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Histo Exam 1 > Nerves (weeks) > Flashcards

Nerves (weeks) Flashcards

1
Q

`What ar the features of Neuronal Cell Body (perikaryon, soma) ? In the Nucleus, nucleolus, inclusions, axon hillock , golgi, cytoskeletal elements.

A
  • Nucleus:
    • Centrally located
    • Contains active euchromatin (not always active)
  • Nucleolous: sometimes 2 or more
  • Inclusions
    • lipid, glycogen, melanin or iron
    • Lipofucsin (product of lysosomes) brown pigment , byproduct of undigested material- increases with age
  • Axon Hillock
    • Lacks Nissl substance
    • Cytoskeletal elements (microtubules, intermediate filaments, microfilaments) funnel into axon
  • Golgi
    • Can be extremely ware and well developed in neurons
  • Cytoskeletal Element
    • Neurofibrils (cluster)
    • Neurofilaments (neuron specific intermediate filaments)
      • made of 3 different intermediate filaments (70kDa, 150KDa, 200kDa)
    • Microtubules (aka neurotubules)
    • Microfilaments
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2
Q

Do cell bodies replicate?

A

No; Neurons don’t divide, they must last a lifetime however cellulary components have a normal turnover rate.

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3
Q

What are dendrites? What is its apppearance? Specifiy the branching patterns. What makes the dendrites different from the other cell parts? Function.

A
  • The number of dendrites could be either single or multiple.
    • It has a large diameter, doesn’t extend far from the cell body, ALMOST never myelinted
    • Tapered
  • Branching: acute angles, branch repeatedly, diameters vary
  • The unique difference in organelles.
    • Contents are similar to soma
    • golgi can extend into dendrites
    • contains ribosomes
    • microtubules prevalent (evenly spaced)
  • Function: receptor processes, recieving info (stimuli from other neurons or external environment,
    • graded potentials
    • receiving synapses
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4
Q

What are axons? What is its apppearance? Specifiy the branching patterns. What makes the axons different from the other cell parts?

A
  • Not all neurons have axons
  • The appear: 1-30 nm
    • small constant diameter
    • smooth contours and cylindrical shape
    • may extend long distances from the cell body (some axons in humans over 1 m long)
    • Can be myelinated
  • Branching
    • branches infrequently
    • branches obtuse angles
  • Unique differences in organelles
    • Lack Nissl bodies and golgi
    • NEVER contains ribosomes
  • Neurofilaments and microtubules prevalent (no regular arrangement)
  • Function:
    • Action potential
      • Conduction and transmission
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5
Q

What are dendritic spines?

A
  • Thay have mushroom shaped structures that are connected to the dendritic shaft.
    • SER and filamentous proteins extend into spines- no ribosomes
    • Function: increase receptive area
  • occur in the vast numbers in order of 10^14 in the human cerebral cortex
  • Size: 1-3 micrometerx long
  • increase binding site surface area (axons come and form synapsis)
  • Dynamic structures
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6
Q

What is a Biopolar neuron? What is it used for?

A
  • One dendrite, one axon
  • rare
  • special senses:
    • Cochlear (hearing)
    • Vestilandar (balance,eye movemeny
    • Retina
    • taste
    • smell
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7
Q

What is Pseudounipolar neuron?

A
  • one process close to soma
  • extends short distance, then divides in to a T
  • Stimuli are received from dendrites passed directly to Axon Terminal
    • found in sensory neurons
    • and in gnglia such as dorsal root ganglia (DRG)
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8
Q

What is Multipolar neuron?

A
  • More than 2 cellular processes
  • Most in the body are mulitpolar
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9
Q

What is a synapse (Bouton) responsible for?

A
  • Responsible for the unidirectional transmision of nerve impulses
    • converts electrical impulse into a chemical signal
  • sites of functional contact between neurons
    • other neurons
    • effector neurons
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10
Q

What are the types of synapses?

A
  • Chemical synapses (99%)
    • two types
      • without reuptake (20%)
        • Ex: Ach, achetycholesterase degrades Ach as fast as it is produced
      • with uptake (80%)
  • electrical synapses (rare)
    • found in the retina
    • do NOT require NTs
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11
Q

What happens when someone takes cocaine?

A
  1. )cocaine inhibits the reuptake of dopamine and serotonin in the pleasure center of the brain
  2. ) overtime the post synaptic receptors down regulate (not as many embedded). crash b/c not enough receptors
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12
Q

What are the morphologies and sizes of Ach, NE, inhibioty, serotonin (5HT, 5 hydroxytrptamine)?

A
  • Ach: clear in color, ~40-50 nm
  • NE: 40-60 nm range, small clark centrally located dot
  • Inhibitory: tend to be flattened out
    • (GABA;gama -amino butyric acid)
  • Serotonin, aka (80-150nm) damso dark staining core
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13
Q

What are the assigned classification of neurotransmitter?

A

Over 50 and more types of neurotransmitters.

  • GABA:most abundant neurotransmitter in CNS
  • Dopamine: associated w/ pleasure center, also found in substantia nigra and basal ganglia
  • Glutamate: most abundant excitatory neurotransmitter in CNS
  • Peptides
  • Substance P: involved in pain
  • Vasoactive intestinal polypeptide (VIP)
  • Somatostatin (GHIH)
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14
Q

What are non-directed synapses?

A

Synapes without distinct postsynaptic targets.

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15
Q

What is glia (neuroglia)?

A
  • 10/1 glia: neurons
  • provide protection and support for neurons
  • proliferation/ constant slow turnover
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16
Q

What are the 4 types of glia?

A
  1. Astrocytes
  2. Myelin producing cells
  3. Microglia
  4. Ependymal cells
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17
Q

What is te must numerous type of glia cells?

A

Astrocytes have morphological and functional diversity.

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18
Q

What are the morphological subtypes of astrocytes? What is the size of its soma? what are the common markers? What is the tumor of astrocytes called?

A
  • Fibrous (in white matter): few long processes
  • protoplasmic (in gray matter): many short processes
  • others in unique brain regions (bergmann glia, cerebellum)
  • Soma: 10-20 micrometers

The common markers: glial fibrillary acidic protein (GFAP), and glutamate synthetase

  • ​Astrocytomas: tumors arising from fibrous astrocyes; account for ~80% adult brain tumors
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19
Q

What is the function of astrocytes in metabolic and reaction to injury?

A

Metabolic:

  1. store gycogen
  2. K+ sink
  3. store neurotransmitter enzymes
  4. proccesses surround neurons (can extend 100 micrometers)
  5. have perivascular end feet that cover blood vessels

Reaction to injury:

  1. increase in size
  2. increase in number
  3. glial scar
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20
Q

What are types of myelin producing cells?

A

Olgiodendrocytes for several CNS axons

Schwan cells: Single PNS axon

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21
Q

What is the description of oligodendrocytes (CNS)?

A
  • size: 10-12 micromenters soma
  • small, dark, round nucleus
  • cytoplasm difficult to see at LM level without markers
  • Stain light-dark (EM) depending on age of oligo
  • common markers: myelin basic proteins, galactocerebroside (gal C)
  • produces myelin for several CNS axons
  • tumors: oligodendrocytomas
  • produces myelin for several CNS axons
  • A single oligo sends out multiple tongue like processes that wrap portions that wrap multiple axons.
  • Distance of oligo may be some distance from an axon it myeleniates.
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22
Q

What are Schwann Cells (PNS)?

A

It surround myelinated (one) or unmyelinated (several) PNS axons?

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23
Q

What is mylein?

A

Lipid rich cellular extrusion acts as an insulator

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24
Q

What is the role of Microglia?

A
  • assists with macrophagic action–> phaocytotic–>ingest cellular debris
  • (bone marrow region) Mesodermal origin
  • created from blood monocytes
  • realease cytokines attracting t cells
  • can act as antigen presenting cells
  • increase in size and number with disease
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25
Q

Explain morphology of Ependymal Cells.

A
  • Form the simple epithelial like lining of ventricles of brain of centeral of the spinal cord
  • cubodial/columnar epithelia
  • line ventricles/ central canal of brain
  • cilated–>facilitates movement of CSF
  • processes can extend far into the CNS
  • markers: vimentin
  • tumor: ependymona
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26
Q

What is the Central Nervous System?

A
  • Brain and spinal cord
  • contains white matter and gray matter
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27
Q

What does white matter contain?

A
  • No or few neuron cell bodies
  • Many myelinated axons
  • Glia (oligodendrocytes,astrocytes, and microglia)
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28
Q

What does gray matter contain?

A
  • Neuron cell bodies
  • network of unmyelinated axons and dendrites (neurophil)
  • glia
  • many blood vessels compared to white matter
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29
Q

What is Ganglia?

A

collection of neurons in PNS

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30
Q

What is the PNS? What are the components of PNS?

A
  • cell bodies and nerve processes outside the brain and spinal cord
  • Sympathetic ganglia, parasympathetic ganglia,
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31
Q

What is the basic funtional unit of the reflex arc?

A
  • Afferent (input): coming in to the brain of spinal cord
  • Synapse
  • Efferent (output): sending out from CNS to PNS
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32
Q

What are the 2 types of ganglia?

A

Sensory and autonomic

33
Q

Where can sensory ganglia be found?

A
  • Cranial: cranial nerves
  • Spinal–> aka DRG
  • Sensory ganglia (peripheral nervous system)
    *
34
Q

What are the two types of motor ganglia (autonomic)? Describe the features of each type.

A
  • Sympathertic–> Not found in cranium
    • CT capsule
    • Non-distinct fiber tracts (unmyelinated) as seen at the LM level
    • cells distributed throughout
    • satellite cells
      • Scattered
      • non-uniform
    • multipolar neurons
      • Eccentric Nucleus
      • Multiple processes
  • Parasymphatethic-​
    • 2-3 or 100 neurons
    • located near organ of innervation–> often located in the wall of organ innervated
    • capsule may be indistinct
    • usually fewer neurons than in symphathetic ganglia
    • otherwise similar to sympathetic ganglia
35
Q

What type of cells lines the ventricles?

A

epidymal cells

36
Q

What produces the cerebral spinal fluid? Where does CSF circulate?

A

Choroid Plexus

It circulates through the ventricles, central canal, the subarchnoid space and perivascular space.

37
Q

What is meningitis and what the cause associated with?

A

Infflammation of the meniges (usually pia and subarchoid)

38
Q

What is the structural continuity of the connective tisse covering of the peripheral nerves/ ganglia?

A
  • Dura- epineurium –> fibrous coat of dense CT, rich in nerve endings
  • arachnoid- perineurium–> flatted epithelial-like cells
  • subarachoid space- sub perineurial space
  • pia: endoneurium; thin layer of reticular fibers-> produced by schwann cells
39
Q

What are the characteristics of ependymal cells?

A
  • Cubodial/ columnar epithelia
  • line ventricles/ central canal
  • cilated–> help circulate CSF
  • processes can extend far into the CNS
  • possess microvilli
40
Q

What are the characteristics of choroid plexus?

A
  • modified ependyma and blood vessels extend into the ventricles
    • located in each ventricle
    • secretes CSF
    • endothelium
    • contains choroid cell
    • made up of dilated penestrate capillaries enveloped invaginated folds of pia matter.
41
Q

What is the function of Olgiodendrocytes?

A

produces myelin for several CNS axons

42
Q

In PNS all axons (myelinated and unmyelinater are surrounded by what?

A

Schwann cells

43
Q

Unmyelinated nerve has no nodes of ranvier. T or F?

A

T

44
Q

How many axons does schan cover in mylinated?

A

One axon. Multiple schwanns over entire length.

45
Q

How many axons does unmyelinated schwann cover?

A

multiple axons

46
Q

In the CNS, myelinated axons are surrounded by what type of cells? Up to how many axons can it myelinate?

A

Oligodendrocytes

1 olgiodndrocyte can myelinate several (5-10) axons

47
Q

What are the characteristics of unmyelinated axons?

A
  • contain either no myelin sheath or surrounded by astrocytes
48
Q

What is the function of astrocytes?

A
  • Invests all neurons
  • support, both physical and metabolic
  • end feet regulate transport
  • forms pia-glial barrier
  • help control ionic an chemical enviornment of neurons
  • store glycogen
  • have role in synaptic activity
  • help confine NT’s to synaptic clefts
  • remove excess NT’s by phagocytosis
49
Q

What is another structure and function of astrocytes in the anatomical blood brain barrier?

A
  • created by endothelial cells linked by zonula occludens
  • has basement membrane
  • surrounded by astrocyte end feet
  • passagage across is severly restricted.
  • substance that cross well after certain lipid soluble molecules (02, CO2, EtOH)
  • Macromolecules are transported by specific receptor mediated endocytosis
  • help control ionic and chemical enviornment in neurons.
50
Q

What are the types of axoplasmid transport (movement of material in the neuron)?

A
  1. ) anterograde transport
  2. ) retrograde transport
51
Q

What is anterograde transport?

A

It carries material away from cell body

  • fast (20-400mm/day)
    • moves organelles (mitochondria,vesicles)
    • moves molecules (neurotransmitters)
  • Slow (.6-4mm/day)
    • moves cytoskeletal componenets (tubilin, actin)
    • moves axolemma components
52
Q

What is retrograde transport ?

A

(carries material toward cell body)

  • dyenein used
  • fast-there is no slow retrograde transport
  • pathway followed by toxins of viruses that enter CNS nerve endings
  • material take up endocytosis
53
Q

Describe regeneration for mammalian neurons.

A
  • mammaalian neurons don’t typically divide
  • degeneration usually represent permanant lose
  • neuronal proccesses in CNS have narrow limits on sympathetic activity after injury
  • glial scaring limit agent
  • peripheral nerves can regenerate if their cell bodies aren’t destroyed
54
Q

What happens at proximal to lesion of Neurons?

A
  • primary degeneration
  • chromatolysis
55
Q

What is chromatolysis?

A
  • cellualredema and loss of nissl substance form cell body in primary lesion
56
Q

What happens when the lesion is distal of neurons?

A

secondary degeneration (wallerian); anterograde degeneration

axon degeneration

57
Q

What is Nissl Substance made of?

A

Contains Nissl Substance (RER and free ribosomes;alternating pattern)

58
Q

What does the axon hillock lack? what is it used to differentiate from?

A

It lacks nissl substance and golgi. its used to differentiate from the axon from dendrites

59
Q

what are neurofibrils?

A

Cluster of neurofilaments

60
Q

All neurons have axons. True or false?

A

False

61
Q

What is pia analogous to? what is it made of? what is it made by?

A

Endoneurium, thin reticular fibers, produced by schwann cells.

62
Q

What is the chloroid plexus?

A

Modified ependyma and blood vessels extend into ventricles.

63
Q

Where is CSF circulated?

A

Through ventricles, central canal, subarachoid space and perivascular space.

64
Q

What type of areas does astrocytes cover?

A

Astrocytes provide a covering for the bear areas of mylein axons (nodes of ranvier and synapses)

65
Q

What are the characteristics of microglia?

A
  • markers: MAC-1, MAC-3, OX42
  • 10 micrometers soma
  • usually found near blood vessels
66
Q

What is the main function of microglia?

A

Function: monitor CSF

  • line ventricles/ central canal of brain
67
Q

What is the function of ependymal cells?

A

funtion monitor and modify CSF content

68
Q

all axons both myelinated and unmyelinated in the PNS are surrounded by what cell?

A

schwann cell

69
Q

All unmyelinated axons in the CNS are surrounded by what type of cells?

A

Astrocytes

70
Q

Which cell helps confine NTs to synaptic clefts and remove excess NTs by phagocytosis?

A

astrocytes

71
Q

What main microtuble protein is used for anterograde?

A

Kinesin

tubulin and acting for cytoskeletal movement

72
Q

What main microtuble protein is used for retrograde?

A

Dynenin

73
Q

What is the limiting agent of symphathetic activity after injury?

A

Glial scarring

74
Q

Where are electrical synapses found? and what don’t they require?

A

Found in retina

don’t require NTs

75
Q

What is the most abundant NT in CNS? What is the most abundant excitatory in CNS?

A

GABA, Glutamate

76
Q

other than the exception microglia, where do all the other glia originated from?

A

Ectroderm (nerual tube)

77
Q

Which neurotransmitter are mainly used in the parasymphatetic and symphatetic?

A

Parasymphatetic: Ach

symphathetic: NE

78
Q

What are astrocytes roles in synaptic activity?

A

Help confine NTs to synaptic clefts. remove excess NTs by phagocytosis.

Histo Exam 1 (16 decks)

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