autonomic fibers

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10
Q

What are C motor fibers?

A

unmyelinated ventral root sensory axons (violate Bell-Magendie law) but cell bodies are in DRG (L5-S3). Conduct pain and temperature to pelvic viscera

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11
Q

What do free nerve endings mediate?

A

Stretch (A-d), Temperature (A-d,C), pain (A-d, C), light touch (A-d)

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12
Q

What is glabrous skin?

A

No hair and contains Meisner’s and Merkel’s

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13
Q

What are Meissner’s corpuscles?

A

Detect Touch: Small fields, rapid adaptation

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14
Q

What are Merkel’s disk?

A

Touch and Pressure: Small fields, slow adaptation

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15
Q

What receptors are in deep subcutaneous skin?

A

Pacinian and Ruffini

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16
Q

What are Pacinian Receptors?

A

Vibration: Large fields, rapid adaptation

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17
Q

What are Ruffini Receptors?

A

Heavy pressure and stretch: Large fields and slow adaptation

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18
Q

What makes up the neuromuscular junction?

A

Alpha motor neuron, muscle fiber, and surrounding Schwann cell

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19
Q

What is neuregulin?

A

Induces Ach receptor gene transcription –> nicotinic receptor synthesis at NMJ

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20
Q

What are sarcomeres?

A

Solitary contractile unit of muscle cell made up of several myofibrils. Connected to each other at Z disk.

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21
Q

What is desmin?

A

Connects myofibrils

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22
Q

What is dystrophin?

A

Anchors desmin to muscle cell sarcolemma

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23
Q

What is actin?

A

Thin filaments that radiate from Z disk toward center of sarcomere. Makes up the I band

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24
Q

What and where is myosin?

A

Thick filament b/t actin found at A Band

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25
Q

What is the H Zone?

A

Region of A band where myosin is not overlapped by actin. Centered on M line

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26
Q

What two regions shorten with contraction?

A

H zone and I Band.

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27
Q

What is the state of actin in the resting state?

A

Tropomyosin and Troponin Complex (I,C,T) bind actin. Ca release from SR (sarcoplasmic reticulum) -> Troponin C binds 4 Ca molecules -> Relieves inhibition of myosin binding site on actin

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28
Q

What are Red muscle fibers?

A

Slow twitch, Type I

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29
Q

What are Type IIA muscle fibers.

A

Fast fatigue resistant fibers (have some aerobic capacity)

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30
Q

What are Type IIb muscle fibers

A

Fast fatigable (Large stores of glycogen and are anaerobic)

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31
Q

Describe cardiac muscle?

A

striated, mononuclear, joined end to end by intercalated disc with gap junctions

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32
Q

Describe smooth muscle

A

Sheets of elongated spindle-shaped cells without myofibrils. Larger movements over longer distances.

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33
Q

How does smooth muscle contract?

A

Ca binds calmodulin –> MLCK –> phosphorylates myosin II light chain-> Contracts

34
Q

What are intrafusal muscles?

A

afferent sensory fibers that are found in the myofibril that send information about contraction velocity and lengthening to CNS. Important for fine motor control

35
Q

What innervates intrafusal muscles?

A

A gamma fibers (contractile regions) and Ia/II in non-contractile regions. Muscle firing decreases firing of muscle spindles

36
Q

What are the two types of Muscle spindle fibers?

A

Nuclear chain fibers (primary anulospiral and flower spray) and Nuclear bag fibers

37
Q

What is the Golgi tendon organ?

A

sensory receptors in series with extrafusal muscles and associated with muscle-tendon junction. Detect Contraction and lengthening

38
Q

What fibers mediate the deep tendon reflex?

A

Ia -> monosynaptic connection c alpha motor neuron –> DTR. Also inhibits firing of antagonist muscles

39
Q

What are sustenacular cells?

A

support cells involved in taste

40
Q

Sweet taste

A

Metabotropic receptor –> increased cAMP and depolarization through inactivation of K channels

41
Q

Bitter taste

A

Increase IP3

42
Q

Salty taste

A

direct diffusion of Na and K through ion channels on cell

43
Q

Sour taste

A

direct diffusion of H and blocks K channels

44
Q

Umami

A

metabotropic glutamate receptor

45
Q

How is the sense of smell mediated?

A

Small transmitter G-proteins. Neurons synapse in the mitral and tuft cell in glomeruli –> olfactory tract –> cortex (no thalamic relay)

46
Q

How are granule and periglomerular cells involved in smell?

A

inhibitory interneurons from subependymal zone refine smell

47
Q

How is smell consciously perceived?

A

Via mediodorsal thalamus -> orbitofrontal cortex

48
Q

What is the fovea?

A

REgion of the retina with the highest visual acuity

49
Q

Cones

A

High acuity, low sensitivity, color

50
Q

Rods

A

Low acuity, high sensitivity, b&w. Sensitive because many rods project to one ganglion cell (convergent)

51
Q

Photoreceptors are maintained in the _____ state secondary to _____

A

resting, high levels of cGMP. Light –> 11-cis retinal –> all trans retinal –> hydrolyzes cGMP which leads to hyperpolarization of photoreceptor by closing cGMP-gated Na channel

52
Q

What is rhodopsin?

A

visual pigment of photoreceptors?

53
Q

What is the pathway of visual information to the LGN?

A

Bipolar cells –> ganglion cells (axons of the ganglion cells make up optic nerve) –> Optic Nerve –> Chiasm–> Tract–> LGN

54
Q

What are the layers of the LGN?

A

Layers 1,4,6- Contralateral retina; Layers 2,3,5- ipsilateral retina

55
Q

Amacrine cells

A

Contribute to surround component of ganglion cell receptive fields

56
Q

Ganglion cells respond best to _____

A

Contrast

57
Q

What are X(P Cells)

A

Ganglion cells that Respond to steady state light, small field, details

58
Q

What are Y (M cells)

A

Ganglion cells that respond to motion, large fields

59
Q

What are Muller cells?

A

glial cells c long processes (inner and outer retinal layer)

60
Q

What is the stria of Gennari?

A

Primary visual cortex (17). Axons in Layer 4.

61
Q

_____ connects to TM and ____ to the oval window.

A

Malleus, Stapes

62
Q

What muscles and nerves dampen sound?

A

Tensor tympani (V3)/TM and stapedius (VII)/oval window

63
Q

Where are the hair cells of Corti located?

A

Basilar membrane

64
Q

What is the stria vascularis?

A

Secretes endolymph (high K, low Na) into the Scala media

65
Q

What mediates hair cell depolarization?

A

K influx from endolymph –> Voltage gated Ca activation

66
Q

Inner hair cells

A

numerous synaptic contacts with spiral ganglion nerve afferents. Responsible for sound transduction: loss –> deafness

67
Q

Outer hair cells

A

Freq selective: loss –> decrease 30 db hearing

68
Q

What makes up the vestibular system?

A

Semicircular canals, utricle, saccule. All are filled with endolymph and surrounded by perilymph

69
Q

What are the otolithic organs?

A

Utricle and saccule

70
Q

Deflection of hair cells toward kinocilium –> _____?

A

depolarization

71
Q

What is the macula of the utricle/saccule and what is it’s orientation in the neutral position?

A

Location of hair cells. Utricle- Horizontal, Saccule- Vertical (the sack hangs vertically)

72
Q

Where are the hair cells found on the semicircular canals?

A

Ampulla and are held in place by cupula (gelatinous membrane that bends in response to endolymph motion). Synapse with Scarpa’s ganglion –> Vestibular nerve –> Vestibular nuclei –> Fastigial nucleus of cerebellum

73
Q

Which nucleus of the cerebellum receives projects from the vestibular nuclei?

A

Fastigial

74
Q

What are the circumventricular organs?

A 
POSS MAN
Pineal
organum vasculosum of lamina terminalis
subforniceal
subcommissural organ (only one with intact BBB)
median eminence of hypothalamus
area postrema (only paired)
neurohypophysis
75
Q

What are markers of early ischemic injury?

A

Increased glutamate and aspartate (increased Na influx)

76
Q

What are markers of late ischemic injury?

A

Ca influx via NMDA –> Ca –> PLC –> Fatty acid –> free radicals and NO

77
Q

What is the brain CMRO2

A

3ccO2/100g/min

78
Q

What is the brain CMRglu

A

5ccglc/100c/min

79
Q

Schwann cells are derived from ____ ?

A

Neural crest cells

80
Q

What does atropine block? What is Spared?

A

Muscarinic receptors. Only the parasympathetic postganglionic synapses are affected. The autonomic ganglia and NMJ are spared.

81
Q

What does curare block?

A

Nicotinic receptors (autonomic ganglia and NMJ)

Neurosurgery Boards (10 decks)

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