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Fundamentals of neuroscience > Neurochemisty (cells of NS) > Flashcards

Neurochemisty (cells of NS) Flashcards

1
Q

What is the other name for ionotropic receptors?

A

Ligand gated ion channels

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2
Q

What is the structure of ionotropic receptors like?

A
  • Transmembrane ion channel
  • Made up of 3, 4, or 5 subunits (form a channel w a hole)
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3
Q

What makes ionotropic receptors open?

A

Opens in repsonse to bidning of the specific NT on its extracellular side

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4
Q

What do ionotropic receptors allow to pass through?

A

Allows ions e.g. Na+, Ca2+ and Cl- to pass across the membrane

Results in membrane depolarisation or hyperpolarisation

Rapid response

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5
Q

Which of; depolarisation and hyperpolarisation is inhibitory and which is excitatory?

A

Depolarisation = excitatory

Hyperpolarisation = inhibitory

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6
Q

What is the other name for metabotropic receptors?

A

G protein receptors

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7
Q

What are metabotropic receptors made up of?

A

7 transmembrane domains

Receptors is not an ion channel but is indirectly associated w ion channels via a G protein via a series of intracellular events using second messengers = opening of channel

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8
Q

What are the types of G proteins?

A

Gi - inhibitory
Gs = stimulatory
Gq = stimulatory

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9
Q

Which responds faster; ionotropic or metabotropic?

A

Ionotropic

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10
Q

What are the 4 umbrella groupd of NTs?

A
  • Animo acids (non-essential)
  • Amines
  • Purines
  • Neuropeptides
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11
Q

What are the amino acid NTs?

A
  • Glutamate
  • GABA
  • Glycine
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12
Q

What are the Amine NTs?

A

Monoamines:
- ACh
- Serotonin
- Histamine

Catecholamines
- Dopamine
- Noradrenaline
- Adrenaline

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13
Q

What are the purine NTs?

A
  • Adenosine
  • ATP
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14
Q

What are the neuropeptides NTs?

A

Huge class of them

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15
Q

What is the process of the formation of amino acid glycine?

A

Glucose –> Pyruvate –> Serine –> Glycine

Glycine Hydroymethyl Transferase is used between serine & glycine

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16
Q

What is the process of the formation of amino acid GABA?

A

Glucose –> Pyruvate –> Acetyl CoA –> TCA cycle –> alpha-ketoglutarate –> glutamate –> GABA

Glutamate dehydrogenase between ak and glutamate

Glutamic acid decarboxylase between glutamate & GABA

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17
Q

What is the most commone excitatory NT in the brain?

A

Glutamate

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18
Q

What % of neurones use glutamate as a NT?

A

90%

80-90% of synapses are glutamate

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19
Q

What can glutamate not pass?

A

The blood brain barrier (BBB) –> it is synthesised in the presynaptic terminal

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20
Q

What is glutamate uptake & recycling called and what does it involve?

A

Glutamate-glutamine cycle

It involves astrocytes = GLT

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21
Q

What are the types of glutamate receptors?

A

Ionotropic glutamate receptors (IGluR)
- NMDA
- AMPA
- Kainate

Metabotropic glutamate receptors (mGluR)
- Group I
- Group II
- Group III

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22
Q

What is excitotoxictiy?

A

Overactivation of glutamate receptors (NMDA) –> induces neuronal cell death

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23
Q

What are the mechanisms in place to control excitotoxictiy?

A
  • When glutamate binds, causes morphological change, we don’t want too much so there is an additional magnesium block
  • Magnesium in centre doesn’t allow ions to pass through, needs to be removed
  • Glutamate binds to AMPA receptors first, causes depolarisation & removal of magnesium block
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24
Q

What is the most common inhibitory NT?

A

GABA –> 1/3 of neurones use GABA as a NT

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25
Q

Where is GABA synthesised?

A

In the presynaptic terminal

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26
Q

Where does GABA uptake happen?

A

In the presynaptic terminal & astrocytes –> GAT

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27
Q

What are the types of GABA receptors?

A

GABAA –> ligand-gates ion channel

GABAB –> G protein-coupled receptor

GABAC –>Ligand-gated ion channel

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28
Q

What is GABA a target for?

A

Benzodiazepines

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29
Q

Where is glycine most commonly found?

A

Most commone inhibitory NT in the spinal cord & brain stem

Expressed by interneurones in the spinal cord

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30
Q

Where is glycine synthesised?

A

In the presynaptic terminal

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31
Q

Where does glycine uptake happen?

A

In the presynaptic terminal –> GlyT a glycine specific transporter

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32
Q

What is the ionotropic receptor for glycine called?

A

GlyR –> receptor that binds to the NT glycine

Is an inhibitory receptor - dysfuntion linked to autism

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33
Q

What is glycine a co-agonist with?

A

Glutamate NMDA recpetors = work together to regulate the activity of neurones in the brain

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34
Q

Where is ACh found?

A

Widely distributed around the CNS

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35
Q

What is ACh used for?

A
  • Arousal
  • Attention
  • Memory
  • Motivation
36
Q

What neurodegenerative disease is linked to ACh?

A

Alzheimer’s –> as ACh is important for learning and memory

37
Q

What is ACh important for as the primary NT of the PNS?

A
  • Vasodilation of vasculature
  • Contraction of smooth muscle e.g. iris & lens ciliary muscle of eye
  • Secretion of body fluids e.g. tears, saliva & sweat
  • Slows HR
  • Inc GI tone & secretions
38
Q

Which NT is the primary NT at junctions?

A

ACh - at choliergic synapses

39
Q

What are the stages of producing Acetlycholine?

A

Glucose –> Pyruvate –> Acetly CoA –> Aceytl (CoA lost) –> choline added = Acetyl choline

40
Q

How is ACh broken down?

A

By an enzyme acetlycholinesterase (AChE)

Broken down into choline & acetate –> choline taken back up to make more ACh

41
Q

What are the 2 types of ACh receptors?

A
  • Nicotinic receptors (nAChR)
  • Muscarinic receptors (mAChR)
42
Q

What are nicotinic receptors?

A

Type of ionotropic receptoractivated by ACh & nicotine

Found on cell bodies & dendrites of postganglionic neurones - cause wave of deoplarisation in postganglionic neurone if they allow an influx of +ive ions

43
Q

What is the antagonist for nicotinic receptors?

A

Bungarotoxin:

Able to act on these receptors, inhibits action = no contraction of muscles, causes paralysis - this is used in snake venom

44
Q

What is the agonist for muscarinic receptors?

A

Muscarine

45
Q

What is the antagonist for muscarinic receptors?

A

Atropine

Commonly used for ppl with heart conditions –> specifically w low HR

46
Q

What is a muscarinic receptor?

A

A type of metabotropic receptor activated by ACh & muscarine

Found oneffector organs that are innervated by the PNS

Involved in learning, memory, attention & regulation of mood

47
Q

What is the agonist for nicotinic receptors?

A

Nicotine

48
Q

What inhibits the reuptake of serotonin?

A

SSRIs e.g. fluoxetine

49
Q

Where are cell bodies of serotonergic neurones found?

A

In the raphe nucleus of the brain stem

Their axons project to nearly every part of the brain (only used about 1% of the time)

50
Q

What are the functions of serotonin?

A

Mood, sleep ad appetite

51
Q

What is serotonin synthesised from?

A

The amino acid tryptophan

52
Q

Why shouldn’t you eat cheese before bed?

A

Cheese (specifically cheddar) has high amounts of Tryptophan which forms serotonin & causes funny dreams

53
Q

What are the receptors for serotonin called?

A

5-HT receptors - they perform differet physiological processes based on where they’re found in the body

54
Q

Where are histaminergic neurones found?

A

Cell bodies of histaminergic neurones found in the tuberomamillary nucleus of the posterior hypothalamus

Their axons project to nearly every part of the brain & spinal cord

55
Q

What is a prominet role of histamines?

A

Promoting wakefulness

By binding to H1 histamine receptors on wake promoting neurones, they are taken back up by H3 histamine receptors on the presynaptic neurone

56
Q

Where are histamines synthesised?

A

Synthesised by neurones from non-essential amino acid histidine

57
Q

What are the effects of histamines mediated by?

A

GPCRs : H1R - H3R

58
Q

How is histamine formed?

A
  • Formed from the amino acids histadine through a process called decarboxylation –> removes carboxyl group form the histidien molecules
  • Process is catalysed by an enzyme called histidine decarboxylase
  • Once formed it is stored in vesicles in the cell until it released in response to a stimulus
59
Q

What are the 4 main dopamine pathways in the brain?

A
  • Mesolimbic pathway
  • Mesocortical pathway
  • Nigrostriatal pathway
  • Tuberoinfundibular pathway
60
Q

What is the mesolibic pathway for?

A

Major reward pathway

61
Q

What is the mesocortical pathway for?

A

Executive functions

62
Q

What is the nigrostraital pathway for?

A

Movement

Loss of dopamine neurones in substantial nigra = Parkinson’s disease

63
Q

What is the tuberoinfundibular pathway for?

A

Prolactin secretion from pituitary gland

Prolactin plays important role in stimulating production of milk after birth

64
Q

Where does dopamine uptake happen?

A

In the presynaptic terminal via DAT

65
Q

What are the metabotropic receptors for dopamine?

A

D1-like receptors & D2-like receptors

66
Q

Dopamine synthesis

A

Pls refer to notes

67
Q

Where are cell bodies of noradrenic neuones?

A

In the locus coerulus of the brain stem

Thier axons project to nearly every part of the brain and spinal cord

68
Q

What does noradrenaline do?

A

Alertness, arousal, attention

69
Q

What is the primary NT in the sympathetic NS?

A

Noradrenaline

Used in the fight or flight response

70
Q

Where is noradrenaline synthesised?

A

In neurones

71
Q

Where doe noradrenaline uptake happen?

A

Into presynaptic terminal = NET

72
Q

What are the metabotropic receptors for noradrenaline?

A

Alpha and beta

73
Q

How can noradrenaline receptors be used to treat medical conditions?

A

Beta blockers –> used for heart conditions

Beta agonists e.g. salbutamol –> asthma treatment

74
Q

Where are cell bodies of adrenergic neurones found?

A

In the medulla of the brain stem

Their axons project to the thalamus, hypothalamus & spinal cord

75
Q

What triggers the release of adrenaline?

A

The sympathetic nervous system triggers its release from adrenal glands

Fight or flight response

76
Q

Where is adrenaline synthesised?

A

In neurons only in the medulla oblongata of the brain stem

77
Q

Where does adrenaline uptake happen?

A

In the presynaptic terminal

78
Q

What does adrenaline bind to?

A

Noradrenaline metabotropic receptors –> alpha and beta

79
Q

What is a purine NT?

A

An excitatory cotransmitter in the autonomic NS

Inhibitory BT in the enteric NS

80
Q

What is purine a cotransmitter with?

A

Various other NTs in the brian e.g. glutamate, dopamine, serotonin

81
Q

Descibe the action of purines

A
  • ATP present in vesicles & when released acts directly on receptors & broken down to adenosine by extracellular ATPase
  • Adenosine can then act on receptors and is taken back up into the neuron for ATP resynthesis
  • Adenosine metabotropic receptors = P1
  • ATP ionotropic receptors = P2X
  • ATP metabotropic receptors = P2Y
  • Sympathetic nervous system triggers its release from adrenal glands
82
Q

What are neuropeptides?

A

Chemical messengers made up of small chains of amino acids –> 3 to 36 amino acids long

Coexist in neurones w one or more NT

83
Q

Where are neuropeptides synthesised?

A

In cell body of neurones from large presursor proteins

Packaged into large dense core vesicles

84
Q

What are neuropeptides released in response to?

A

In response to repetivite AP firing

85
Q

What are neuropeptides generally like?

A
  • No reuptake in the neurone
  • Response = slow & prolonged
  • Tend to act viametabotropic receptors
  • Over 100 known neuropeptides
  • Various roles
86
Q

Give an example of a neuropeptide w various roles

A

Neuropeptide Y

  • Sympathetic NS = vasoconstrictor
  • Hypothalamus = food intake

Fundamentals of neuroscience (38 decks)

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