Neuron Structure Flashcards

1
Q

Dendrite or axon?

Can be single or multiple extensions of the cell body

A

Dendrite

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2
Q

Dendrite or axon?

Can contain all cytoplasmic organelles except for the Golgi apparatus, especially in proximal dendrites.

A

Dendrite

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3
Q

Dendrite or axon?

Tapers in a proximo-distal direction

A

Dendrite

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4
Q

Dendrite or axon?

can branch profusely and can have spines; spines contain spine apparatus and receive the bulk of the synapses

A

Dendrite

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5
Q

Dendrite or axon?

Almost never myelinated

A

Dendrite

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6
Q

Dendrite or axon?

Usually ramify close to the cell body

A

Dendrite

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7
Q

Dendrite or axon?

Responds with graded depolarization or hyperpolarizatino that decrements spatially and temporaly; some can generate action potentials

A

Dendrite

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8
Q

Dendrite or axon?

Major receptive site of synapses (postsynaptic), but may also be presynaptic

A

Dendrite (e.g. dendrodendritic synapses)

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9
Q

Dendrite or axon?

Structurally absent but functionally present in unipolar cells

A

Dendrite

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10
Q

Dendrite or axon?

Major energy consuming portion of a neuron

A

Dendrite

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11
Q

Dendrite or axon?

Single extension from the cell body or from a dendrite

A

Axon

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12
Q

Dendrite or axon?

Can contain most cytoplasmic organelles except for Golgi apparatus, rough ER, and ribosomes

A

Axon

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13
Q

Dendrite or axon?

Trunk stays cylindrical, can branch profusely

A

Axon

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14
Q

Dendrite or axon?

Terminals enlarge to form boutons that contain synaptic vesicles

A

Axon

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15
Q

Dendrite or axon?

Varicosities can occur along the trunk for en passant synapses

A

Axon

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16
Q

Dendrite or axon?

Can be myelinated or unmyelinated

A

Axon

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17
Q

Dendrite or axon?

Can ramify close to or far away from the cell body

A

Axon

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18
Q

Dendrite or axon?

APs are generated at the initial segments

A

Axon

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19
Q

Dendrite or axon?

Major effector site of synapse (presynaptic), but may also be postsynaptic (e.g. axoaxonal synapse)

A

Axon

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20
Q

Dendrite or axon?

May be absent (e.g. amacrine cells)

A

Axon

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21
Q

Dendrite or axon?

Energy consumption is low in the axon trunk, but may be low, moderate, or high in the terminals

A

Axon

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22
Q

What is the perikaryon?

A

Soma or cell body

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23
Q

Active chromatin

A

Euchromatin

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24
Q

Nissly substance is absent in which portion of the axon?

A

Axon hillock

25
Q

Initiation of action potentials occurs here.

A

Initial segment of axon

26
Q

The surface membrane of the axon

A

Axolemma

27
Q

En passant synapses

A

Varicosities

28
Q

Synaptic end-feet

A

Synaptic boutons (boutons terminaux)

29
Q

The axoplasm lacks ________.

A

Ribosomes or RER

30
Q

Sensory ganglion neurons have which structure type?

A

Unipolar or pseudounipolar

31
Q

Retina & olfactory neurons have which structure type?

A

Bipolar

32
Q

Purkinje cells of the cerebellum, pyramidal neurons of the cerebral cortex, and motor neurons of the spinal cord have which structure type?

A

Multipolar (most common)

33
Q

Which Golgi type has long axons and projection neurons?

A

Golgi type I

34
Q

Which Golgi type has short axons and interneurons?

A

Golgi type II

35
Q

What are lipfuscin granules?

A

“indigestible” lysosomal material with pigmented inclusions

36
Q

The most abundant protein in neurons.

A

Microfilaments

37
Q

Microfilaments:

Single-stranded helix of globular ______ that binds to ATP and polymerize to form filamentous ______.

A

Microfilaments:

Single-stranded helix of globular G actin that binds to ATP and polymerize to form filamentous F actin.

38
Q

Describe the treadmilling effect.

A

Microfilaments have a fast growing plus end and a slower growing minus end.

39
Q

Are microfilaments polar?

A

Yes, they are polar ATPases.

40
Q

What is the role of cytochalasins?

A

They depolymerize F actin.

41
Q

What is the role of phalloidin?

A

It stabilizes F actin.

42
Q

What do cytochalasins and phalloidins both do?

A

They both block the turnover of microfilaments and threaten cell viability.

43
Q

Are neurofilaments polar?

A

No, nonpolar

44
Q

Where are microfilaments present?

A

Present in cytoplasm throughout the neuron, also associated with the plasma membrane

45
Q

Where are neurofilaments present?

A

Present in the cytoplasm of cell bodies, dendrites, and axons

46
Q

Where are microtubles or neurotubles present?

A

Present in cytoplasm of cell bodies, dendrites, and axons

47
Q

In axons, the microtuble (+) ends are pointed where?

A

Away from the soma

48
Q

Kinesin is mainly for transport toward which end of microtubles?

A

Plus-end (away from soma, anterograde)

49
Q

MAP-2 is present only in _________.

A

Dendrites

50
Q

Dynein is mainly for transport toward which end of microtubles?

A

Minus-end (toward soma, retrograde)

51
Q

Axoplasmic flow (slow axonal transport) moves only in which direction?

A

Anterograde

52
Q

Actin, metabolic enzymes, and calmodulin (Ca++ binding proteins) are transported by:

A

axoplasmic transport, faster component (up to 10 mm/day)

53
Q

Components of microtubles and neurofilaments and soluble proteins are transported by:

A

Axoplasmic transport, slower component (0.2-2.5 mm/day)

54
Q

Fast anterograde transport (orthograde) is blocked by:

A

Colchicine

55
Q

Subcellular organelles are transported by:

A

fast anterograde (orthograde) axonal transport

56
Q

Fast anterograde/retrograde transport requires:

A

ATP

57
Q

Kinesin has how many heavy and light chains?

A

2 heavy chains which bind to both microtubles and ATP

2 light chains which bind to other cellular components

58
Q

Dynein (MAP-1C) has how many heavy and light chains?

A

2 or 3 heavy chains (form globular ATP bind motor domains)

Variable numbers of light chains (bind to other cell components)

59
Q

True or false:

The rate of dendritic transport is faster than axonal transport.

A

False

Rate and components are similar to those of axonal transport.