Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neurophysiology > Neurotransmitter systems III: Monoamines > Flashcards

Neurotransmitter systems III: Monoamines Flashcards

1
Q

What are the central nervous systems which controls behaviour?

A

Autonomic Nervous System

Hypothalamic-Pituitary Neurohormones

Diffuse Monoamine Modulatory System

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the Diffuse monoamine modulatory systems?

A

4 monoamine modulatory systems:

  • Noradrenaline: Noradrenergic Locus Coeruleus
  • Serotonin (5-HT): Serotonergic Raphe Nuclei
  • Dopamine: Dopaminergic Substantia Nigra and Ventral Tegmental Area
  • Acetylcholine: Cholinergic Basal Forebrain and Brain Stem Complexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do the 4 diffuse modulatory systems have in common?

A

Ø Released from neurones which arise from brain stem
Ø Neurones project from central core where cell bodies are located to many different regions of the brain where the neurotransmitter gets released
Ø One neurone influences many others
Ø Synapses release transmitter molecules into extracellular fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of receptors are monoamine receptors?

A

G-protein coupled receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the Noradrenergic modulatory pathway.

A

noradrenergic neurones project from central core called Locus Coerulus to different brain regions (e.g. cortex, amygdala, hypothalamus, cerebellum, spinal cord)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the Action of noradrenaline at synaptic bouton.

A

1) Noradrenaline gets into synaptic vesicles
2) Noradrenaline released upon stimulation by action potential
3) Noradrenaline binds to post-synaptic noradrenergic receptors (G-coupled) to carry on the message
4) Noradrenaline also activates pre-synaptic auto-receptors (a2 receptors) which act via a negative feedback mechanism and inhibit the release of noradrenaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the Effects of increased noradrenaline?

A
  • Cardiovascular effects (tachycardia, high blood pressure)
  • Addictive-like behaviour (gambling)
  • Hyperarousal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the Effects of decreased noradrenaline?

A
  • Depression

- Parkinson’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe process of Noradrenaline Regulation: Reuptake mechanism.

A

noradrenaline transporters on pre-synaptic membrane reuptake excess noradrenaline from synapse

once inside the synapse, noradrenaline is metabolised and broken down by monoamine oxidase (MAO), terminating its action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the structure of Noradrenaline receptors.

A

G-protein coupled receptors:

  • Alpha 1 (Gq)
  • Alpha 2 (Gi)- autoreceptors
  • Beta (Gs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the Drugs that increase noradrenaline levels?

A

· Reserpine: depletes noradrenaline stores by inhibiting vesicular uptake

· Amphetamine (indirect sympathomimetic): enters vesicles displacing NA into cytoplasm, increasing NA leakage out of neurone into synapse

· Cocaine: blocks NA reuptake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the Action of drugs in depression treatment.

A

Drugs to increase noradrenaline:

  • block monoamine oxidase (MOA)
  • block noradrenaline transporters
  • block serotonin transporters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the Dopaminergic Modulatory Pathways?

A

Nigrostriatal Pathway

Mesolimbic Pathway

Mesocortical Pathway

Tubero-hypophyseal Pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the Nigrostriatal pathway.

A

dopaminergic neurones project from substantia nigra (SN), where cell bodies are found, to the striatum where dopamine is released to induce MOVEMENT

*degeneration of these neurones decreasing dopmaine levels in the striatum, causing Parkinson’s disease (suppressed movement)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the Mesolimbic pathway.

A

dopaminergic neurones project from ventral tegmental area (VTA) to amygdala, hippocampus and nuclear accumbens, where dopamine is released to induce REWARD (e.g. food, sex)

  • Abused drugs over-stimulate this pathway, increasing pleasure/reward, leading to addiction
  • Hyperactivity of this system causes psychotic episodes in schizophrenics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the Mesocortical pathway.

A

dopaminergic neurones project from ventral tegmental area (VTA) to the cortex, where dopamine is released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the Tubero-hypophyseal pathway..

A

dopaminergic neurones project from hyopthalamus to the portal capillary system in the median eminence where dopamine is released, acting as a neurohormone by binding to its receptors in the anterior pituitary and inhibiting release of prolactin

*prolactin responsible for mammary gland enlargement and milk production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Dopamine is involved in…

A 
addiction (gambling)
emesis
ADHD
Schizophrenia (hyperactivity of mesolimbic pathway)
Parkinson's disease (lack of dopamine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the porcess of Synthesis of Catecholamines.

A

1) Tyrosine is converted to DOPA by tyrosine hydroxylase
2) DOPA is converted to dopamine via DOPA decarboxylase
3) Dopamine is then metabolised to noradrenaline via Dopamine-β hydroxylase
4) Noradrenaline can then further be metabolised to adrenaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What determines whether a neurone is dopaminergic or noradrenergic?

A

The presence of Dopamine-β hydroxylase in excess makes neurones dopaminergic

Neurones without this enzyme are noradrenergic

21
Q

What are the Effects of increased dopamine?

A

addiction

psychosis

22
Q

What are the Effects of decreased dopamine?

A

Parkinson’s disease

23
Q

Describe the process of Dopamine Regulation: Reuptake Mechanism.

A

dopamine transporters on pre-synaptic membrane reuptake excess dopamine from synapse

once inside the neurone, dopamine is metabolised and broken down by monoamine oxidase b (MOAb), terminating its action

24
Q

Describe the Actions of drugs in Parkinson’s treatment.

A

Drugs to increase dopamine:

  • block monoamine oxidase b (MOAb)
  • block dopamine reuptake transporters
25
Q

Describe the structure of Dopamine Receptors.

A

D1-like (Gs coupled)
>D1 & D5

D2-like (Gi coupled)
>D2, D3, D4

26
Q

Where are dopamine receptors are found?

A
  • Post-synaptic D1 and D2 receptors
  • Pre-synaptic D2 or D3 auto-receptors

· D1 and D2 receptors are found in the striatum, limbic system, thalamus and hypothalamus
· D3 receptors are found in the limbic system
· D4 receptors are found in the cortex and limbic system

27
Q

Dopamine is associated with…

A 
movement
addiction
stereotypy
hormone release
vomiting
28
Q

Describe the Serotonergic pathway.

A

serotonergic neurones project from central core called Raphe nucleus to regions such as cerebellum, cortex, striatum, hippocampus, amygdala, thalamus, hypothalamus, spinal cord, where serotonin is released

29
Q

What is the Effect of serotonin?

A

Different effects in different brain regions:

· Binds to receptors in cortex and causes heightened perceptions

· Binds to receptors in hypothalamus and reduces appetite

· Binds to receptors in amygdala and causes elevated mood

Other effects:

  • sleep/wake cycle
  • vomiting
  • psychosis
  • reducing pain, migraine
30
Q

Describe the Synthesis of Serotonin.

A

Precursor of serotonin is the amino acid tryptophan:

1) Tryptophan is metabolised by tryptophan hydroxylase to 5-hydroxytryptophan
2) 5-hydroxytryptophan is metabolised by L-Aromatic acid decarboxylase to serotonin (5-HT)
3) 5-HT can be metabolised further by monoamine oxidase to 5-hydroxyindoleacetylaldehyde
4) This metabolite can be further metabolised to 5-HIAA (5-hydroxyindoleacetic acid) by aldehyde dehydrogenase

31
Q

What are the Effects of low serotonin?

A

depression

32
Q

Describe the process of Serotonin Regulation: Reuptake Mechanism.

A

Serotonin transporters on pre-synaptic membranes reuptake excess serotonin from the synapse

once inside the neurone, the serotonin is metabolised and broken down by monoamine oxidase (MOA), terminating its action

33
Q

Describe the structure of Serotonin receptors.

A

Post-synaptic and pre-synaptic 5-HT receptors (14 subtypes):

-all G-protein coupled receptors apart from one (5-HT3) which is an ion channel

34
Q

Describe the structure of Monoamine Transporters.

A

These take the neurotransmitter back up into the pre-synaptic terminal.

  • 12 transmembrane domains
  • both ends intracellular
  • pump monoamines (NA, DA, 5HT) in neurone
35
Q

Describe the Cholinergic Modulatory Pathways.

A

Septohippocampal Pathway

-cholinergic neurones project from the septum to the hippocampus, where acetylcholine is released

Nucleus Basalis

-cholinergic neurones project from the nucleus basalis to the cortex where acetylcholine is released

Striatal Interneurons

-small cholinergic neurones called striatal interneurons found within the striatum release acetylcholine.

Substantia Nigra

-cholinergic neurones project from the substantia nigra to the thalamus, where acetylcholine is released.

36
Q

What are cholinergic neurones involved in?

A

cognition
learning
memory

37
Q

What does the degeneration of cholinergic neurones cause?

A

dementia and Alzheimer’s, causing for cognitive symptoms such as memory loss

38
Q

Describe the structure of Acetylcholine receptors.

A

Muscarinic (G-protein)

  • M1,3,5 excitatory
  • M2&4 inhibitory

Nicotinic (ligand-gated ion channels)

39
Q

Describe the process of Acetylcholine Regulation.

A

Acetylcholinesterase breaks down acetylcholine to choline and acetate, terminating its activity

Choline then is re-uptaken into pre-synaptic neurone to be recycled

40
Q

Describe the Action of drugs to treat dementia/Alzheimer’s.

A

Drugs increase acetylcholine levels:

-inhibit acetylcholinesterase enzyme

41
Q

Acetylcholine is involved in…

A 
arousal
epilepsy (mutations of nAChR genes)
learning and memory
motor control, pain, addiction
schizophrenia
ADHD
depression
anxiety
Alzheimer's
42
Q

Give some Other transmitters/modulator substances.

A 
Histamine
Purines
Neuropeptides
Lipid Mediators
Melatonin
43
Q

What are opioid peptides (neuropeptides) derived from?

A

a bigger protein e.g. β endorphin is derived from pro-opiomelanocortin (POMC)

once the peptide is released from the neurone it acts on receptors

44
Q

How are neuropeptides synthesized?

A
  • Encoded by DNA
  • Gene modified in rER and Golgi
  • Proteolytic cleavage in Golgi breaks down big proteins into many different peptides e.g. β endorphin, which are stored in synaptic vesicles for release upon stimulation
45
Q

Which drugs interact with the diffuse system?

A

Amphetamine (psychostimulant)

Cocaine (central stimulant)

46
Q

What are Amphetamine-like drugs?

A

methylphenidate & MDMA:

  • release cytosolic monoamines
  • prolonged use causes degeneration of nerves and death (neurotoxic)

Pharmacological effects:

  • increased alertness and locomotor stimulation (increased aggression)
  • stereotyped behaviour
  • anorexia
  • less physical and mental fatigue
  • increased blood pressure
  • decrease gastric motility
  • improved confidence/lack of tiredness
47
Q

Give some Therapeutic uses of amphetamine-like drugs.

A

Therapeutic uses:

  • ADHD (methylphenidate)
  • Appetite suppressants
  • Narcolepsy
48
Q

What is the effect of Cocaine?

A

blocks catecholamine reuptake, increasing dopamine at synapse

Pharmacological effects:

  • euphoria
  • locomotor stimulation
  • fewer stereotyped behaviour than amphetamine
  • heightened pleasure
  • lower tendency for delusions, hallucinations and paranoia

Neurophysiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions