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Neurology > Neurones And Glia > Flashcards

Neurones And Glia Flashcards

1
Q

What do glia do?

A

Support, nourish and insulate neurones

Remove waste

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2
Q

Name the types of glia

A

Astrocytes
Oligodendrocytes
Microglia

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3
Q

Which is the most abundant those of glia cell

A

Astrocytes

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4
Q

Functions of astrocytes?

A

Structural support
Provide nutrition for neurones via glucose-lactose shuttle
Remove neurotransmitters
Maintain ionic environment by buffering K+
Form part of blood brain barrier

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4
Q

How is the supply of glucose to neurones supplemented?

A

Astrocytes produce lactate which is transferred to neurones via the glucose-lactate shuttle (because neurones cannot store or produce glycogen)

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5
Q

Describe how the glucose lactate shuttle works

A

Glucose taken into the astrocyte from the bloodstream via GLUT1

Glucose -> glycogen -> pyruvate -> lactate

Lactate transported to interstitial pace via MTC1 along with H+

Transported into the neurone via MCT2 along with H+ where it is metabolised

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6
Q

When is the glucose-lactate shuttle used?

A

When there is high demand/very active - only supplies glucose for about 5 mins

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7
Q

How do astrocytes remove neurotransmitters?

A

Have transporters for transmitters to keep the extracellular concentration low

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8
Q

Why do astrocytes need to buffer potassium and how?

A

Potassium is released into the extracellular space by neurones and can cause depolarisation of a neurone if it builds up

Taken up by astrocytes via
🔹Na-K-ATPase
🔹Na-K-2Cl
🔹Potassium channels

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9
Q

What is oligodendrocytes do?

A

Myelinate axons in the CNS - the equivalent of Schwann cells in the PNS

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10
Q

What is the role of microglia?

A

Immunocompetent cells

  • recognise foreign material and are activated
  • dendritic processes swell so they can phagocytose foreign material
  • brain’s main defence system
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11
Q

Which embryonic tissue is the CNS derived from?

A

Endoderm

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12
Q

Which embryonic tissue are microglia derived from?

A

Mesoderm

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13
Q

Functions of the blood brain barrier?

A

Limit diffusion of substances from the blood to the extracellular fluid
Maintain the correct environment for neurones

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14
Q

What makes up the blood brain barrier?

A

Tight junctions between endothelial cells of capillaries

Basement membrane surrounding the capillary

Foot processes of astrocytes

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15
Q

What are some substances that can be transported across the blood brain barrier?

A

Glucose
Amino acids
Potassium

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16
Q

Which molecules can diffuse freely across the blood brain barrier?

A

Gaseous molecules and water

Lipophilic molecules

17
Q

What is meant by saying the CNS is immune privileged?

A

Has a specialised immune function

T-cells can enter the CNS but their inflammatory response is limited

Any inflammatory expansion in the CNS would not be tolerated due to rigidity of the skull

18
Q

What is the axonal hillock?

A

Where the action potential is generated to pass along the axon

Connects the cell body to the axon

19
Q

Name the different categories and types of neurotransmitters

A

Amino acids

  • glutamate
  • GABA
  • glycine

Biogenic amines

  • NA
  • dopamine
  • serotonin
  • histamine
  • ACh

Peptides

  • dyphorin
  • enkephalins
  • substance P
  • somatostatin
  • CCK
  • neuropeptide P
20
Q

Which are the main neurotransmitters to cause an excitatory response?

A

The amino acids - glutamate

21
Q

What are the two main types of glutamate receptors?

A

Inonotrophic - integral ion channel which increases the Na and K permeability, and sometimes Ca

Metabotrophic - a GPCR which allows changes in IP3 or (decreased) cAMP levels

22
Q

What are the main ionotrophic receptors and what do they do?

A

AMPA: increase Na and K permeability

NMDA: increase Na, K and Ca permeability

Kainate receptors

23
Q

What does it mean if a receptor is excitatory?

A

Will cause depolarisation and subsequently allow more action potentials to fire
(Excitatory Post-Synaptic Potential - EPSP)

24
Q

How are glutamate receptors thought to have memory?

A

Activation of NMDA and mGluRs can lead to upregulation of AMPA receptors

25
Q

How can excessive amounts of glutamate cause cell death?

A

Can get too much entry of calcium due to activation of NMDA receptors so that intracellular concentration of calcium becomes too high

26
Q

Which are the two main inhibitory neurotransmitters and where do they act?

A

GABA in the brain

Glycine in the brainstem and spinal cord

27
Q

How do GABA(A) and glycine receptors inhibit action potentials?

A

They are integral Cl ion channels

Opening of the channels results in hyperpolarisation and this results in decreased action potential firing

(Inhibitory Post-Synaptic Potential - IPSP)

28
Q

Which drugs bind to GABA receptors and what is their effect?

A

Barbiturates
Benzodiazepines
Cause sedation and anti-anxiety

29
Q

Which neurotransmitters act as neuromodulators?

A

Biogenic amines and ACh

Regulate a diverse population of neurones

30
Q

What is the role of ACh in the CNS?

A

Acts as an excitatory neurone on nicotinic and muscarinic receptors
On receptors present on pre-synaptic terminals to enhance the release of other neurotransmitters

31
Q

What is the effect of ACh in the brain?

A

Arousal
Memory
Learning
Motor control

32
Q

What is the degeneration of cholinergic neurones associated with?

A

In the nucleus basalis of Meynert - Alzheimer’s disease

33
Q

What is the distribution of cholinergic neurones?

A

Distributed widely through the CNS
Originate in the basal forebrain and brainstem
Have diffuse projections to many parts of the cortex and hippocampus

34
Q

What functions are dopamine receptors involved in?

A

Motor control
Mood
Arousal
Reward

35
Q

Where are noradrenaline receptors found?

A

On post-ganglionic effectors synapses in the SNS

In the CNS - operate as a GPCR in the cortex, hypothalamus, amygdala and cerebellum

36
Q

What increases the release of noradrenaline and dopamine?

A

Amphetamines

37
Q

What is a decrease in noradrenaline associated with?

A

Depression

38
Q

What are peptide neurotransmitters often involved in?

A

Pain regulation

39
Q

What are the three dopamine pathways in the brain and what are they involved in?

A

Nigrostriatal: motor control

Mesocortical and mesolimbic: mood, arousal and reward

40
Q

What is the pathway/projection of noradrenergic neurones in the brain?

A

Cell bodies of noradrenaline-containing neurones located in the brainstem (pons and medulla)

Diffuse release of NA thoughout the cortex, hypothalamus, amygdala and cerebellum

Neurology (20 decks)

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