3. Neurotransmitters Flashcards

1
Q

Neurotransmitters

A

chemical substances that move messages across the synapse. More than 100 substances.

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2
Q

What are the functions of neurotransmitters?

A

excitatory or inhibitory depending on their receptor (there are many subtypes that may have very different responses)

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3
Q

what are small-molecule neurotransmitters?

A

amino acids
monoamines
acetylcholine
Unconventional neurotrasmitters

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4
Q

neuropeptides

A
pituitary peptdes
hypothalamic peptides
brain-gut peptides
opioid peptides
miscellaneous peptides
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5
Q

what are the most common amino acids?

A

amino acids

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6
Q

excitatory neurotransmitters that are amino acids

A

glutamate and asparate

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7
Q

inhibitory neurotransmitters that are amino acids

A

Gamma-aminoburytic acid (GABA) and glycine

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8
Q

how are amino acids distributed

A

widely through the CNS

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9
Q

Glutamate involved in…

A

especially involved in learning through a particular receptor-type (NMDA receptors). Involved in excitoticity - prolonged depolarisation of postsynaptic cell -> neuron death

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10
Q

two classes of monoamines

A

catecholamines and indolamines (based on structure)

Most of them diffusely released into extracellular fluid

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11
Q

catecholamines

A

dopamine, epinephrine, norepinephrine;

All derived from one amino acid - tyrosine

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12
Q

indolamines

A

Serotonin or 5-HT (melatonin)

derived from tryptophan

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13
Q

two pathways of dopamine

A

two pathways are mesostriatal and mesolimbocortical

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14
Q

functions of dopamine

A
reward (motivation)
pleasure, euphoria
motor function (fine tuning)
compulsion
Perservation
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15
Q

Mesostriatal pathway

A

Dopamine from the substantia nigra to the striatum

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16
Q

mesolimbocortical

A

from the VTA to the hippocampus, nucleus accumbens and frontal cortex

17
Q

behavioural effects of serotonin

A
mood
perception
memory
anger
aggression
fear
stress responses
appetite
addiction
sexuality
sleep
cognition
18
Q

seratonin pathway

A

Raphe nucleus to the striatum, nucleus accumbens, frontal cortex, hippocampus,

19
Q

what was the first neurotransmitter to be detected?

A

acetylcholine (ACh)

20
Q

What is acetylcholine usually referred to as?

A

the cholinergic system (i.e. acetylcholine-containing)

21
Q

what are ACh receptors usually?

A

either nicotinic or muscarinic

22
Q

nicotinic

A

ionotropic; excitatory

23
Q

muscarinic

A

metabolic; both excitatory and inhibitory

24
Q

what is Acetylcholine implied in?

A

Alzheimer’s disease; learning and memory

25
what is the cholinergic system?
projections of cholinergic neurons from the chollinergic nuclei of the pons and midbrain to the hippocampus, thalamus and amygdala and also from the basal forebrain to the cerebral cortex
26
two kinds of unconventional neurotransmitters
nitric oxide, carbon monoxide Endocannabinoids
27
Nitric Oxide, carbon monoxide
soluble gaseous neurotransmitter easily penetrate the cell membrane and active second messengers involved in retrogade transmission
28
endocannabinoids
includes anandamide - which was the first endocannabinoid to be discovered with similar properties to the main psychoactive properties of marijuana The major effect on presynaptic neurons inhibiting synaptic transmission
29
how many neuroptides are identified?
about 100
30
what do the neuropeptides functions depend on?
their amino acid sequence
31
5 categories of neuroptides
``` pituitary peptides hypothalamic peptides brain-gut peptides opiate peptides miscellaneous hormones ```
32
pituitary peptides
those released from the pituitary gland (e.g. oxytocin; "love" hormone
33
hypothalamic peptides
those released from the hypothalamus (e.g. CRH; corticotropin releasing hormone; anxiety)
34
brain-gut peptides
those first identified in the gut (e.g. ghrelin; hunger hormone also thought to be involved in stress, anxiety, depression; learning etc.)
35
opiate peptides
those that resemble the structure of active ingredient of opium (endogenously produced; (e.g. endorphins; happy hormones)
36
miscellaneous hormones
those that dont fit any other category
37
how do drugs influence synaptic transmission
drugs either facilitate (agonists) or inhibit (antagonist) effects of neurotransmitters. Drugs can act on various steps of neurotransmitter action either pre or post synaptically
38
what are the 7 steps to neurotransmitter action
1. neurotransmitter molecules are synthesised from precursors under the influence of enzymes 2. neurotransmitter molecules are stored in vesicles 3. neurotransmitter molecules that leak from their vesicles are destroyed by enzymes 4. action potentials cause vesicles to fuse with the presynaptic membrane and release their neurotransmitter molecules into the synapse 5. Released neurotransmitter molecules bind with autoreceptors and inhibit subsequent neurotransmitter release 6. Released neurotransmitter molecules bind to postsynaptic receptors 7. Released neurotransmitter molecules are deactivated by either reuptake or enzymatic degradation