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Scientific foundations Of neuropsychiatry > Neurochemistry > Flashcards

Neurochemistry Flashcards

1
Q

What is the role of astrocytes?

A

Modify synapses
Control potassium ions
Control BBB
Neurotransmitter reuptake

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2
Q

What is the role of oligodendrocytes?

A

They form the myelin sheath of multiple neurons

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3
Q

What is the role of microglia?

A

Resident immune cells of the CNS
Engage in phagocytosis

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4
Q

What is the role of ependymal cells?

A

Ependymal cells line the ventricles
Produce monitor and circulate CSF

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5
Q

What is the role of vascular epithelial cells?

A

Line blood vessels and form part of the BBB

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6
Q

Where are axons located?

A

Distal to the cell body

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7
Q

Where are dendrites thpically located?

A

At the cell body

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8
Q

What are the three main divisions of neurons (polarity)?

A

Bipolar (olfactory, retinal)
Multipolar (purkinje, pyramidal)
Unipolar (dorsal root ganglion)

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9
Q

What kind of circuits exist in the CNS?

A

Divergence
Same pathway
Multiple pathways

Convergence
Multiple sources
Single source (multiple synapses between same two neurons)

Reverberating circuit (feedback system)

Parallel after discharge circuit

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10
Q

Where are vesicles stored?

A

Presynaptic terminal

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11
Q

Where are neurotransmitters made?

A

Cell body

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12
Q

What are the two forms of axonal transport?

A

Slow (1-5mm/day)
Fast (200-400mm/day) - neurotransmitters, growth factors, toxins, viruses

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13
Q

What are the three types of synapse?

A

Axodendritic - axon to dendrite
Axosomatic - axon to cell body
Axoaxonic- axon to axon

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14
Q

What are the two types of receptor?

A

Ionotropic - ligand-gated ion channels

Metabotropic - GPCRs

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15
Q

How do ligand gated ion channels function?

A

The binding of a ligand (eg neurotransmitter) changes the shape of the receptor, opening a channel for ions to flow through

Fast effects

Examples: NMDA, AMPA

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16
Q

How do metabotropic receptors function?

A

Agonist activates receptor
G protein is activated and produces effector
Effector stimulates 2nd messenger synthesis
2nd messenger activates intercellular process

Indirect, slower effect

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17
Q

What is the canonical 2nd messenger?

A

Cyclic AMP

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18
Q

On what level does a neurotransmitter work?

A

Single neuron/receptor level

Excitatory - depolarised the membrane and increases the probability of an action potential on that neuron

Inhibitory - hyperpolarises the membrane and decreases the probability of an action potential on that neuron

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19
Q

What would be the effect of serotonin acting on Gi coupled receptor?

A

Inhibitory

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20
Q

How might excitatory dopamine have an inhibitory effect in a circuit?

A

Activation of the D1 receptor on a GABA-ergic neuron would increase GABA release at the synapse

GABA would inhibit a downstream glutamatergic neuron

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21
Q

What are the different forms of control of neurotransmitter release?

A

Activity dependent - neuronal firing rate alters NT concentration at cell body, auto receptors modulate firing rate in turn

Concentration dependent - presynaptic auto receptors can modulate excitability and NT release

Other transmitters - NTs from other terminals activate pre synaptic heteroreceptors (serotonin receptor stimulation at noradrenergic terminals can trigger noradrenaline release)

22
Q

How might neurotransmitter activity be terminated?

A

Dissociation from receptor

Receptor internalisation

Synaptic neurotransmitter concentration drops
-diffusion
-reuptake
-catabolism (AChE, MAO)

23
Q

What type of neurotransmitters are there?

A

Amino acids - glutamate, GABA, glycine

Gasotransmitters - NO, CO

Monoamines - serotonin, dopamine, noradrenaline, histamine

Trace amines

Peptides - opioids

Purines - ATP, adenosine

Cannabinoids - anandamine, CBD, THC

Acetylcholine

24
Q

What ion channels are GABA associated with?

A

Chloride
Potassium

25
Q

What ion channels are glutamate associated with?

A

Cations - sodium, potassium, calcium

26
Q

How do benzodiazepines affect GABA activity?

A

Modulate GABA receptors to increase the efficacy of GABA

27
Q

How is glutamate implicated in neurodegeneration?

A

Excitotoxicity from increased glutamate release causing cell damage and death

28
Q

What is the function of nicotinic acetylcholine receptors?

A

Excitatory (ionotropic)

29
Q

Cell bodies in which areas are dopaminergic?

A

Substantial nigra
Ventral tegmental area

30
Q

What receptors does dopamine associate with?

A

GPCRs

31
Q

Which dopamine receptor is excitatory?

A

D1 only
The most widespread

32
Q

How do amphetamines, cocaine, and methylphenidate (ADHD medication) act?

A

Inhibit dopamine transporters
Increase synaptic dopamine

33
Q

What enzyme breaks down extracellular dopamine? (Clue: which inhibitor is used to make L-DOPA more effective?)

A

COMT

34
Q

Why is L-DOPA used as treatment instead of dopamine?

A

Dopamine can’t cross BBB
(Also has effects on heart rate)

35
Q

Where are the noradrenergic neurons located?

A

Locus coeruleus

36
Q

In what ways are noradrenaline and dopamine related?

A

Structurally similar
NAT transporters are inhibited by same antagonists as DAT transporters
Both broken down intracellularly by MAO
Both broken down extracellularly by COMT

37
Q

Where are serotonergic neurons located?

A

Raphe nuclei

38
Q

What drugs block Serotonin reuptake transporters (SERTs)?

A

MDMA
Amphetamine
Cocaine
TCAs
SSRIs

39
Q

Where are histaminergic neurons located?

A

Tuberomammillary nuclei in the posterior hypothalamus

40
Q

What does histamine regulate? (Think about where the neurons are located)

A

Sleep, appetite, body temperature

41
Q

What neuropsychiatric disorder is histamine implicated in

A

Schizophrenia

42
Q

How does caffeine act on dopamine?

A

Caffeine blocks adenosine receptors
Adenosine unable to block D2 receptors
Increased effect of dopamine

43
Q

What receptors do heroin and other opiates work on?

A

Mu opioid receptors

44
Q

What is the endogenous counterpart of THC?

A

Anandamide

45
Q

What is the endogenous counterpart of CBD?

A

2AG

46
Q

What do cannabinoids regulate?

A

Motivation
Pleasure
Feeding behaviour

47
Q

Where do new experiences effect change in the CNS?

A

At the synapses

48
Q

What is the Hebbian theory maxim?

A

Neurons that fire together wire together

49
Q

What is the role of NMDA in synaptic plasticity (long term potentiation?)

A

At resting membrane potential ion flow at NMDA is blocked by Mg2+

Depolarisation of the post synaptic membrane displaces Mg2+

Ca2+ influx activates 2nd massagers

Patterns of this influx influence synaptic plasticity

50
Q

How are SPECT and PET imaging used in neurochemistry?

A

Radioactive tagging (Carbon-11) of a ligand that will bind to a particular receptor

Effectively radiotagging each receptor
Allows for quantification if receptors

Scientific foundations Of neuropsychiatry (26 decks)

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