Neurocytology I Flashcards Preview

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Flashcards in Neurocytology I Deck (90):
1

The PNS and CNS are composed of

Neurons and Support cells

2

Ganglia (groups of neuron cell bodies), nerves, nerve endings, receptors on neurons or on peripheral targets (skeletal muscle, smooth muscle, etc)

Peripheral Nervous System (PNS)

3

What are two examples of PNS support cells?

Satellite cells and Schwann cells

4

Nuclei (groups of neuron cell bodies) or cortices (sheets of neuronal cell bodies), nerves, nerve endings, receptors on neurons (or on glia)

Central Nervous System

5

What are four support cells of the CNS?

Oligodendrocytesm Astrocytes, Ependymal Cells, and Microglia

6

The first evidence of a nervous system is detected during the

3rd week in development

7

The ectoderm in the dorsal midline thickens to form the

Neural Plate

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The neural plate gives rise to the

CNS

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Develops from the region lateral to the neural plate and gives rise to the PNS

Neural Crest

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Develops into the brain and spinal cord (CNS)

Neural tube

11

The neural tube initially consists of an

Epithelium with cilia

12

Give rise to neurons and glia of the CNS

Epithelium

13

Provide guidance to migrating neurons and growth factor support

Glial cells

14

It is important to note that neurons stop dividing when they

Differentiate

15

Can not regenerate if injured by environmental toxins, stroke, or unknown factors leading to degenerative diseases

Neurons

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Functions to receive, integrate, conduct, and transmit information

Neuron

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Neurons vary tremendously in appearance and in

Transmitter content

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The dendritic and somal membrane serves and integrating function by

Summing excitatory and inhibitory information that reaches neuron

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In a neuron, information is received at contact points called

Synapses

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Has the highest concentration of voltage sensitive ion channels and the lowest threshold for firing action potentials

Initial axonal segment

21

Presynaptic neurons communicate signals with post synaptic neurons via

Synapses

22

Synthesizes proteins and contains the Nissl Bodies (ribosomes and RER)

Neuronal cell body (soma)

23

The cell body provides protein to support the

Axon

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The axon is entirely dependent on the cell body for essential materials such as

Proteins

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The axon lacks

Nissl bodies

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The extensions of the cell body and contain most of the organelles of the cell body

Dendrites

27

Cytoskeletal elements are found throughout the neuron including in the

Axon

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Contains cytoskeletal elements but no Nissl bodies

Axon

29

Axonal transport can occur in which two directions?

Anterograde and Retrograde

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From cell body to the axon terminal

Anterograde

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From axon terminal to the cell body

Retrograde

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Associated with anterograde AND retrograde transport

Fast axonal transport

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Moves such constituents as synaptic vesicles, endosomes, and mitochondria

Fast axonal transport

34

Anterograde transport can also be slow and transport things such as elements of the cytoskeleton and proteins such as

Clathrin

35

Can also be slow

Anterograde transport

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Fast transport in the anterograde or retrograde direction is associated with

Microtubules

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The "motor" for anterograde transport and in some rare cases, for retrograde transport

Kinesin

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The "motor" for retrograde transport

Dynein

39

Although it has been most studied in axons, transport also occurs in

Dendrites

40

Play a support function and help regulate axonal growth

Intermediate filaments and microfilaments

41

Associated with synaptic vesicle release

Microfilaments

42

Spacially discrete membrane specializations which function to mediate communications between neurons and target cells

Synapses

43

What are the two types of synapses?

Electrichal and chemical

44

Relatively rare in humans and correspond to gap junctions

-seen exclusively during development

Electrical synapses

45

In electrical synapses, small pores allow ions and molecules like ATP or small signalling molecules to pass from

One cell to the next

46

Made up of a presynaptic element, a synaptic cleft, and a post synaptic element

Chemical Synapse

47

Utilizes neurotransmitter molecules

Chemical synapses

48

The area in the presynaptic neuron where there is an accumulation of neurotransmitter-filled vesicles

Active zone

49

Neurotransmitters are released from vesicles in the presynaptic neuron into the synaptic cleft by way of

Exocytosis

50

Vesicles collect in active zones and release their contents when

Action potentials invade the terminal

51

Vesicle release from the presynaptic neuron into the synaptic cleft requires

Ca2+ influx

52

Binds neurotransmitter vesicles to actin filaments and other components of the cytoskeleton

Synapsin I

53

Synapsin I is phosphorylated by a

Ca2+/calmodulin dependent kinase

54

What happens when synapsin I is phosphorylated by Ca+2 / calmodulin dependent protein kinase?

Vesicles released from actin and move to active zone

55

Docking and fusion of vesicles with presynaptic membrane appears to be associated with multiple proteins including

VAMPs and t-SNAREs

56

Calcium sensing proteins such as synaptotagmins are thought to regulate the

Docking and fusing process

57

What are the four fates of neurotransmitters in the synaptic cleft that have not bound to the postsynaptic neuron?

1.) degraded by enzymes
2.) taken back up by pre-synaptic terminal
3.) taken up by glia
4.) diffuse away

58

After transmitter release, exocytotic vesicles remain associated with the plasma membrane and are

Recycled

59

After endocytosis, coated vesicles pinch off from the presynaptic membrane, the coat is lost, and the vesicles fuse with the

Early endosome

60

In some cases vesicles may be refilled with transmitter without going through the

Early endosome pathway

61

Can not be used indefinitely. Some is retrogradely transported and degraded by lysosomes in the cell body

Vesicle membrane

62

Neurotransmitter is synthesized and stored in vesicles. Then an action potential invades the presynaptic neuron and causes

Depolarization of presynaptic terminal resulting in Ca2+ influx

63

Causes vesicles to fuse with presynaptic membrane

Ca2+ influx

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Causes excitatory or inhibitory postsynaptic potential that changes the excitability of the post synaptic cell

Postsynaptic Current

65

Some diseases and chemicals with which we may come into contact can affect aspects of

Synaptic transmission

66

Results in impaired vesicle recycling

Congenital myasthenic syndromes

67

Attacks presynaptic Ca2+ channels

LEM

68

Affect SNARE proteins involved in vesicle fusion

Botulinum and tetanus

69

We focused on synapses that are between an axon and a dendrite. There are also

Axo-somatic, axo-axonic, and dendro-dendritic synapses

70

There are synapses with a cleft of 400nm and no recognizable densities in the

ANS

71

A highly polarized cell

Neuron

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In most cases, each region of a neuron is specialized to contribute to the neuron's function of

Receiving, integrating, and transmitting information

73

Generally the regions of the neuron that receive synaptic signals are

-synaptic signals can be found on other parts of the neuron

Dendrites

74

If the neuron is cut off from its source of trophic substances or if an axon is cut off from the cell body it is in danger of

Dying

75

In the PNS, groups of neuronal cell bodies are called

Ganglia

76

In the CNS, groups of neuronal cell bodies are called

Nuclei

77

Provide structural support for migrating neurons and also provide growth factors

Glial cells

78

The cell body (soma) can also be referred to as the

Trophic locus of the cell

79

Increase surface area of dendritic branches

-are extended in an active cell and retracted in an inactive cell

Dendritic Spines

80

What are the three main types of dendritic spine presynaptic membranes?

1.) Ion channels
2.) G-protein linked receptors
3.) Kinase receptors

81

Affect polarity of membrane

Ion channels

82

The cell body (trophic locus) of a neuron has an extensive

RER and ribosomes (Nissl bodies)

83

Nissl bodies extend into

Dendrites

84

Organneles move through the axon on microtubules, but in order to reach the terminal, they are transferred to

Actin filaments

85

Gap junctions that are typically only present during development

Electrical synapses

86

Invaginations in the post synaptic membrane across from vesiccles

Junctional folds

87

Phosphorylates synapsin I and allows docked vesicles to move from the actin filament to the presynaptic membrane

Ca2+/calmodulin dependent kinase

88

Produced by target cells and released from postsynaptic membranes where they are taken up in vesicles at pre-synaptic membranes

Growth factors

89

Growth factors are taken up in vesicles called signaling endosomes, which exhibit which type of transport?

Retrograde transport

90

If a lesion causes the cell body to lose it's growth factors it undergoes

-Nissl bodies move to periphery and disintegrate

Chromatolysis

Decks in Structure and Function Test 1 Class (61):