CNS Transmission Flashcards Preview

MD1 Neuroscience > CNS Transmission > Flashcards

Flashcards in CNS Transmission Deck (42)
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1
Q

What are the sensory inputs?

A
External stimuli
- Sound
- Sight
- Smell
- Touch
- Taste
Internal stimuli
- Pressure
- O2/CO2
- Temperature
- pH
2
Q

What is an action potential?

A

Electrical signal along nerve

3
Q

What is a neurotransmitter?

A

Chemical signal at nerve ending

4
Q

What is the role of Ca at the pre-synaptic terminal?

A

Influx of Ca
Synaptic vesicles release neurotransmitter into synapse
Receptors detect and bind neurotransmitter

5
Q

What is the main pre-ganglionic autonomic neurotransmitter and receptor?

A

Acetylcholine

Nicotinic receptors

6
Q

What is the main sympathetic neurotransmitter and receptor?

A

Noradrenaline

a- and b-adrenoceptors

7
Q

What is the main parasympathetic neurotransmitter and receptor?

A

Acetylcholine

Muscarinic receptors

8
Q

What is the main somatic neurotransmitter and receptor?

A

Acetylcholine

Nicotinic receptors

9
Q

What are the requirements for chemical neurotransmission?

A
Synthesis/storage
- Vesicular content
Release
- Na and K ion channels
- Ca influx
Inactivation
- Uptake
- Metabolism
Receptors
- Pre-junctional
- Post-junctional
10
Q

How is noradrenaline inactivated at the synapse?

A

Neuronal uptake - predominant removal
Extraneuronal uptake
Metabolism - very small contribution

11
Q

What is the pre-junctional receptor for noradrenaline?

A

a2 receptor

12
Q

Can drugs with peripheral actions also have effects on the CNS?

A

Yes, and dramatic ones, too

But only if they cross the BBB

13
Q

Describe the uptake of noradrenaline at the synapse

A
Neuronal
- High affinity
- 90-95%
Extraneuronal
- Low affinity
14
Q

What does cocaine do at the synapse?

A

Block neuronal uptake of NA

Increased response when nerves activated

15
Q

Does cocaine have dose-response effects?

A
Yes
South American Indians chewed leaf
- Slow absorption
- Low concentration
- Relief from
   - Fatigue
   - Hunger
   - Altitude sickness
- Pleasant subtle sense of well being
- Psychological dependence
Western society snorts, smokes, injects
- Fast absorption
- High concentration
- Intense euphoria
- Craving for more drug
- Psychological and physical dependence
- Psychotic symptoms, depression, anxiety, fatigue
- Peripheral effects: hypertension, tachycardia, coronary vasospasm, dysrhythmia, convulsions
16
Q

What does amphetamine do at the synapse?

A

Displace noradrenaline from storage vesicles
- NA released even during low activity
Competes for uptake receptors

17
Q

What are the functions associated with noradrenaline?

A

Stimulant
Mood
Appetite
Cardiovascular

18
Q

What are the catecholamines?

A

Noradrenaline
Dopamine
Adrenaline

19
Q

What type of chemical is serotonin?

A

Amine

20
Q

What are the amino acid neurotransmitters?

A

GABA
Glutamate
Glycine
Aspartate

21
Q

What are the peptide neurotransmitters?

A

Opioids
NPY
CCK

22
Q

What is a gaseous neurotransmitter?

A

Nitric oxide

23
Q

Which neurotransmitter, unlike others, is made on demand?

A

Nitric oxid

24
Q

What is the distribution of neurotransmitters?

A

Some widespread

Others highly localised

25
Q

Describe catecholamine synthesis

A

EC: Tyrosine
IC: Tyrosine hydroxylase > L-DOPA > doa decarboxylase > dopamine
Vesicle: Dopamine-b-hydroxylase > NA > phenyl-ethanolamine-N-methyl transferase > adrenaline

26
Q

In which cells is adrenaline synthesised?

A

Adrenal chromaffin cells

27
Q

Which nerves synthesises dopamine only?

A

Dopaminergic nerves

28
Q

Where are some areas of the brain to which noradrenergic pathways project?

A

Cerebellum
Caudal raphe nuclei
Thalamus

29
Q

Where are some areas of the brain to which dopaminergic pathways project?

A

Striatum

Pre-frontal cortex

30
Q

What are some of the pathways in which dopamine is involved?

A
Movement
- Parkinson's: depletion of dopamine in basal ganglia
Behaviour:
- Schizophrenia: changes in dopamine rich areas like:
   - Frontal cortex
   - Basal ganglia
   - Temporal lobe
Dependence:
- Dopamine actions in nucleus accumbens and ventral tegmental area
Pituitary function
- Prolactin secretion
Vomiting
- Chemoreceptor trigger zone outside BBB
- Less important
31
Q

What neurotransmitter uptake does cocaine block?

A

Noradrenaline
Dopamine
Serotonin

32
Q

What is cocaine’s dopaminergic action linked to?

A

Dependence

33
Q

What type of channel does cocaine also block?

A

Na channels

Happens at much higher concentrations

34
Q

Can a synapse be excitatory AND inhibitory?

A

No, can only be one or the other

35
Q

Can a neurotransmitter be excitatory AND inhibitory?

A

Yes, depending on which receptor is present

36
Q

What type of receptor is a nicotinic receptor?

A

Ligand-gated ion channel
Excitatory
Na influx driven depolarisation

37
Q

What type of receptor is a GABA A receptor?

A

Ligand-gated ion channel
Inhibitory
Cl influx driven hyperpolarisation

38
Q

What are post-synaptic receptors responsible for?

A

Action potential generation/modulation

39
Q

What are pre-synpatic receptors responsible for?

A

Transmitter release

40
Q

What are neurotrophic factors secreted by glial cells involved in?

A

Development

Survival

41
Q

What is the role of glia in neurodegenerative diseases?

A

Loss of neuroprotective factors

Toxic insult

42
Q

What complicates the rational approach to identifying transmitter levels in disease

A

More than one transmitter usually involved
One transmitter involved in many pathways
Secondary/adaptive responses
Effect of transmitter levels on
- Synthesis
- Receptor expression
- Transporter expression

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