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Neuroscience and Mental Health > Neurons and Astrocytes > Flashcards

Neurons and Astrocytes Flashcards

1
Q

Difference between PNS and CNS neurons

A

Peripheral neurons (PNS): cell bodies outside brain/spinal cord

Central neurons (CNS): cell bodies inside brain/spinal cord

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2
Q

Describe events of AP generation

A
  • Na/K pump maintain RMP (-70)
  • Ligand gated Na channel open
  • Na influx -> depolarisation (>55)
  • Fast Na channel open, slow K channel open
  • depolarisation
  • Na close as K open (K efflux)
  • RMP, K channel slow to close (hyperpol + refractory period)
  • Na/K pump restores RMP
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3
Q

Name 2 main compartments in neurons (that must be kept separate)

A

Axonal compartment and somato-dendritic compartment

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4
Q

E.g. of somato-dendritic specific component?

A

Microtubule Stabilising Protein: MAP2B

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5
Q

Main advantages of a neuron having dendrites?

A

Greatly increased surface area

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6
Q

How to distinguish between axons and dendrites?

A

Axons have no spines

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7
Q

Primary dendrites VS secondary dendrites?

A

Primary dendrites branch directly off soma, whilst secondary dendrites branch off other dendrites

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8
Q

E.g. of axon specific component?

A
  • neurofilaments (for strength)
  • MTs (microtubules)
  • tau (to stabilise MTs)
  • cell-adhesion molecules (L1-NgCAM, TAG-1)
  • NTs, SNARE complexes, growth factor receptors…etc
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9
Q

Why do axons have large numbers of mitochondria?

A

To maintain membrane potential

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10
Q

Types of synapses (not boutons & varicosities)

A
  • w/ another neuron
  • neuromuscular
  • neuroglandular
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11
Q

Features of synapses (to aid function)

A
  • enriched w/ VGCCs (calcium channels)
  • abundant mitochondria
  • synaptic vesicles
  • “active zone” (aids vesicle association w/ membrane)
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12
Q

Where on an axon, is the axon potential generated?

A

Axon hillock

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13
Q

General function of synapses

axo-dendritic:
axo-somatic:
axo-axonic:

A

General function of synapses

axo-dendritic: excitatory
axo-somatic: inhibitory/modulatory
axo-axonic: inhibitory/modulatory

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14
Q

Main components of astrocytic cytoskeleton?

A
  • GFAP (glial fibrillary acidic protein)]- important
  • microtubules
  • actin
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15
Q

Unique features of astrocytes

A
  • cytoskeleton has particular proteins (GFAP)
  • express vimentin
  • glycogen granules
  • large nucleus
  • light cytoplasm
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16
Q

Examples of structures that astrocytes interact with

A
  • capillary endothelial cells
  • neuronal cell bodies
  • initial segment
  • axon
  • dendrites
  • synapses
  • ependymal cells
  • pial surface of brain
17
Q

Types of astrocytes

A
  • fibrous (long processes)

- protoplasmic (short processes)

18
Q

Where are astrocytes located?

A
  • Grey matter: protoplasmic, close to neurons]- low GFAP
  • White matter: fibrous, alongside neurons]- high GFAP
  • Cerebellum
  • SVZ]- high GFAP
19
Q

Functions of astrocytes?

A
  • modulate synaptic function: synaptogenesis (recycles glutamate) and synaptic pruning
  • produces cholesterol
  • maintain BBB (end feet wrap around endothelial cells)
  • regulate blood flow
  • neuroprotective (releases growth factors)
  • recycles NTs
  • produces anti-inflammatory cytokines
20
Q

Types of astrocytic dysfunction, leading to neurotoxicity

A
  • increased glutamate toxicity
  • increased Ca and ATP release
  • increased nitric oxide production
  • accumulation of superoxide dismutase
  • glial scar formation (e.g. around amyloid plaques)
21
Q

“States” of astrocytes?

A

A1: bad, reactive
A2: good

22
Q

Astrocyte role in the BBB?

A

Astrocytic end feet wrap around endothelial cells, providing gateway for nutrients and removal of metabolites for CNS

23
Q

Main feature of astrocytic end feet

A

Contain aquaporin 4

24
Q

Role of AQP4?

A
  • regulating extracellular space volume
  • potassium buffering
  • CSF circulation
  • interstitial fluid absorption
  • metabolic waste (e.g. amyloid) clearance
  • neuroinflammation
  • osmosensation
  • cell migration
  • Ca2+ signalling
25
Q

What is synaptic pruning?

A

Phagocytosis of unused synapses

26
Q

Mechanisms of astrocytic NT recycling?

A

Astrocytic processes surrounding synapse endocytose unbound GABA/glutamate

GABA -> glutamate

Glutamate -> glutamine

Glutamine is resupplied to neuron

27
Q

Describe mechanism of “spatial buffering” of potassium

A

Astrocytes act as potassium reservoir
[kept away from extracellular space until needed]

Extracell potassium must be low to allow neuronal function

After intense neuronal activity, potassium conc. can be very high

Astrocytes redistribute potassium to other regions through astrocytic network and gap junctions = spatial buffering

28
Q

Describe metabolic functions of astrocytes

A
  • produce lactate from glycogen: energy for neurons
  • produce cholesterol: brain is most cholesterol-rich organ and relies on this
  • Apolipoprotein E
29
Q

Describe structural role of astrocytes

A

In radial glia:

Span cortex radially from inner->outer layers
This is important for neuronal migration

e.g. Bergmann glia (cerebellum) and Muller cells (retina)

30
Q

Describe astrocytic role regarding neural stem cells

A

Radial glia can give rise to neurons, astrocytes and ependymal cells- multipotential

Mature astrocytes seem to have capacity to form neurons

Neuroscience and Mental Health (65 decks)

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