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Neurobiology Flashcards

1
Q

function of neuroglia

A

myelination of neuronal axons, neurotransmitter uptake, neuronal growth factor synthesis, removal of extracellular debris, assistance with neuronal migration, BBB structure

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2
Q

neuroglia cells

A

microglia, astrocytes, Schwann cells, oligodendrocytes

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3
Q

function of astrocytes

A

regulate the balance of electrolytes (mainly potassium) in the extracellular space, provide nutrient support to neurons, stimulate endothelial cells to form tight junctions that compose the BBB, regulate neurotransmitter concentration, divide in response to injury (astrocytes or gliosis) and have limited phagocytic capacity

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4
Q

types of astrocytes

A
  1. fibrous astrocytes -> primarily in white matter

2. protoplasmic astrocytes -> primarily in gray matter

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5
Q

Bergmann cells

A

specialized astrocytes which surround and support the Purkinje cells of the cerebellum and Muller cells of the retina

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6
Q

oligodendrocytes

A

responsible for myelination of axons; single oligodendrocyte myelinations MULTIPLE axons

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7
Q

Schwann cells

A

responsible for PNS myelination; single Schwann cell myelinates one axon

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8
Q

microglia

A

derived from macrophages (MESODERMAL ORIGIN) and subsequently migrate into the CNS; phagocytosis and antigen presentation

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9
Q

are dendrites myelinated?

A

no

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10
Q

what is the name of the structure on a neuron that extends in a tubular fashion from the cell soma

A

axon hillock

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11
Q

what is the most excitable portion of the neuron

A

axon hillock

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12
Q

why is the axon hillock the most excitable portion?

A

high concentration of sodium channels

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13
Q

what structure is devoid of Nissel substance?

A

axon hillock

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14
Q

axon

A

efferent component of the neuron that conducts action potentials from the soma or axon hillock

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15
Q

unipolar neuron

A

simplest neuron; found only in the autonomic nervous system of vertebrates

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16
Q

bipolar neuron

A

associated with special senses (olfactory, vision, auditory, vestibular)

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17
Q

pseudounipolar neuron

A

two processes that fuse into one; comprise sensory ganglia of cranial nerves and spinal nerves (e.g. dorsal root ganglia)

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18
Q

multipolar neuron

A

most prevalent type of neuron; multiple dendrites

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19
Q

the ependymal cells that line the roof of the third and fourth ventricles, and the choroidal fissure of the lateral ventricles is called…

A

tela choroidea

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20
Q

tela choroidea

A

specialized secretory epithelium (choroid plexus) that synthesizes approximately 70% of the CSF

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21
Q

BBB of choroid plexus is unique….

A

epithelial instead endothelial

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22
Q

proteins and phospholipids that are destined for secretion are initially synthesized in the

A

rough endoplasmic reticulum

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23
Q

Rough ER sends products to the

A

Golgi complex

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24
Q

what happens in the Golgi complex

A

modifies proteins by adding polysaccharides, and processing includes glycosylation (O-linked and N-linked), proteoglycan formation, attachment of fatty acids, and sulfating of tyrosine and sugar residues

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25
protein involved in fast anterograde transport
kinesin and ATP; 400 mm/day
26
drugs that interfere with microtubule structure and disrupt fast anterograde transport
vinblastine and colchicine
27
component A
slower than fast anterograde transport; 0.2 to 2.5mm/day; utilizes dynamic (GTP-dependent)
28
Component B
2-4mm/day; uses actin/myosin motor complex in the transport of cytosolic proteins, actin and spectrin
29
protein involved in retrograde axonal transport
dynein and ATP; 400mm/day
30
two types of synapses in the nervous system
electrical and chemical
31
electrical synapse
direct spread of action potential from the presynaptic neuron to the post-synaptic neuron; these neurons have direct cytoplasmic continuity with GAP JUNCTIONS CALLED CONNEXONS WITH PROTEIN SUBUNITS CALLED CONNEXINS
32
is electrical synapse unidirectional or bidirectional? slow or fast?
Fast; bidirectional
33
chemical synapse
more prevalent; pre and post-synaptic neuron separated by synaptic cleft; synaptic vesicles with neurotransmitters
34
is chemical synapse unidirectional or bidirectional? slow or fast?
unidirectional; slower than electrical
35
creation of acetylcholine
from choline and Acetyl CoA by enzyme choline acetyltransferase
36
what neurons use acetylcholine?
1. spinal cord motor neurons at NMJ 2. all PRE-ganglionic autonomic neurons 3. all POST-ganglionic parasympathetic neurons 4. POST-ganglionic sympathetic neurons to sweat glands 5. nucleus basalis of Meynert
37
acetylcholine is metabolized by what enzyme
acetylcholinesterase
38
Dopamine, epinephrine and norepinephrine are all metabolized from the same molecule...
tyrosine
39
rate limiting enzyme in dopamine and norepinephrine synthesis
tyrosine hydroxylase; tyrosine -> L-DOPA
40
synthesis of dopamine from L-dopa via what enzyme
Aromatic amino acid decarboxylase
41
what prevents dopamine uptake into the synaptic vesicle
reserpine
42
where does norepinephrine synthesis take place?
in the synaptic vesicle
43
dopamine to norepinephrine via what enzyme
dopamine B-hydroxylase
44
where is norepinephrine found?
locus ceruleus, most post-ganglionic sympathetic neurons, pineal gland
45
norepinephrine uptake is blocked by what...
cocaine
46
norepinephrine is metabolized by what enzyme
catechol-O-methyl transferase (COMT) and monoamine oxidase (MAO)
47
synthesis of epinephrine from norepinephrine occurs in the adrenal medulla via what enzyme?
phenylethanolamine-N-methyl transferase
48
rate limiting enzyme in serotonin synthesis
tryptophan to 5HTP via tryptophan hydroxylase
49
5HTP to serotonin via what enzyme
5-hydroxytryptophan decarboxylase
50
describe process of synaptic vesicle exocytosis
depolarization -> calcium/calmodulin-dependent phosphorylation of synapse proteins release synaptic vesicle -> targets docking site at active zone of terminal bouton -> protein within wall called vesicle SNARE (v-SNARE or synaptobrevin) then binds to a target-SNARE (t-SNARE, syntaxin) -> protein complex fuses with wall of the synaptic vesicle and terminal bouton resulting in NT release
51
what does tetanus toxin cleave?
synaptobrevin
52
what does botulinum toxin cleave?
t-SNARES and v-SNARES
53
what subunit on G proteins interacts with effector enzymes?
alpha subunit
54
cholera toxin activates what G protein?
Gs
55
pertussis toxin activates what G protein?
Gi
56
G proteins activate adenylate cyclase to produce?
cyclic AMP
57
cAMP interacts protein kinase A and subsequently phosphorylates what...
serine and threonine residues on target proteins
58
nitric oxide is generated from what amino acid
arginine via nitric oxide synthase
59
nitric oxide synthase is activated by ca2+/calmodulin-dependent enzyme after stimulation of what receptor?
NMDA via glutamate
60
does nitric oxide stimulate cAMP or cGMP?
cGMP
61
what type of receptors do acetylcholine bind to?
nicotinic and muscarinic
62
subunits to nicotinic cholinergic receptors
5 subunits: two alpha, one beta, one gamma, one delta (a2byd)
63
alpha subunit binds how many ACH molecules?
one
64
how many ACH molecules are needed for activation of the channel?
two
65
a-bungarotoxin
binds the alpha subunit, effectively inhibiting nicotinic cholinergic channels
66
inhibitors of nicotinic cholinergic receptors
hexamethonium (ganglionic), succinylcholine (depolarizing), and D-tubocurarine (non-depolarizing)
67
subunits that make up muscarinic cholinergic receptors?
2 subunits: alpha and beta
68
what inhibits and stimulates muscarinic cholinergic channels?
inhibits -> atropine and scopolamine | stimulates -> bethanechol, carbachol, pilocarpine, methacholine
69
GABA-A subunits
5 subunits -> 2 alpha, 2 beta, 1 gamma
70
what subunits in GABA-A binds GABA, barbiturates, benzodiazepines?
GABA -> alpha, beta and gamma barbiturates -> alpha and beta benzodiazepines -> gamma
71
GABA-B channel
increases K+ conductance, thus generating inhibitory post-synaptic potential; activated by agonist baclofen
72
glycine channels
chloride channels that generate IPSP
73
glycine is synthesized in what cells?
Renshaw cells (spinal cord)
74
glycine channels are blocked by
strychnine
75
glycine release is inhibited by what toxin
tetanus
76
all norepinephrine receptors are metabotropic receptors that use G proteins and the second messenger....
cAMP
77
two sites of neurogenesis in the adult brain
1. subependymal zone in the lateral wall of the lateral ventricles -> migrate through glial tubules to the olfactory bulb 2. hippocampus -> subgranular layer of the dentate gyrus
78
what is the resting membrane potential in the neuron?
between -60 and -70mV; closest to K+ equilibrium potential (-75mV)
79
Na=K+ pump
3 Na out, 2 K in
80
how can you increase the conduction velocity of an axon?
1. increase axon diameter 2. increase transmembrane resistance 3. decrease internal resistance 4. decrease membrane capacitance 5. myelination
81
proteins and phospholipids that make up myelin
1. basic myelin protein 2. myelin-associated glycoprotein 3. proteolipid 4. peripheral myelin protein 22
82
myelin increases what to increase conduction velocity
increases transmembrane resistance and reduces membrane capacitance
83
process of nerve regeneration after transection
synaptic transmission failure -> distal axon degeneration and phagocytosis (Wallerian degeneration) -> neuronal soma undergoes chromatolysis (peripheralization of rER and increased protein synthesis)-> end of proximal axon swells -> regeneration occurs when axons sprouts grow from the end of the proximal axonal segment and enter tissue remnants of distal stump
84
do larger axons have larger stimulation thresholds?
no, lower stimulation thresholds
85
larger axons are more sensitive to what....
hypothermia, compression and anoxia
86
local anesthetics induce conduction blocks in large or small axons?
both; smaller axons initially, then larger
87
Bell-magendie law
all sensory axons enter the dorsal root of the spinal cord, while all motor axons exits via the ventral root
88
Group I (Aa) fibers
largest, fastest conducting fibers (70-120m/s) Two subgroups: 1) Ia -> primary muscle spindle afferent 2) Ib -> afferents from Golgi tendon organs
89
Group II (AB, Ay) fiber s
slower (30-70m/s); represent muscle spine secondary (flower-spray) afferents and cutaneous touch and pressure afferents
90
Group III (Ad) fibers
even slower (4-30m/s); conduct information regarding temperature, light touch and fast/sharp pain
91
Group I to Group III fibers. are all....
myelinated
92
Group B fibers
preganglionic autonomic fibers found only in the ventral root
93
Group C fibers
unmyelinated fibers that are much slower (0.4-2m/s) and mediate temperature and slow/burning pain.
94
Aa fibers
very rapid; spinal cord alpha motor neuron efferents to extrafusal musculature
95
Ay fibers
slower; impulses from y-motor neurons to intrafusal musculature (muscle spindles and GTO)
96
What fibers violate the Bell-Magendie Law?
C fibers
97
Meissner's corpuscles
- transmit flutter via AB fibers - small receptive fields - rapid adaptation
98
Merkel's disk receptors
- transmit pressure via AB fibers - small receptive fields - slow adaptation
99
Pacinian corpuscles
- transmit vibration via AB fibers - large receptive field - rapid adaptation
100
Ruffini endings
- sense skin stretch and transmit this modality via AB fibers - large receptive fields - slow adaptation

Neurosurgery Flash Cards (4 decks)

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