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Neuroscience > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What percentage of the CNS is made of neurons?

A

50-60%

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2
Q

T/F Neurons contain most of the same organelles as any other cell of the body

A

True

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3
Q

What is the process by which materials move from the cell body along microtubules and neurofilaments?

A

Axoplasmic transport

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4
Q

What percentage of the total neuronal surface area available for synaptic contact is made up of dendrites?

A

Over 90%

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5
Q

What cells in the cerebellum have over 1000 dendrites?

A

Purkinje cells

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6
Q

What is the average number of synaptic contacts/inputs made by an average neuron?

A

7000

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7
Q

Myelin is formed by what type of cells?

A

Glial cells

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8
Q

What is at the nodes of Ranvier?

A

Voltage-gated sodium and potassium channels for propagation of the action potential.

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9
Q

What are axon collaterals?

A

branches of axons which enable the neuron to activate more than one effector cell at a time

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10
Q

What is an effector cell?

A

another neuron, muscle, or a gland

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11
Q

What do axon terminals contain?

A

synaptic vesicles of chemical substances (NT)

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12
Q

What is the name of a neuron that is acted upon? What is the name of a neuron that causes and action?

A

Post-synaptic neuron.

Pre-synaptic

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13
Q

What determines the nature of the action of a neuron on another cell type?

A

The post-synaptic receptor

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14
Q

T/F Since the post-synaptic receptor determines the effect on a cell, an NT may be excitatory for some cells and inhibitory for other cell types.

A

True

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15
Q

Where are bipolar neurons found?

A

in special sensory systems (eye, auditory and vestibular systems)

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16
Q

Which neuron types make up the peripheral sensory afferents?

A

Pseudounipolar neurons

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17
Q

Where are iterneurons found exclusively?

A

within the CNS.

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18
Q

T/F Interneurons account for about 99% of neurons

A

True

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19
Q

What do nuclei form in the CNS?

A

Large clusters of gray matter (cell bodies)

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20
Q

What are some terms that describe bundles of axons?

A

Tract, fasciculus, and lemniscus

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21
Q

What is formed by several tracts running together?

A

Funiculus

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22
Q

T/F Neuron may be described by the action of their NT

A

True

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23
Q

What are the four types of CNS glial cells?

A

Oligodendrocytes, Astrocytes, ependymal ells, and microglia

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24
Q

Which type of Schwann cells are crucial for inducing nerve sprouting?

A

non-myelinating type of schwann cells

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25
Q

What is a glioblastoma multiforme?

A

an astrocytoma that often spreads extensively from one side of the brain to the other via the corpus callosum with lethal consequences

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26
Q

Schwannomas and neurofibromas are tumors of the PNS. Which type is easily removed?

A

Schwannomas

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27
Q

Why are neurofibromas more difficult to remove?

A

They infiltrate nerve fibers

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28
Q

The outside of cells has a predomination of what charged ion? Inside of cell?

A

Na+. K+

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29
Q

Which ion has the ability to move INTO the cell passively?

A

Na+

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30
Q

How do ion pumps help restore the concentration gradients of ions?

A

By pumping Na+ OUT and K+ into the cell

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31
Q

What are graded potentials also known as?

A

Local potentials

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32
Q

What is the process called when a cell membrane depolarizes a small amount?

A

EPSP

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33
Q

What is the process called when a cell membrane hyperpolarizes a small amount?

A

IPSP

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34
Q

What are the two types of summation in graded potentials?

A

Temporal and spatial

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35
Q

Where do graded potentials usually occur?

A

In unmyelinated synapse regions

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36
Q

What do astrocytes do in the CNS?

A

Help to remove some excess K+ ions

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37
Q

What are plateau potentials?

A

Relatively prolonged (but not slow) depolarizations mediated by calcium entry into the neuron. Contribute to myotonia, gongenita, spasticity

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38
Q

What region of the neuron has the lowest threshold for excitation and highest density of voltage-sensitive Na+ channels?

A

Axon hillock

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39
Q

Where is the initiation of action potentials in sensory neurons? In motor neurons?

A

In the periphery.

In the CNS

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40
Q

Unmyelinated axons have Na+ and K+ channels all along the length of the axon, where as myelinated axon has voltage gate Na+ channels concentrated at the _________

A

Nodes of Ranvier

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41
Q

What is the conduction velocity along myelinated axons? How many times faster is it than on unmyelinated axons?

A

120 meters/sec. As much as 50 times faster

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42
Q

What is the conduction in the opposite direction of action potentials?

A

Antidromic conduction (elicited by machanical or electrical stimulation of the neuron)

43
Q

What is synaptic transmission?

A

Electrical signal in the presynaptic neuron is converted into a chemical signal at the synapse, and then into an electrical signal again in the post-synaptic neuron

44
Q

Synapses in the soma tend to be ______ where as those on dendrites tend to be excitatory

A

inhibitory

45
Q

What are some amino acids that can act as NTs?

A

glycine, glutamate, aspartate.

46
Q

What does an action potential do to the membrane of the axon terminal as it propagated down the axon?

A

It depolarizes the membrane

47
Q

Where do voltage-gated calcium channels open?

A

in the axon terminal

48
Q

What does entry of calcium into the axon cause the synaptic vesicles to do?

A

move to the synaptic terminal.
fuse their membranes with that of the presynaptic terminal.
release their contents into the synaptic cleft

49
Q

IPSP make the membrane more _______ where as EPSPs make it less _______

A

polarized/negative

50
Q

What are three ways that synaptic transmission can be terminated?

A

NTs diffuse away.
NTs are inactivated by specific enzymes
Nts may be taken back into the presynaptic axon terminal

51
Q

Where does an IPSP never occur?

A

A synapse between an alpha motor neuron and its post-synaptic cells, the skeletal muscle cell. It all happens in the CNS before it ever gets out to the muscle

52
Q

What is the EPSP at the NMJ called?

A

endplate potential

53
Q

What is excitation-contraction coupling?

A

For every action potential in an alpha motor neuron, there will be an action potential in the muscle cell innervated by that motor neuron

54
Q

What are the five broad classes of NTs?

A

Monoamines, cholinergic, amino acids, neuropeptides, non-traditional NTs

55
Q

What are some monoamines?

A
  1. Catecholmines such as norepinephrine, epinephrine, and dopamine.
  2. Serotonin.
56
Q

Acetylcholine is a _______ NT

A

cholinergic

57
Q

What are three common amino acid NTs?

A

GABA, glycine, and glutamate

58
Q

What are some neuropeptide NTs?

A

endorphins, calcitonin gene-related peptide, and substance P

59
Q

Whare some non-traditional NTs?

A

NO and CO2

60
Q

Generally NTs that open Na+ channels are ________ and those that open chloride channels are inhibitory

A

excitatory

61
Q

What are the targets for most pharmocological interventions?

A

NTs and their receptors

62
Q

What are the two broad classes of receptors?

A

Ionotropic and Metabotropic

63
Q

What are ionotropic receptors?

A

form channel in membrane thru which ions can pass, NTs bind and cause a conformation change in the transmembrane proteins to open ion channels

64
Q

What are metabotropic receptors?

A

G-protein coupled receptors.
Initiate range in chemical changes.
NT binds to receptor and change its shape and this activates the G-protein

65
Q

What can activated G-proteins do?

A

open ion channels.
activate genes
modulate intracellular calcium concentrations

66
Q

What NTs are of interest?

A

ACh, norepinephrine, dopamine, serotonin, glutamate, GABA

67
Q

When does fertilization occur?

A

12-24 hours after ovulation

68
Q

When does 2-cell stage occur? 4-cell stage (second cleavage)?

A

30 hours

40 hours

69
Q

When is the 16-cell stage reached?

A

3 days

70
Q

What does the inner cells mass, the embryoblast give rise to? What is the outer cell mass called and when does it form?

A

the embryo proper.

blastocyst at five days

71
Q

When does implantation occur?

A

day 6

72
Q

When are the endoderm and ectoderm formed?

A

at the end of the second week

73
Q

When does a layer of mesoderm become visible?

A

3rd week

74
Q

What are the five stages of Nervous System Development?

A

Neurulation, Cellular proliferation, neuronal migration, cytodifferentation and axonal elongation, maturation of synaptic contacts and refinement

75
Q

When does neurulation occur? From what layer does the nervous system begin to form?

A

At about 16 days of gestation.

Ectoderm

76
Q

What are the layer of a trilaminalr embryo?

A

Endoderm, mesoderm, ectoderm

77
Q

What does the endoderm become?

A

viscera

78
Q

What does the mesododerm become?

A

heart and circulatory system, muscle, bone, and meninges and the notochord

79
Q

What does the notochord develop into?

A

nucleus pulposis of the intervertebral disks

80
Q

What does the ectoderm become?

A

CNS structures, adrenal medulla, and skin

81
Q

What is the progressive formation of CNS structures?

A

Neural plate, neural groove, neural folds, neural tube, neural crest

82
Q

When should the rostral portion of the neural tube close? Caudal portion?

A

by day 27. by day 30

83
Q

What does the neural crest form?

A

sensory ganglia of spinal and cranial nerves

84
Q

What is the name of the congenital malformation where the rostral neuropore fails to close?

A

Anencephaly

85
Q

What is the name of the congenital malformation where the caudal neuropore fails to close?

A

Spina bifida - oculta, meningocele, myelomeningocelef

86
Q

What is the Arnold-Chiari malformation?

A

part of the cerebellum and caudal brainstem herniate through the foramen magnum

87
Q

What are the three functional layers neural plate and neural tube formation?

A

Germinal zone, intermediate zone, marginal zone (aka cortical plate)

88
Q

The germinal zone is the ______ most layer consisting of pluripotent neuroepithelial cells

A

inner

89
Q

Newly divided cells in the germinal layer can be referred to as what?

A

Neuroblasts, glioblasts. Neuroblasts use the glioblasts to help them migrate out of the germinal zone

90
Q

What do neuroblasts use to migrate from the germinal zone to the brains outer layers?

A

use fibers from radial glial cells and their own axons

91
Q

What do glial cells secrete to help neurons find the correct pathway?

A

Chemical attractants

92
Q

What do neuron cells have that helps them bind to glial cells?

A

adhesion molecules

93
Q

What is tangetial migration?

A

Moving from one radial glia to another of following axons

94
Q

Incomplete neuron migration can be caused by what factors?

A

radiation, genetic mutations, drugs such as alcohol and cocaine. Or childhood epilepsy

95
Q

What are the regions of the spinal cord during formation?

A

sulcus limitans, alar plate, basal plate

96
Q

What forms can plasticity take at the synapse?

A

Increased/decreased number of synaptic vesicles.
Increased/decreased number/density of postsynaptic membrane receptors.
Change in the type of postsynaptic membrane receptor
Formation of novel synapses on the same cell
Pruning of established synapses

97
Q

In the axon, what forms can neuroplasticity take on?

A

Regenerative sprouting or collateral sprouting

98
Q

In the soma, what forms can neuroplasticity take on?

A

Altered gene expression

99
Q

Functionally, what does nueroplaticity result in?

A

Strengthening of connections between neurons.
Weakening or loss of connections between neurons.
Novel connections between neurons that previously were not connected by a synapse.
Cells becoming healthier or taking on new functions

100
Q

What is Hebb’s Law?

A

Cells that fire together, wire together - the synapse of two neurons is strengthened when their temporal activation is concurrent

101
Q

Which two NTs are only metabotropic?

A

Norepinephrine and dopamine

102
Q

The ionotropic receptor for ACh is ______. For meabotropic it is both _______ and ______

A

excitatory.

Excitatory and inhibitory

103
Q

T/F the actions of GABA are inhibitory for both ionotropic and metabotropic receptors

A

True

Neuroscience (10 decks)

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