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Neurophysiology Flashcards

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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
What is the H Zone?
Region of A band where myosin is not overlapped by actin. Centered on M line
26
What two regions shorten with contraction?
H zone and I Band.
27
What is the state of actin in the resting state?
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
28
What are Red muscle fibers?
Slow twitch, Type I
29
What are Type IIA muscle fibers.
Fast fatigue resistant fibers (have some aerobic capacity)
30
What are Type IIb muscle fibers
Fast fatigable (Large stores of glycogen and are anaerobic)
31
Describe cardiac muscle?
striated, mononuclear, joined end to end by intercalated disc with gap junctions
32
Describe smooth muscle
Sheets of elongated spindle-shaped cells without myofibrils. Larger movements over longer distances.
33
How does smooth muscle contract?
Ca binds calmodulin --> MLCK --> phosphorylates myosin II light chain-> Contracts
34
What are intrafusal muscles?
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
What innervates intrafusal muscles?
A gamma fibers (contractile regions) and Ia/II in non-contractile regions. Muscle firing decreases firing of muscle spindles
36
What are the two types of Muscle spindle fibers?
Nuclear chain fibers (primary anulospiral and flower spray) and Nuclear bag fibers
37
What is the Golgi tendon organ?
sensory receptors in series with extrafusal muscles and associated with muscle-tendon junction. Detect Contraction and lengthening
38
What fibers mediate the deep tendon reflex?
Ia -> monosynaptic connection c alpha motor neuron --> DTR. Also inhibits firing of antagonist muscles
39
What are sustenacular cells?
support cells involved in taste
40
Sweet taste
Metabotropic receptor --> increased cAMP and depolarization through inactivation of K channels
41
Bitter taste
Increase IP3
42
Salty taste
direct diffusion of Na and K through ion channels on cell
43
Sour taste
direct diffusion of H and blocks K channels
44
Umami
metabotropic glutamate receptor
45
How is the sense of smell mediated?
Small transmitter G-proteins. Neurons synapse in the mitral and tuft cell in glomeruli --> olfactory tract --> cortex (no thalamic relay)
46
How are granule and periglomerular cells involved in smell?
inhibitory interneurons from subependymal zone refine smell
47
How is smell consciously perceived?
Via mediodorsal thalamus -> orbitofrontal cortex
48
What is the fovea?
REgion of the retina with the highest visual acuity
49
Cones
High acuity, low sensitivity, color
50
Rods
Low acuity, high sensitivity, b&w. Sensitive because many rods project to one ganglion cell (convergent)
51
Photoreceptors are maintained in the _____ state secondary to _____
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
What is rhodopsin?
visual pigment of photoreceptors?
53
What is the pathway of visual information to the LGN?
Bipolar cells --> ganglion cells (axons of the ganglion cells make up optic nerve) --> Optic Nerve --> Chiasm--> Tract--> LGN
54
What are the layers of the LGN?
Layers 1,4,6- Contralateral retina; Layers 2,3,5- ipsilateral retina
55
Amacrine cells
Contribute to surround component of ganglion cell receptive fields
56
Ganglion cells respond best to _____
Contrast
57
What are X(P Cells)
Ganglion cells that Respond to steady state light, small field, details
58
What are Y (M cells)
Ganglion cells that respond to motion, large fields
59
What are Muller cells?
glial cells c long processes (inner and outer retinal layer)
60
What is the stria of Gennari?
Primary visual cortex (17). Axons in Layer 4.
61
_____ connects to TM and ____ to the oval window.
Malleus, Stapes
62
What muscles and nerves dampen sound?
Tensor tympani (V3)/TM and stapedius (VII)/oval window
63
Where are the hair cells of Corti located?
Basilar membrane
64
What is the stria vascularis?
Secretes endolymph (high K, low Na) into the Scala media
65
What mediates hair cell depolarization?
K influx from endolymph --> Voltage gated Ca activation
66
Inner hair cells
numerous synaptic contacts with spiral ganglion nerve afferents. Responsible for sound transduction: loss --> deafness
67
Outer hair cells
Freq selective: loss --> decrease 30 db hearing
68
What makes up the vestibular system?
Semicircular canals, utricle, saccule. All are filled with endolymph and surrounded by perilymph
69
What are the otolithic organs?
Utricle and saccule
70
Deflection of hair cells toward kinocilium --> _____?
depolarization
71
What is the macula of the utricle/saccule and what is it's orientation in the neutral position?
Location of hair cells. Utricle- Horizontal, Saccule- Vertical (the sack hangs vertically)
72
Where are the hair cells found on the semicircular canals?
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
Which nucleus of the cerebellum receives projects from the vestibular nuclei?
Fastigial
74
What are the circumventricular organs?
``` 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
What are markers of early ischemic injury?
Increased glutamate and aspartate (increased Na influx)
76
What are markers of late ischemic injury?
Ca influx via NMDA --> Ca --> PLC --> Fatty acid --> free radicals and NO
77
What is the brain CMRO2
3ccO2/100g/min
78
What is the brain CMRglu
5ccglc/100c/min
79
Schwann cells are derived from ____ ?
Neural crest cells
80
What does atropine block? What is Spared?
Muscarinic receptors. Only the parasympathetic postganglionic synapses are affected. The autonomic ganglia and NMJ are spared.
81
What does curare block?
Nicotinic receptors (autonomic ganglia and NMJ)

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