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Histology Exam 1 > Nervous Tissue > Flashcards

Nervous Tissue Flashcards

1
Q

Neurons

A

Structural & functional unit of nervous system

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2
Q

what do neurons consists of and its location?

A
  • Neurons constitute most sensory receptors, conducting pathways, & integration centers
  • All neurons terminally differentiated (Go); do not divide, regeneration of axons possible
  • location: in CNS
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3
Q

2 basic cell types of nervous tissue?

A
  1. neurons

2. supporting cells (non-conducting)

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4
Q

supporting cells

A

physical support & protection, electrical insulation, metabolic exchange

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5
Q

3 categories of supporting cells

A
  1. neuroglia in CNS
  2. Schwann cells in PNS
  3. satellite cells in ganglia
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6
Q

Soma

A

cell body—contains nucleus, surrounded by perikaryon

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7
Q

perikaryon

A

cytoplasm surrounding the nucleus in the soma

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8
Q

Nissl substance

A

rER

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9
Q

Neurilemma

A

plasma membrane surrounding cell

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10
Q

melanin, lipofuscin

A

age pigment within cell body

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11
Q

Neuron characteristics

A
  1. dendrites
  2. axon
  3. cell body
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12
Q

dendrites

A

highly branched neuron processes, receive stimuli from other neurons or environment (afferent)

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13
Q

single axon

A

transmits stimuli to other neurons or effector cells (efferent)

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14
Q

axon hillock

A

axon arises from

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15
Q

terminal bouton

A

terminates in distal swelling of axon

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16
Q

axonal transport

A

Movement of products down axon

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17
Q

slow axonal transport

A

carries cytoskeletal elements

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18
Q

fast axonal transport

A

carries membrane-bound organelles

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19
Q

Anterograde transport

A

From cell body down axon, uses kinesin

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20
Q

Retrograde transport

A

From axon to cell body, uses dynein

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21
Q

What are the basic neuron types? (4)

A
  1. multi-polar neuron
  2. bipolar
  3. unipolar
  4. pseudounipolar
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22
Q

multi-polar neuron

A
  • most common
  • several dendrites
  • (e.g., motor neurons, interneurons)
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23
Q

Bipolar

A

single dendrite opposite axon (e.g., receptor neurons of retina)

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24
Q

Unipolar

A

no dendrites on soma, axon only (eg. sensory axons)

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25
Q

Pseudounipolar

A

single dendrite & axon fuse; soma off to one side (e.g., dorsal root ganglia)

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26
Q

Physiology of nervous conduction

A
  • [Na+] & [Cl-] higher outsidecell
  • [K+] higher insidecell
  • Due to Na-K pumps in neuron cell membrane, Na pumped outside cell, K inside => + charge outside, —charge inside => ~ net –80 uv resting membrane potential inside cell
  • Action potential–“all or none” response
  • Arises in cell body as a result of an afferent stimulus•Causes region of plasma membrane to depolarize
  • Voltage gated Na channels open & Na rushes into cell
  • Voltage gated K leak channels open & K rapidly leaks out of cell
  • —cell’s electrical potential neutralized (goes to zero, or slightly +) —i.e., membrane loses its polarity, or becomes “depolarized”
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27
Q

Causes reversal of resting potential

A

cell’s electrical potential neutralized (goes to zero, or slightly +) —i.e., membrane loses its polarity, or becomes “depolarized”

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28
Q

Refractory period

A
  • Na channels close & can’t reopen for 1-2 msec

- where N is unresponsive to stimuli

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29
Q

Absolute refractory period

A

where response to stimulus impossible

30
Q

Relative refractory period

A

where only a very strong stimulus can initiate depolarization

31
Q

What happens after Na channels close…?

A

voltage gated K channels also close; membrane repolarizes, ends refractory period

32
Q

“wave of depolarization”

A

Opening & closing of Na & K channels in “domino effect” along axon => change in electrical potential of membrane which travels down axon

33
Q

neurotransmitter

A

Action potential then conducted to effector cell at synapse

34
Q

Neuromuscular junctions

A

Specialized junctions between neurons or between neuron & effector cell

35
Q

Synapses

A

each synapse is unidirectional; response to a stimulus either excitatory or inhibitory

36
Q

Entrainment

A

more a pathway is used, easier it is to access

37
Q

Terminal bouton

A
  • separated from effector cell by synaptic cleft

- Contains mitochondria & membrane bound synaptic vesicles containing chemical neurotransmitters

38
Q

pre synaptic membrane

A

signaling molecules released

39
Q

post synaptic membrane

A
  • Diffuse across synaptic cleft, bind to receptor molecules

- Vesicles on post-synaptic membrane contain hydrolytic & oxidative enzymes—e.g., acetylcholinesterase; MAO

40
Q

what 2 neurotransmitters are used in PNS

A

Acetylcholine& norepinephrine (adrenaline)

41
Q

Automatic Nervous System is divided into what?

A
  1. sympathetic

2. parasympathetic

42
Q

Sympathetic

A

“fight or flight” response

•Uses noradrenaline (nor-epinephrine) as excitatory neurotransmitter (adrenergic)

43
Q

Parasympathetic

A

promotes relaxation

Uses acetylcholineas excitatory neurotransmitter (cholinergic)

44
Q

Inactivate neurotransmitters between consecutive impulses

A

prevent continuous stimulation (e.g., tetany)

45
Q

Peripheral Nervous Tissue

A
  • Contains afferent &/or efferent fibers (axons) of either somatic (voluntary) or autonomic (involuntary) Nn
  • Cell bodies located in CNS or in ganglia
46
Q

peripheral nerves

A

bundle of axons, or fascicle

47
Q

Schwann cells

A
  • provide structural & metabolic support
  • derived from neural crest associated with axons provide metabolic support & electrical insulation
  • Nuclei along length of axon belong to Schwann cells
48
Q

In PNS, all neurons enveloped by…..?

A

Schwann cells

49
Q

In non-myelinated neurons….

A

several axons lie in channels within Schwann cell, surrounded by single layer of neurilemma from Schwann cell

50
Q

Myelinated neuron

A
  • insulated by many concentric layers of plasma membrane from many Schwann cells
  • Many axons bound together in fascicle form nerve
51
Q

sheath of Schwann

A

consists mostly of cell membrane—forms myelin sheath~ axon

52
Q

nodes of raniver

A
  • Gaps in myelin sheath between adjacent Schwann cells
  • responsible for rapid “saltatory” conduction
  • Membrane depolarization occurs only at nodes
53
Q

oligodendrocytes

A
  • myelinated Nn in CNS sheathed by cells

- One oligodendrocyte surrounds several Nn with >1 layer of plasma membrane

54
Q

Rate of conduction

A

diameter of axon, myelin also increase conduction rate

55
Q

Peripheral Nervous Tissue

A

Individual axon and Schwann cells surrounded by loose connective tissue endoneurium

56
Q

perineurium

A
  • surrounds multiple axons organized into bundles (fascicles)
  • cells of perineurium unique
57
Q

what plays a role in axon regeneration

A

Exhibit epithelioid & myoid features

58
Q

epineurium

A

Larger Nn containing several fascicles surrounded by additional layer of connective tissue

59
Q

what do blood vessels tend to follow?

A

epi and perineurium

60
Q

In ANS, two neurons connect CNS to____

A

preganglionic & postganglionic neurons

61
Q

Preganglionic(= presynaptic) neurons

A
  • cell bodies in gray matter of brain & cord in CNS

- will synapse with post ganglionic

62
Q

postganglionic (= postsynaptic) neurons

A

cell bodies located in ganglia

63
Q

Ganglia

A

discrete aggregations of postsynaptic neuron cell bodies located outside the CNS

64
Q

neural crest

A

where embryologically are derived, like all peripheral neurons

65
Q

In the ganglia, each cell body (soma) are surrounded by what?

A

satellite cells

66
Q

satellite cells

A

derived from neural crest—provide structural & metabolic support

67
Q

location of gangila in sympathetic and parasympathetic

A

sympathetic ganglia: the parallel vertebral column

parasympathetic: ganglia lie in or near effector organ

68
Q

Sympathetic ganglia include what? (2)

A

include prevertebral & paravertebral ganglia

69
Q

prevertebral ganglia location

A

anterior to spine—e.g., celiac & mesenteric plexi

part of sympathetic ganglia

70
Q

paravertebral ganglia location

A

1’ in sympathetic trunk

part of sympathetic ganglia

71
Q

Parasympathetic ganglia location

A

located in or near effector organ e.g., between smooth Mm layers of gut wall—

Histology Exam 1 (10 decks)

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