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4 Neurology > 3 Neurones and Glia > Flashcards

3 Neurones and Glia Flashcards

1
Q

What are the functions of glia? (CNS)

A

Support, nourish and insulate neurones and remove waste

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2
Q

Give some different types of glia. (CNS)

A
  • Astrocytes
  • Oligodendrocytes
  • Microglia
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3
Q

What are the functions of astrocytes? (5)

A
  1. Structural support
  2. Provide some nutrition for neurones (glucose-lactate shuttle)
  3. Remove neurotransmitters (uptake) (esp glutamate)
  4. Maintain ionic environment (K+ buffering)
  5. Help form blood brain barrier
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4
Q

Explain how astrocytes help to provide energy for neurones. (neurones do not store or produce glycogen)

A

Supplements their supply of glucose- when neurones very active

  1. Astrocytes produce lactate
  2. Lactate transferred to neurones

Glucose lactate shuttle

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5
Q

What is excitotoxicity?

A
  • pathological process
  • neurons are damaged and killed
  • due to overactivations of receptors for the excitatory neurotransmitter glutamate (too much glutamate)
    • eg NMDA receptor and AMPA receptor

Too much Ca2+ entry through NMDA receptors

Too much glutamate= excitotoxicity

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6
Q

How do astrocytes help to remove neurotransmitters?

A

Astrocytes have transporters for transmitters eg glutamate

Helps to keep extracellular conc low

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7
Q

Why is it important that the astrocytes buffer K+ in the brain ECF.

A

High level of neuronal activity can lead to rise in K+ in brain ECF

Astrocytes take up K+ to prevent this

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8
Q

What is the function of oligodendrocytes?

A

Myelinating axons in CNS

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9
Q

What is the function of microglial cells and how do they carry out this function?

A

Immunocompentent cells- brains main defence system

  1. Activated- recognise foreign material
  2. Phagocytose- remove debris and foreign material
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10
Q

What is the role of the blood brain barrier?

A

Limits diffusion of substances from blood to brain ECF

–> maintain correct environment for neurones

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11
Q

What structures form the blood brain barrier? (3)

Ie what structures can be found on end of brain capillaries

A
  1. Tight junctions between endothelial cells
  2. Basement membrane surrounding capillary
  3. End feet of astrocyte processes
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12
Q

Give some examples of substances that can be transported across the blood brain barrier (ie can’t readily diffuse).

A
  • Glucose
  • Amino acids
  • Potassium
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13
Q

How does the immune response of the brain (CNS) differ from the rest of the body (‘immune privilage’)? (4)

A
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14
Q

Fill in the missing labels:

A
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15
Q

The neurotransmitters in the CNS can be divded into 3 chemical classes. What are these 3 chemical classes and give an example of a neurotransmitter in each.

A
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16
Q

What is the main excitatory amino acid and what is the main inhibitory amino acid and where do they act??

A

Excitatory:

  • glutamate

Inhibitory:

  • GABA
  • Glycine
17
Q

What are the 2 types of glutamate receptors? Differentiate between them.

A
  1. Ionotropic
  2. Metabotropic
18
Q

How do fast excitatory responses occur?

A
  1. Excitatory transmitters-
  2. -cause depolarisation-
  3. -act on ligand gated ion channels
19
Q

Explain glutamate receptors role in learning and memory. (ie how receptors work)

A
  • NMDA receptors (and mGluRs) activated
    • Up-regulate AMPA receptors
    • Calcium entry through NMDA receptors ​
      • ​Strong high frequency stimulation- Long Term Potentiation (LTP)
20
Q

How do GABA and glycine receptors decrease action potential firing?

A
  • Integrated Cl- channels
  • Hyperpolarisation
  • IPSP- inhibitory post-synaptic potential
21
Q

Name 2 drugs that work to enhance the response of GABA and what are they used to treat? (bind to GABAA receptors)

A
  • Barbituates
    • Antiepileptic drug
      • Anxiolytic and sedative effects
        • risk of fatal overdose & dependence and tolerance
  • Benzodiazepines
    • Anxiety, insominia and epilepsy
      • Sedative and anxiolytic effects
22
Q

Name the 4 main neurotransmitters that act as modulators in the CNS. ( Biogenic amines)

A
  1. Acetylcholine
  2. Dopamine
  3. Seratonin (5-HT)
  4. Noradrenaline
23
Q

Acetylcholine is important as a neurotransmitter in the PNS. Outline its role in the PNS.

A
24
Q

Cholinergic neurones are the first to die off in Alzheimer’s disease (in nucleus basalis) . What treatment is used to help this (alleviate symptoms)?

A

Cholinesterase inhibitors

25
Q

What functions are cholinergic pathways of the CNS involved in? (3)

A
  1. Arousal
  2. Learning and memory
  3. Motor control
26
Q

Outline the cholinergic pathways in the CNS.

A
27
Q

Fill in the missing labels for the dopaminergic pathways in the CNS.

A
28
Q

Identify 2 conditions which are associated with dopamine dysfunction.

A
  • Parkinson’s disease
    • loss of dopaminergic neurones
    • substantia nigra input to corpus striatum
      • Levodopa- drug used to treat
  • Schizophrenia
    • release of too much dopamine?
      • Antipsychotic drugs= antagonists at dopamine D2 receptors
29
Q

How do the receptors to noradrenaline in the brain compare to those in the PNS?

A

They are the same (alpha and beta adrenoreceptors)- G protein-coupled adrenoreceptors

30
Q

Outline the noradrenergic pathways in the CNS.

A
31
Q

What are the functions of the serotonergic pathways in the CNS?

A
  • Sleep/wakefulness
  • Mood
32
Q

What are SSRIs used to treat? (selective seratonin reuptake inhibitors)

A

Depression and anxiety disorders

33
Q

Explain how amphetamines increase wakefullness (with relation to noradrenaline).

A

Most noradrenaline in brain comes from locus ceruleus

Locus ceruleus= inactive during sleep

Locus ceruleus- activity increases during behavioural arousal

Amphetamines increase release of noradrenaline and dopamine from locus cereuleus

(depression may be associated with deficiency in noradrenaline)

4 Neurology (22 decks)

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