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Flashcards in Module B-01 Deck (82):
1

2 major cell types in CNS and PNS

1) Neurons
2) Glia

2

Functions of Glia

-Supportive
- Protective (cushion and ideal chemical environment)
-Regulatory
-Electrically Insulated

3

Define Neurites

axons and dendrites

4

Describe neuronal cell membrane

- Phospholipid bilayer with ion channels , receptors and other protein complexes

5

Describe neuronal nucleus

bilayered porous membrane that contains DNA

6

Nissl substance consists of_______ and produces______

RNA granules ; Proteins

7

Location of Nissl substance

Cell body and proximal regions of dendrites

8

describe mitochondria

Bilayered organelle involved in energy generation

9

Function of Golgi apparatus

-vesicular packaging
-modification and transport of products of Nissl substance

10

Lysosomes

scavenger vesicles loaded with degratory enzymes

11

3 types of Cytoskeleton filaments

1) Microtubules
2) Neurofilaments/Intermediate Filaments
3) MIcrofilaments

12

Functions of Cytoskeleton filaments

-Change shape during cell growth and regenration
-Maintain shape in Mature cell
-Transport of material

13

Microtubules are polymers of___________

alpha, Beta and Gamma tubulin

14

How do microtubules grow?

-addition of tubulin dimers which are the cross linked by Tau protein (alzheimer's)

15

Function of microtubules

Forms Tracts for the 2 axonal transport

16

Anterograde transport aka

orthograde

17

Protein involved in anterograde axonal transport is ________ and retrograde is ________

Kinesin; Dynein

18

In which direction does Kinesin move on along the microtubules?

towards the positive end of the micortubule and becomes inactivated at nerve ending

19

What type of proteins are Kinesin and Dynein?

ATPases

20

In which direction does Dynein move on along the microtubules?

towards negative end of microtubule and becomes inactivated at the soma

21

Function of Retrograde transport

-NGF transport after endocytosis at teh nerve terminal towards the soma
- recycled vesicles and lysosomes

22

3 Types of Neurofilaments/Intermediate filaments

GFAP (glial fibrillary acidic protein)
nestin
vimentin

23

Function of Neurofilaments/Intermediate filaments

create scaffolding of cytoskeleton

24

Structure of Neurofilaments/Intermediate filaments

Highly polymerized with little turnover

25

Number of Neurofilaments/Intermediate filaments in neurons is dependant on _________

Axonal Diameter (radial development)

26

_________ is similar to myosin of muscle in that it has binding sites for large structures

Kinesin

27

Actin is a type of __________

Microfilament

28

Function of Microfilament

- participates in advancement of Growth Cone
- synaptic vesicle endocytosis during vesicle recycling (actin)

29

Location of Microfilaments

forms a network just below the cell membrane

30

How is dendritic transport different from axonal?

microtubule are in mixed orientation for selective movement to dendrites rather than axons

31

Rate of Axoplasmic flow

1mm/day

32

neuron with multiple dendrites

Multipolar

33

Multipolar neuron with long axons are called ________ and those with short axons are called ________

Golgi type I (Motor) ; Golgi type II (inhibitory)

34

Neurons with elongated cell body and two processes

Bipolar

35

Function of Bipolar

Special sensory systems like retina and CN 8 (visual and auditory)

36

neurons with 2 axonal processes that diverge from a stalk of the cell body

Pseudounipolar

37

Example of Pseudounipolar

sensory neurons that form the Dorsal Root ganglia and cranial nerve ganglia

38

Class A fibers

Myelinated neurons

39

Class C fibers

Unmyelinated neurons

40

Myelination _______ speed of conduction

increases

41

categorization of neurons according to myelination

Class A and C

42

Categorization of neurons according to Axonal diameter

Class I, II, III and IV

43

Class I

Largest diameter and most rapid conducting

44

Class II and III

intermediate diameter and intermediate conduction speeds

45

Class IV

Smallest, unmyelinated and slowest (Class C)

46

How do inhibitory neurons inhibit

release transmitter that polarize and stabalize membrane

47

What dictates whether a neuron has inhibitory or excitatory effect?

Receptors on postsynaptic neurons , not the transmitter

48

6 types of glia

- Astrocytes
- Microglia
- Oligodendrocytes
- Ependymal cells
- Tanycytes
- Choroidal epithelial cells

49

Most numerous cell type in CNS

Astrocytes

50

Functions of Astrocytes

-Maintain ionic homeostasis
- Maintain synaptic homeostatis
- Regulate cerebral blood flow
- Protect neurons from oxidative damage
- Supply lactate to glucose-deprived neurons
- Direct differentiation of neuronal precursors (releasing growth factors)
- Release cholesterol (a component of the lipid structure of membranes)
- Increase numbers of synapses
- Release gliotransmitters
- Uptake of excess K+ through ion channels

51

What transmitters do astrocytes take up at the synaptic cleft?

glutamate, glycine and monoamines

52

What Gliotransmitters do Astrocytes release?

Glutamate, D-serine and ATP

53

Which 2 types of glial cell forms Gliotic scar (gliosis) during Brian and Spinal cord damage?

Astrocytes and ependymal cells

54

Effect of high extracellular K+ levels on neuron

Depolarizes the neuron

55

What is spatial buffering or potassium siphoning?

When astrocytic K+ ion channels that take up the excessive extracellular ions for shunting to neighboring astrocytes via gap junctions

56

__________ are Neuronal, astrocytic and oligodendrocytic progenitors

Radial Glia

57

2 locations where Radial glia persist

- Bergman glia in cerebellum
- Müller cells of the retina

58

Function of Microglia

Immunocompetent and phagocytic
- Protect neurons from micro-organisms and toxic effects of cellular debris
- Secrete neurotrophic or neuron survival factors upon activation
- contribute to initiation of pathological neuronal degernation
- Release cytotoxic molecules

59

Types of cytotoxic molecules released by microglia

o Proinflammatory cytokines
o Reactive oxygen intermediates
o Proteases

60

_________ myelinate axons of CNS neurons

Oligodendrocytes

61

Function of ependymal cells

Produce CSF
form CSF-brain barrier
produce neurons and glial cells after stroke

62

Location of Ependymal cells

walls of ventricles

63

Function of Choroid plexus epithelial cells

- Secrete cerebrospinal fluid (CSF)
- transfer molecules from blood into CSF

64

Tanycytes are derived from

Radial Glia

65

Function of Tanycytes

Interface between CSF and Blood
allow sampling by homeostatic areas

66

Where do Schwann cells originate from

neural crest cells (both myelinated and unmyelinated)

67

Functions of Schwann cells

- myelination in PNS
- clearing cellular debris by phagocytosis

68

What happens to schwann cells of damaged axons

regress to immature state to support regeneration

69

Enteric glial cells are similar to _______

astrocytes

70

Where are satellite glia found?

in sensory, sympathetic and parasympathetic ganglia

71

what type of glia are schwann cells, satellite and enteric glial cells?

PNS glia

72

Function of satellite cells

surround neurons to to regulate chemical environment

73

What happens during axonal transection of PNS

o Distal axonal segment degenerates
o Proximal axonal segment may form sprouts
o Schwann cells Proliferate, forming a guide tube
 Release nerve growth factors, encouraging axonal regeneration
 Re-myelinate the regenerating axon
 Target cells may die unless reinnervated within denervated
cells may die after 3 weeks

74

Rate of axon growth in remyleination

about 2 mm/day

75

Define Chromatolysis

Post traumatic neuronal swelling and dilution of of organelles

76

Anterograde transneuronal degeneration

death of denervated (postsynaptic) cell or neuron

77

Retrograde transneuronal degeneration

death of the cell presynaptic to the damaged cell

78

Wallerian degeneration

degeneration of the disconnected axon and terminal

79

Why doesn't regeneration occur in CNS?

- not enough NGF is secreted by the glial cells
- oligodendrocytes don't form guide tubes as Schwann cells
- Gliotic scars block axonal regrowth

80

All Tumors of the PNS are_________

Schwannomas

81

__ of tumors of brain and ____ of spinal cord are glial origin

50%; 25%

82

2 demyelinating autoimmune diseases

- Guillain Barre Syndrome (peripheral demyleinating)
- Multiple Sclerosis