L15: Nervous Tissue Flashcards

1
Q

list the stages of neural development

A
  1. neural plate
  2. neural folds
  3. neural tube
  4. neural crest tissue
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2
Q

list derivatives of neural tube

A
  1. telencephalon
  2. diencephalon
  3. mesencephalon
  4. metencephalon
  5. myelencephalon
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3
Q

3 histogenesis components of neural tube

A
  1. pseudostratified epi
  2. cortical plate
  3. marginal layer
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4
Q

neuroglial cells ?

A

non-conductive cells that support and protect entire nervous system

hold together system

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5
Q

cortical plate

A

future gray matter

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6
Q

marginal layer

A

axons

future white matter

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7
Q

nerve tissue characteristics

A
  1. irritability
  2. conductibility
  3. cellular components
  4. neurons
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8
Q

nerve tissue irritability

A

tissue specialized to receive stimuli

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9
Q

nerve tissue conductibility

A

tissue specialized to transmit impulses

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10
Q

cellular components of nerve tissue

A

neurons

neuroglial cells

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11
Q

neuron functions

A
  • -conduct impulses

- -structural and functional unit of nervous system

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12
Q

neuron parts

A

cell body = soma
dendrites
axon
terminal boutons

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13
Q

neuron cell body

A
  1. contains nucleus
  2. Nissl bodies
  3. extensive RER
  4. mitochondria
  5. lipofuscin granules
  6. ligand gated channels and local potentials
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14
Q

neuron cell body microtubules

A

called neurotubules

intermediate filaments = neurofilaments

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15
Q

lipofuscin granules

A
  • -formed from lysosomes

- -accumulate w/ age of neuron

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16
Q

gray matter

A

cells bodies, dendrites and unmyelinated axons

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17
Q

white matter

A

myelinated axons

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18
Q

dendrites

A
  1. conduct local potentials
  2. contain organelles
  3. dendritic spines
  4. branching
  5. ligand gated channels
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19
Q

axon hillock

A

origin of axon
no Nissl
associated w/ generation of ap (lowest resting potential)

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20
Q

axon

A
  1. voltage gated channels
  2. conduct ap
  3. mito and microtubules
  4. telodendrites w/ synaptic vesicles
  5. presynaptic membrane
  6. can be myelinated
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21
Q

classification of neurons due to function

A
  1. sensory or afferent
  2. motor or efferent
  3. interneurons
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22
Q

afferent neurons

A

sensory

transmit sensory info from receptors to cns

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23
Q

efferent neurons

A

motor

transmit motor info from cns to muscles/glands

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24
Q

somatic motor neuron

A

innervate skeletal muscle

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25
Q

autonomic motor neurons

A

innervate glands, cardiac and smooth muscle

divided into para or sympathetic neurons

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26
Q

interneurons

A

transmit impulses within cns and between sensory and motor neurons

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27
Q

classifying neurons by number of processes

A
  1. multipolar
  2. bipolar
  3. pseudounipolar
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28
Q

multipolar neurons

A

most common type

have a single axon and multiple dendrites

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29
Q

bipolar neurons

A

have 2 processes, one at each end of the spindle shaped neuron

associated w/ special senses such as smell and sight

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30
Q

pseudounipolar neurons

A

single process from the cell body that bifurcates into a central process

found in ganglia alongside spinal cord

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31
Q

classification of neurons by length of axon

A
  1. golgi I

2. golgi II

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32
Q

golgi I neurons

A

neurons w/ long axons that leave the gray matter they are a part of

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33
Q

golgi II neurons

A

neurons w/ short axons which ramify thru the gray matter

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34
Q

bundle of axons in pns

A

nerve

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35
Q

bundle of axons in cns

A

tract

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36
Q

ganglion

A

aggregation of cell bodies and dendrites in pns

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37
Q

nucleus

A

aggregation of cell bodies and dendrites in cns

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38
Q

epineurium

A

a thick fibrous coat that covers an entire nerve

supplied by blood and lymphatic vessels

type I collagen and fibroblasts

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39
Q

perineurium

A

dense CT, covers bundles of axons within nerve

epithelial-like fibroblasts on inner surface

blood nerve barrier

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40
Q

perineurium fibroblasts

A
  • -joined by tight junctions
  • -zonula occludens
  • -permeable barrier
  • -this layer has to rejoined in surgery to reattach a limb
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41
Q

blood nerve barrier

A

endothelial cells of vessels are also linked by tight junctions

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42
Q

endoneurium

A

thin layer of reticular CT, surrounds individual fibers and schwann cells

type III collagen

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43
Q

channels on axon

A

K channels

voltage gated Na and Ca channels

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44
Q

where are dense bodies found?

A

presynaptic membrane

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45
Q

anterograde direction

A

from cell body to distal end of axon

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46
Q

retrograde direction

A

from axon toward cell body

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47
Q

anterograde mvt

A
  1. kinesin
  2. can be slow, intermediate or fast
  3. slow - 2 systems: SCa or SCb
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48
Q

SCa system

A

anterograde transport of preassembled microtubules and neurofilaments

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49
Q

SCb system

A

anterograde transport of enzymes, actin, clathrin

50
Q

intermediate anterograde transport

A

50-100 mm per day
mitochondria and other membrane bound organelles

(slow is 1-6mm/day)

51
Q

fast anterograde transport

A

utilizes microtubule motors
400 mm/day

synaptic vesicles and neurotransmitters

52
Q

retrograde transport

A
  1. dynein
  2. carries endocytosed materials and recycled proteins
  3. 100-300 mm/day
53
Q

glial cells

A

non-neuronal cells
typically derived from embryonic neural crest tissue

support functions in pns and cns

54
Q

glial cells are capable of ______ under appropriate conditions. ex. ?

A

cell division

astrocytes
oligodendrocytes
schwann cells
microglial cells
ependymal cells
55
Q

astrocytes

A
  • -neuroepithelium
  • -only in cns
  • -numerous processes that terminate on capillaries of pia matter
  • -2 types
56
Q

types of astrocytes

A
  1. fibrous astrocytes

2. protoplasmic astrocytes

57
Q

fibrous astrocytes

A

in white matter
long processes
few branches

58
Q

protoplasmic astrocytes

A

in gray matter
short processes
many short branches

59
Q

astrocyte functions

A
  1. regulate composition of intercell matrix and entry into it
  2. structural support
  3. blood brain barrier
  4. K sink
  5. help form scar tissue in cns
60
Q

astrocyte: blood brain barrier

A

–mediate exchange of nutrients and metabolites between blood and neurons

end feet form glia limitans

61
Q

oligodendrocytes

A
  1. neuroepithelium

2. only in cns

62
Q

oligodendrocyte functions

A
  1. lie close to neuron cell bodies in gray matter
  2. function as satellite cells
  3. surround unmyelinated axons in gray matter
  4. myelinate axons in cns
63
Q

_______ are the counterparts to schwann cells in the cns.

A

oligodendrocytes

64
Q

schwann cells

A
  1. from neural crest
  2. myelinate axons in cns

each cell myelinates only a portion of a single axon

65
Q

microglial cells

A
  1. derived from bone marrow
  2. phagocytic in cns
  3. recruit leukocytes across bbb
  4. monitor immune responses (with astrocytes)
66
Q

ependymal cells

A
  1. ciliated cuboidal cells
  2. neuroepithelium
  3. line ventricular system of cns
67
Q

ependymal cell functions

A

function in transport

in choroid plexus - secrete cerebrospinal fluid

68
Q

satellite cells

A
  1. from neural crest
  2. form moons around cell bodies in ganglia
  3. function as insulators
69
Q

myelination in pns

A
  1. schwann cell plasmalemma wraps around axon

2. schwann cytoplasm is squeezed out leaving behind concentric layers of membranes

70
Q

internal and external mesaxon

A

outer and innermost points of fusion between the outer leaflets

71
Q

myelination in pns: intraperiod line

A

–electron dense line created by extracellular space between adjacent outer leaflets

72
Q

major protein zero: intraperiod line

A
  1. only in pns

2. creates homodimers

73
Q

major protein homodimers

A

homodimers form homotetramers w/ opposing outer leaflets

74
Q

in the cns, major protein zero is replaced by ?

A

a proteolipid protein

w/ 4 homophobic domains

75
Q

myelination in pns: major dense line

A
  1. e- dense line
  2. created by cytoplasmic space remnant between adjacent inner leaflets
  3. myelin basic protein
76
Q

myelin basic protein

A
  1. found in pns
  2. abundant protein associated w/ inner leaflets
  3. stabilizes leaflet
77
Q

Schmidt-lanterman clefts

A

(incisures)

1. residual areas of cytoplasm w/in major dense lines

78
Q

if you have mutations in connexon 32?

A

you will be unable to myelinate axons

79
Q

heterotypic tight junctions

A

found between the axolemma and the cytoplasmic loops adjacent to the node of ranvier

80
Q

autotypic tight junctions

A

found between processes of adjacent schwann cells and the incisures of Schmidt-lanterman

81
Q

presynaptic membrane

A
  • -v gated Ca channels
  • -SNAPs (proteins)
  • -vesicle docking proteins
  • -Synapsins
82
Q

SNAPs

A
  1. bind synaptic vesicles to the presynaptic membrane
  2. soluble NSF
  3. found in cytosol of terminal
83
Q

vesicle docking proteins

A

SNAP receptors found in presynaptic and synaptic vesicular membranes

84
Q

synapsins

A

filaments in presynaptic membrane

85
Q

postsynaptic membrane has _______ receptors

A

neurotransmitter

86
Q

list types of synapses - 6

A
  1. axosomatic
  2. axoaxonic
  3. axodendritic
  4. axospinous
  5. excitatory
  6. inhibitory
87
Q

axosomatic

A

axon terminal synapse w/ neuron cell body

88
Q

axoaxonic

A

axon terminal synapse w/ another axon

89
Q

axodendritic

A

axon terminal synapse w/ a dendrite

90
Q

axospinous

A

axon terminal synapse w/ a dendritic spine

91
Q

excitatory synapse

A

more positive end-plate potential

closer to threshold

easier for the cell to fire

92
Q

inhibitory synapse

A

more negative end-plate potential

farther from threshold

harder for the cell to fire

93
Q

meninges and spaces: superficial to deep

A
bone
epidural space
dura mater
subdural space
leptomeninx
-arachnoid memb.
--arachnoid villi
---pia mater
94
Q

the epidural space is ______ around the _____.

A

absent around brain

95
Q

dura mater

A
  1. tough thick dense fibrous CT
  2. physical protection
  3. serves as periosteum in cranium
96
Q

around the spinal cord, the dura mater .…..

A
  1. forms a CT tube that is separated from the bone of vertebrae by space (epidural space)
97
Q

within the dura mater

A
  1. endothelial lined venous sinuses
    - -receive blood from cerebral drainage
    - –cerebrospinal fluid via arachnoid villi
98
Q

dural border cells

A

separate the dura mater from the subdural space

99
Q

arachnoid

A
  1. a meninx of delicate CT
  2. outer layer faces subdural space
  3. inner side attached to pia mater by delicate strands
100
Q

outer layer of arachnoid

A
  • -faces subdural space

- -a single layer of arachnoid barrier cells

101
Q

arachnoid trabeculae

A

delicate strands of CT connecting arachnoid and pia mater

102
Q

subarachnoid space

A

space between arachnoid and pia mater

103
Q

_______ fills the subarachnoid space

A

cerebrospinal fluid

104
Q

arachnoid villi

A
  1. make up arachnoid barrier cells
  2. extend into venous sinuses of dura mater
  3. allow passage of cerebrospinal fluid
105
Q

pia mater

A
  1. thin, delicate CT
  2. lies directly on brain and spinal cord
  3. follows contour of brain and dips into sulci
  4. cannot be removed w/o damaging NT
106
Q

pia mater CT is continuous w/

A

the perivascular CT of cerebral and spinal cord blood vessels

107
Q

perivascular spaces

A

tunnels covered w/ pia mater

108
Q

choroid plexus

A
  1. a highly infolded simple cuboidal epithelium that extends into the ventricles from the roof plate
109
Q

cerebrospinal fluid barrier

A

cuboidal cells of choroid plexus are linked by tight junctions forming the barrier

110
Q

choroid plexus apical domain

A

apical microvilli
infolding basal memb.

have abundant mito to indicate active transport mechanisms

111
Q

capillaries in choroid plexus

A

the endothelial cells lack tight junctions so they are very leaky

112
Q

ependyma

A
  1. layer of simple cuboidal epithelium - that lines the ventricular walls
  2. cells linked by zonula adherens
  3. have apical modifications
  4. basal domain in contact w/ astrocytes
113
Q

glia limitans

A

basal domains of ependymal cells are in contact w/ astrocytic processes forming the glia limitans

part of bbb

114
Q

tanycytes in the 3rd ventricle are tightly linked …..

A

to adjacent ependymal cells

send processes thru glia limitans to form end-foot processes on underlying blood vessels

115
Q

types of ganglia

A

sensory (dorsal root)

autonomic

116
Q

sensory ganglia

A
  1. capsule of CT = epineurium
  2. clustered w/ pseudounipolar neurons w/in capsule
  3. postganglionic axons myelinated
117
Q

autonomic ganglia

A
  1. found in front of aorta
  2. capsule of epineurium
  3. clustered multipolar neurons
  4. postganglionic axons not myelinated
118
Q

autonomic ganglia neurons

A
  • -cluster multipolar neurons
  • -receive input from myelinated preganglionic neurons

*postganglionic axons are not myelinated

119
Q

sensory ganglia satellite cells

A
  1. similar to schwann
  2. form single layer about cell bodies of neurons
  3. apical surfaces face basal lamina not the neuron
120
Q

autonomic ganglia satellite cells

A
  1. similar to dorsal root ganglia but less numerous