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Boards: Neurology + Ophthalmology > Neuro Physiology > Flashcards

Neuro Physiology Flashcards

1
Q

What are the functions of glial cells? (5)

A
  • produce myelin sheets
  • modulate growth of damaged or developing neurons
  • buffer extracellular neurotransmitter and K+ concentrations
  • forms contacts between neurons
  • immune responses of the nervous system
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2
Q

Where do afferent sensory versus efferent motor axons exit or enter the spinal cord?

A

afferent sensory - enter through the dorsal roots

efferent motor - exit through the ventral roots

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3
Q

What part of the brain does the hypothalamus belong to?

A

Diencephalon - forebrain

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4
Q

Name these structures

A
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5
Q

What are the 3 protective layers of the CNS?

A
  • Pia mater - single layer fibroblasts
  • Arachnoid - spiderweb appearance, thin layer fibroblasts (subarachnoid space with CNS between pia mater and arachnoid
  • Dura mater - thick layer fibroblasts
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6
Q

What is axoplasmic transport?

A

transport of proteins/macromolecules produced in the neuron cell body and carried through the axon to the presynaptic terminals

needed transprot because axons are not able to produce proteins themselves / lack ribosomes

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7
Q

What are PNS versus CNS glial cells called?

A
  • PNS Swann cells
  • CNS Oligodendrocytes
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8
Q

What are the indentation between myelin sheets called?

A

nodes of Ranvier

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9
Q

What is the normal resting membrane potentia of neurons?

A

-70 mV

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10
Q

Describe the differences between postsynaptic Na+ versus K+ channel opening

A

If neurotransmitter opens Na+ channels&raquo_space; moves membrane potential towards more positive&raquo_space; triggering depolarization = excitatory postsynaptic potential

If neurotransmitter open K+ channel&raquo_space; moves membrane potential more towards hyperpolarzied (i.e., more negative)&raquo_space; inhibitory postsynaptic potential

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11
Q

What is destroyed in Coonhound paralysis?

A

myelin sheets

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12
Q

Besides surgery list 4 treatment options for insulinomas

A
  • glucocorticoids - increases gluconeogenesis
  • diazoxide - inhibits insulin secretion
  • somatostatin - increases gluconeogenesis
  • streptozocin - toxic to beta cells
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13
Q

What trigger release of presynaptic vesicles?

A

increase in IC Ca++

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14
Q

What is synaptobrevin and syntaxin/SNAP-25?

A

binding proteins at the presynaptic membrane that bind and align acetylcholine filled vesicles

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15
Q

What does Ca++ bind to to cause vesicle release at the presynaptic membrane?

A

synaptotagmin

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16
Q

What receptors does acetylcholine bind to at the postsynaptic membrane in neuromuscular junctions?

A

nicotinic acetylcholine receptors

when bound - channel opens - Na+ diffuses into the cell&raquo_space; depolarizaiton&raquo_space; excitatory nerve impulse

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17
Q

List examples for these major neurotransmitter classes:

  • amino acids
  • amines
  • catecholamines
  • peptides
  • opioids
  • purines
  • gases
A
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18
Q

How does tetanus excert its effects?

A

tetanospasmin - blocks synaptic release of GABA and glycine by cleaving synaptobrevin (vesicle binding protein)

i.e., blocks release of inhibitory neurotransmitters

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19
Q

What are intrafusal versus extrafusal muscle fibers innervated by?

A

extrafusal - alpha motor neurons
intrafusal - gamma motor neurons

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20
Q

What neurons typically malfunction to cause LMN signs. Where are these neurons located and what do they innervate?

A

alpha motor neurons

cell bodies + dendrites located in the CNS (ventral horn spinal cord or brainstem if CN)

axons innervate the extrafusal skeletal muscle fibers

21
Q

What are the 4 hallmarks of LMN signs?

A
  • paralysis or paresis - flaccid
  • loss of reflex arch - loss of segmental and intersegmental reflexes
  • muscle atrophy - within days of the injury
  • changes on electromyography within a few days
22
Q

where are upper motor neurons located?

A

completely in the CNS&raquo_space; influence the lower motro neurons&raquo_space; send axons down the spinal cord or into the brain stem to control LMNs

23
Q

What are the hallmarks of UMN injuries/disease?

A
  • inappropriate or abnormal movement (spinal cord injury often causes weakness, brain orignin rigidity, circling, seizures, inappropriate movements)
  • no muscle atrophy - LMN still intact
  • retained but exaggerated segmental reflexes - loss of UMN inhibitory control
  • normal electromyogram
24
Q

Where does the motor neuron unit exit the spinal cord?

A

ventral horn of spinal cord gray matter

25
Q

With LR and LH weakness and proprioceptive deficits, what are differentials for neurolocalizaiton?

A
  • right motor cortex
  • right corticospinal tract
  • left cervical spinal cord
26
Q

When assessing physiologic nystagmus, what reflex is assessed?

A

Vestibuloocular reflex

27
Q

What are the hallmark signs of cerebellar disease?

A
  • wide-stance ataxia
  • dysmetria (inappropriate measure of muscle contractions) - exaggerated goose-stepping
  • asynergia
  • Intention tremors
28
Q

Where do the sympathetic and parasympathetic nervous systems originate?

A

sympathetic - thoracolumbar spinal cord

parasympathetic - brainstem and sacral spinal cord

29
Q

What 3 tissues does the autonomic nervous system affect?

A
  • smooth muscles
  • glandular tissue
  • cardiac muscles
30
Q

Which cranial nerves are part of the parasympathetic system?

A
  • oculomotor (CN III)
  • facial (CN VII)
  • glossopharyngeal (CN IX)
  • vagus (CN X)
31
Q

What nerves are formed by the sacral part of the parasympathetic nervous system?

A

pelvic nerves

32
Q

How is norepinephrine removed from the synpatic cleft?

A

reuptake by the presynaptic neuron

33
Q

How are norepinephrine and epinephrien removed from the circulation?

A

enzymatic breakdown
* catechol-O-methyltransferase
* monoamine oxidase

highest cc in liver and kidneys

34
Q

What are the two different receptors stimulated by acetylcholine?

A

Muscarinic acetylcholine receptor
* G-protein couple
* target cells of postganglionic parasympathetic neurons and cholinergic postganglionic neurons of the sympathetic nervous system

Nicotinic receptors
* ligand-gated ion channels
* at synapses between autonomic preganglionic and postganglionic neurons
* at somatic neuromuscular junctions

35
Q

Why does sympathetic stimulation typically last longer than parasympathetic stimulation?

A

because of circulating norepinephrine and epinephrine

36
Q

Describe how urine storage is facilitated

A

facilitated mainnly by the sympathetic nervous system
* lumbar splanchnic nerves - inhibits contraction of the destrusor muscle
* inhibit parasympathetic postganglionic neurons that would otherwise cause detrusor contraction
* contracts smooth muscle internal sphincter (neck of bladder)
* somatic motor neurons&raquo_space; external sphincter contraction (urethralis muscle)

37
Q

Describe how urine voiding is facilitated

A
  • contraction of the detrusor muscle via parasympathetic nervous system (pelvic nerves)
  • inhibition of sympathetically mediated storage reflex

both controlled by the pontine micturition center (PMC)

PMC can be overriden by conscious control

38
Q

What structures must be intact for a normal direct PLR response?

A
  • retina
  • CN II
  • CN III
  • brainstem
  • iris
39
Q

How is aqueous humor formed?

A

active transport of Na, Cl, HCO3- into the posterior chamber&raquo_space; draws in water

flows from posterior into anterior chamber due to pressure gradient

absorbed into the venous system at the angle between the cornea and the iris

40
Q

Where is CSF formed?

A

choroid plexus of the ventricles

41
Q

List 3 functions of the CSF

A
  • cushions the brains against trauma
  • helps maintain a consistent EC environment for neurons
  • removes potentially harmful cellular metabolites
42
Q

What are the 4 ventricles?

A
  • 2 lateral ventricles, left and right
  • third ventricle at the midline of the diencephalon
  • fourth ventricle: between cerebellum and dorsal surfac of hindbrain
43
Q

How does blood pressure of CSF pressure affect CSF formation?

A

independent - formation is almost constant

44
Q

Name 3 drugs that could reduce CSF production/volume

A
  • acetazolamide (carbonic anhydrase inhibitor)
  • furosemide
  • PPIs - proton-pump inhibitors (reduce NaKATPase activity in the choroid plexus)
45
Q

What characteristics facilitate the BBB selectivity?

A
  • tight junctions
  • no open clefts (usually present in capillaries in other organs)
46
Q

What molecules can cross the BBB easily?

A
  • lipophilic
  • minimally protein-bound
  • small and uncharged

otherwise&raquo_space; carrier-mediated transport

47
Q

What are the parts of the neuromuscular bundle?

A
  • surrounding pericytes
  • glial astrocytic “end-feet”
  • neurons
48
Q

How can you measure CSF pressure and what is normal in dogs?

A

manometer through a needle placed in the cisterna magna

normal < 180 mm CSF

Boards: Neurology + Ophthalmology (14 decks)

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