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2.4.1. Nervous System > The Role of Neurones and Glia > Flashcards

The Role of Neurones and Glia Flashcards

1
Q

An important source of dopamine for the motor system can be found in which structure?

A

Substantia nigra

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2
Q

Which cell type can assume a macrophage-like appearance when activated?

A

Microglia

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3
Q

Which cell type is primarily responsible for maintenance of the BBB?

A

Astrocytes

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4
Q

What are the peripheral side effects of L-DOPA?

A

Tend to be GI related

  • nausea
  • anorexia
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5
Q

How are the side effects of L-DOPA ameliorated by giving carbidopa?

A

1) L-DOPA to dopamine by AADC (aromatic amino acid decarboxylase)
2) increased dopamine = GI side effects
3) carbidopa inhibits AADC = decreased side effects

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6
Q

What is the somatic nervous system?

A

Part of the peripheral NS

Responsible for voluntary muscle and reflex arc

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7
Q

What is the autonomic nervous system?

A

Parasympathetic and sympathetic NS

Controls bodily functions not consciously directed

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8
Q

What structures are in the peripheral NS?

A

Dorsal and ventral roots

Spinal nerves

Peripheral nerves

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9
Q

What structures are in the central NS?

A

Cerebral hemispheres

Brainstem and cerebellum

Spinal cord

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10
Q

Describe the blood supply of the brain

A

Anterior, middle and posterior cerebral arteries

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11
Q

Describe the cranial meninges

A

Dura mater - tough fibrous layer, adhered to bone (periosteal, meningeal)

Arachnoid layer - CSF present in subarachnoid space

Pia mater

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12
Q

What types of glia cells exist in the nervous system?

A

Astrocytes

Oligodendrocytes

Microglia

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13
Q

Astrocytes

A

Most abundant glial cell

Structural support

Provide nutrition for neurones = glucose-lactate shuttle

Remove excess neurotransmitters = important for glutamate as its toxic

Though K+ buffering = maintain ionic environment

Help form BBB

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14
Q

How do astrocytes provide energy for neurones?

A

Astrocytes supplements their supply of glucose

2 lactate is produced and transferred into the neurone

Lactate is then transformed into pyruvate

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15
Q

Why do astrocytes need to buffer K+?

A

High levels of neuronal activity = [K+] rise in brain ECF

Astrocytes take up the K+ to prevent this

Otherwise would change the pH and damage neurones

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16
Q

What cell type myelinate in the CNS vs the PNS?

A

CNS = oligodendrocytes

PNS = schwann cells

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17
Q

Outline the role of oligodendrocytes

A

Insulators

Responsible for myelinating the CNS

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18
Q

Describe microglia

A

Immunocompetent cells

Recognise foreign material = activated = change shape = phagocytose

Can act as APCs and present Ags to T cells that can enter the CNS

19
Q

What is the role of the blood brain barrier?

A

Limits diffusion from blood to brain extracellular fluid = maintain environment for neurones

Formed by tight junctions between endothelial cells in the capillary, surrounded by astrocytes

20
Q

What substances are transported across the BBB?

A

Glucose

AA

K+

21
Q

What substances can get freely through the BBB?

A

H2O

O2

CO2

Hormones

22
Q

How does the immune system in the CNS vary from the immune response in the rest of the body?

A

CNS inhibits initiation of pro-inflam T cell response = don’t want to much inflam in a bone box

Does not undergo rapid rejection of allographs

23
Q

Outline the structure of a typical neurone

A

Cell soma

Dendrites

Axon

Terminals

24
Q

Describe the neruotransmitter release

A

Depolarisation in terminal = opens voltage-gated Ca2+ channels = Ca2+ ions enter terminal

Vesicles fuse = release transmitter

Neurotransmitter diffuses across the synaptic cleft = binds to receptors on postsynaptic membrane

25
Q

What types of receptors can be present on the postsynaptic membrane?

A

Ligand-gates

GPCR

26
Q

What are the 3 main classes of neurotransmitters?

A

AA

Biogenic amines

Peptides

27
Q

Describe AA neurotransmitters

A

Excitatory AA = glutamate

Inhib AA = GABA, glycine

28
Q

How can glutamate receptors be classified?

A

Ionotropic = ion channels permeable to Na+/K+, activation causes depolarisation

Metabotropic = GPCR, changes in IP3 or inhib of adenylate cyclase

29
Q

Explain glutamate receptors role in learning and memory

A

Activation of NMDA receptors (and mGluRs) can up-regulate AMPA receptors(initial fast depolarisation)

Strong, high frequency stimulation causes long term potentiation (LTP)

Ca2+ entry through NMDA receptors important for induction of LTP

30
Q

Where are inhibitory AA neurotransmitters found?

A

GABA – brain

Glycine – brainstem and spinal cord

31
Q

Explain how GABA and glycine receptors are inhibitory

A

GABA and glycine receptors have Cl channels

Open Cl = hyperpolarisation = inhibitory post-synaptic potential = decreased AP

32
Q

What drugs enhance the response to GABA?

A

Barbiturates = anti-epileptic

Benzodiazepines = sedative, anxiolytic

33
Q

What biogenic amines exist?

A

Acetylcholine

Dopamine

Noradrenaline

Serotonin (5-HT)

mostly act as neuromodulators

confined to specific pathways

34
Q

What is the role of acetylcholine as a neurotransmitter?

A

neuromuscular junction

ganglion synapse in ANS

postganglionic parasympathetic

35
Q

Outline the cholinergic pathways in the CNS

A

Pathway arising the the nucleus basalis (first to die in Alzheimer’s)

Projects throughout the cerebral cortex

Septal neurones projecting into the hippocampus (LTP)

Involved in arousal , learning & memory

36
Q

Outline the dopaminergic pathways in the CNS

A

Substantia nigra (first to die in parkinsons) to striatum involved in motor control

Mesolimbic pathway to amygdala and hippocampus – control of mood, arousal, reward

37
Q

What conditions are associated with dopamine dysfunction?

A

Parkinson’s = loss of dopaminergic neurones, treat: levadopa converted to dopamine

Schizophrenia = too much dopamine, treat: antagonists at dopamine D2 receptors

38
Q

Outline noradrenaline as a neurotransmitter

A

transmitter at postganglionic – effector synapse in ANS

Also acts as a neurotransmitter in the CNS

Operates through G protein-coupled α- and β-adrenoceptors

39
Q

Outline the noradrenergic pathways in the CNS

A

Locus coeruleus contain noradrengeneric neurones (pons/medulla)

Diffuse release of NA throughout

40
Q

Outline how noradrenaline effects behavioural arousal

A

Locus ceruleus inactive during sleep

Activity increases during behavioural arousal

Depression associated with deficiency of NA

41
Q

Where does noradrenaline come from?

A

NA comes from neurones in the locus ceruleus

42
Q

Outline the serotonergic pathways in the CNS

A

Serotonin from the raphe nuclei to the rest of the brain

Function: sleep/wakefulness, mood

43
Q

What can be used for the treatment of depression and anxiety disorders

A

SSRIs = selective serotonin reuptake inhibitors

2.4.1. Nervous System (20 decks)

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