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BMS11004 > BMS11004 WEEK 1 - WEDNESDAY, THURSDAY > Flashcards

BMS11004 WEEK 1 - WEDNESDAY, THURSDAY Flashcards

neurons structural components and function, methods of visualising neurons, neuronal classification, glial cells, myelins

1
Q

outline main role of neurons

A

excitable cells conducting impulses, to integrate and relay info within neural circuit

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2
Q

outline main role of glial cells

A

supporting cells, surround neurons, glue, maintain homeostasis, protection, assist neural function

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3
Q

explain what neural circuits are

A

join together to form neural systems
made up of neurons and glial cells

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4
Q

what does nissel staining show

A

distinguish between neurons and glia, stains cell nucleuolus. darker circles are glial cell nucleolus, dark circles with surrounding purple are neurons
bind to negative charge (so bind to RNA) so only stain soma
neuron has nissl bodies allowing visualisation of variation in size, density and distribution

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5
Q

name the 4 main compartments of a neuron

A
  1. soma/perikaryon
  2. dendrites
  3. axon
  4. presynaptic terminal
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6
Q

what does golgi (camillo) stain do

A

small % silver chromate to show soma, processes
doesn’t show all neurons - unknown why
Cajal used this to map out parts of brains and neurons

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7
Q

name 3 components of cytoskeleton

A

microtubules, microfilaments, neurofilaments

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8
Q

what are microtubules

A

longitudinally down neurites, hollow tube composed of polymers of tubulin

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9
Q

what is axon hillock

A

thick lump bit at top of axon

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10
Q

what is role of axons initial segment

A

important specialised area in generation of AP

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11
Q

what are axon collaterals

A

branches off main bit of axon (often at right angle), targets other neurons

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12
Q

what do axons with “many levels” have

A

high levels of divergence of signals - wider spread of signals, instead of just relay between 2

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13
Q

do axons have ribosomes

A

no rough ER (no ribosomes, no RNA so wont show on nissel stain)

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14
Q

give the length and diameter of axons

A

length: <1mm to >1m
diameter: 1um-25um

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15
Q

what is immunohistochemistry relating to axons

A

using antibodies (proteins specific to proteins) which may recognise sodium channel, then secondary antibody specific to primary antibody, with fluroescent secondary antibodies “tags”
very high v/gated Na+ channel density in axon initial segment as needed to activate AP

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16
Q

give key features of presynaptic terminals

A

no microtubules, vesicles, many mitochondria, specialised receptor proteins on membrane, often branching to allow signal amplifications

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17
Q

outline boutons en passent

A

“buttons in passing”, terminals placed along an axon

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18
Q

what is axoplasmic transport

A

movement of material down axon, as cytoplasm of axon doesn’t have ribosomes so axon proteins need to be synthesised in soma and shipped down axon

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19
Q

what is fast axoplasmic transport for and how far do they move

A

radioactive amino acids, 1000mm per day

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20
Q

what is anterograde axoplasmic transport

A

move from soma to terminal
vesicles have proteins, eg: kinesin bound to them and use ATP to help them ‘walk’ microtubule down to temrinals

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21
Q

what is retrograde axoplasmic transport

A

move from terminal to soma, eg: by dyenin
can be manipulated to study brain connection
inject tracer into muscle, taken up by presyn terminals and move back via dyein to soma. take samples and see where tracers are to find soma

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22
Q

outline dendritic arbour

A

dendritic trees made from dendritic branches, allowing signal convergence (gathering signals from different axons and integrating to send to soma)

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23
Q

give roles of dendritic spines, what happens with abnormalities or if not being used

A

isolate chemical reactions, plasticity, abnormalities can cause cognitive impairment, if less activity coming from synaptic terminal then dendritic spine lost

24
Q

name a nissl stain, and what it stains

A

cresyl violet
neurons, glia and cytoarchitecture

25
Q

what can electron microscopes study

A

synapses and organelles

26
Q

name 4 methods of structural neuronal classification

A

number of neurites
dendritic geometry
connection/projection
axon length

27
Q

give 2 methods of classifying neurons by gene expression

A

underlying structural differences
defines NT expression: inhibitory/excitatory

28
Q

neuronal classification: name 3 categories by neurites number

A

unipolar, bipolar, multipolar

29
Q

neuronal classification: explain unipolar

A

peripheral process is part axon too, small area for receiving inputs, reliable info relays
includes pseudounipolar

30
Q

neuronal classification: what is pseudounipolar

A

eg: dorsal root ganglion, 1 neurite out of some that splits and has peripherally projecting and central projections. when sensing stimuli, peripheral sends info straight from peripheral to central

31
Q

neuronal classification: outline bipolar

A

one dendrite come off one side, axon off other. only has small dendritic area at end so less area for receiving synaptic input (but highly specialised function), reliable relay of info eg: retinal bipolar cells

32
Q

neuronal classification: outline multipolar

A

still only one axon
can branch or have collaterals, but has dendrites coming off all sides of soma, with dendritic arbour
receives around 150,000 contacts

high level of convergence
most of brains neurons
eg: cerebellar purkinje cell

33
Q

dendritic geometry classifications- explain stellate cell

A

star shaped dendritic arbours

34
Q

dendritic geometry classifications- explain pyramidal cells

A

distinct atypical (long process coming off soma, splitting into tree) and basal (coming off around soma) dendritic trees
pyramidial shaped soma
allow integration of info

35
Q

explain what classification by neuron projections mean

A

classify neurons depending on whereabouts they project (sensory, motor, interneurons)

36
Q

neuronal projections classification- explain sensory

A

SNS- afferent carry sensory signal to CNS, efferent carry motor from CNS to skeletal muscle
ANS- afferent carry sensory signal from internal organ to CNS, efferent carry motor from CNS to internal organ

37
Q

outline what sympathetic efferent nerves are, where do they project from/to

A

autonomic motor nerves, project from CNS in lumar and thoracic spinal cord region

38
Q

outline what parasympathetic efferent nerves are/do

A

autonomic motor nerve, project from brain and sacral region of spinal cord

39
Q

explain afferent+efferent

A

afferent = toward CNS
efferent = away from CNS

40
Q

outline what interneurons are

A

largest class, dont leave CNS, integrate neural activity in brain structure, stay in structure alongside soma
IN COMPARISON, to: relay/projection neurons connect brain regions, axons leaving soma area to go somewhere else in the nervous system

41
Q

explain knock-out gene-expression

A

manipulating neurons to genetically fluoress specific colour based on their gene expression
use genetics for mapping projections
eg: using GFP

42
Q

name 3 cell body shape classifications

A

ovoid
fusiform
triangular

43
Q

what are golgi type 1/2

A

golgi type 1 = long axon
golgi type 2 = short axon

44
Q

what are glia

A

fills in space around neurons, can proliferate during life

45
Q

name glial cells involved in homeostasis, for CNS, PNS and ENS

A

CNS = astrocytes
PNS = satellite cells
ENS = enteric cells

46
Q

what is ENS

A

enteric nervous system, around gut

47
Q

what glial cells are myelinating cells in CNS and PNS

A

CNS = oligodendrocytes
PNS = schwann cells

48
Q

what glial cells are phagocytic in CNS and PNS

A

CNS = microglia
PNS = schwann cells and macrophages

49
Q

outline role of astrocytes

A

regulate chemical content of extracellular space (maintain ion level, pick up excess NT, actively remove NT via specialised proteins in membranes)
buffer extracellular potassium
forms BBB
neurovascular coupling to change blood supply to neuron
fence in neurons, cuff around NoR, ensheathe synapse and dendrite

50
Q

outline structure of astrocytes

A

tripartite synapse
NT receptors which trigger electrical/biochem events within cell
spatial domains
unique GFAP markers for immunohisochemistry (allowing neurons to be identified, green tag)

51
Q

what is role of astrocytes in glycogen/glucose involvement

A

when not enough glucose an astrocyte act as glycogen store, breakdown glycogen to ATP for 5-10min supply
needed for fuelling ion movement, walking kinesin along microtubule
metabolise glycogen and supply lactate
have processes surrounding blood vessels to take up glucose and convert to glycogen if needed

52
Q

explain role of microglia

A

macrophages of CNS, phagocytosis, tissue survelliance, when in inactive form can sense apoptois and become activated, then phagocytic
allows BBB- immunologically privileged site

53
Q

outline structure of microglia

A

small rod shaped soma, with many extending symmetrical processes to search for infection

54
Q

what is a current research focus on microglia

A

potential harmful role for neurodegenerative disease, roles in cell death regulations

55
Q

outline function of oligodendrocytes

A

form CNS axon myelin sheath

56
Q

outline structure of oligodendrocytes

A

single sheet of ODC membranes wraps around 40-50 axon
can have 15-30 priocesses extending from soma

57
Q

outline role of schwann cells

A

form PNS myelin sheath via oligo cytoplasms wrap multiple time around axon and cytoplasm being squeezed out of layers via compaction
maintains contact with glial cells for nourishment
guide axonal regeneration post damage (why only occur in PNS)

BMS11004 (29 decks)

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