CNS Transmission Flashcards Preview

MD1 Neuroscience > CNS Transmission > Flashcards

Flashcards in CNS Transmission Deck (42):
1

What are the sensory inputs?

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

2

What is an action potential?

Electrical signal along nerve

3

What is a neurotransmitter?

Chemical signal at nerve ending

4

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

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

5

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

Acetylcholine
Nicotinic receptors

6

What is the main sympathetic neurotransmitter and receptor?

Noradrenaline
a- and b-adrenoceptors

7

What is the main parasympathetic neurotransmitter and receptor?

Acetylcholine
Muscarinic receptors

8

What is the main somatic neurotransmitter and receptor?

Acetylcholine
Nicotinic receptors

9

What are the requirements for chemical neurotransmission?

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

10

How is noradrenaline inactivated at the synapse?

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

11

What is the pre-junctional receptor for noradrenaline?

a2 receptor

12

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

Yes, and dramatic ones, too
But only if they cross the BBB

13

Describe the uptake of noradrenaline at the synapse

Neuronal
- High affinity
- 90-95%
Extraneuronal
- Low affinity

14

What does cocaine do at the synapse?

Block neuronal uptake of NA
Increased response when nerves activated

15

Does cocaine have dose-response effects?

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

What does amphetamine do at the synapse?

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

17

What are the functions associated with noradrenaline?

Stimulant
Mood
Appetite
Cardiovascular

18

What are the catecholamines?

Noradrenaline
Dopamine
Adrenaline

19

What type of chemical is serotonin?

Amine

20

What are the amino acid neurotransmitters?

GABA
Glutamate
Glycine
Aspartate

21

What are the peptide neurotransmitters?

Opioids
NPY
CCK

22

What is a gaseous neurotransmitter?

Nitric oxide

23

Which neurotransmitter, unlike others, is made on demand?

Nitric oxid

24

What is the distribution of neurotransmitters?

Some widespread
Others highly localised

25

Describe catecholamine synthesis

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

26

In which cells is adrenaline synthesised?

Adrenal chromaffin cells

27

Which nerves synthesises dopamine only?

Dopaminergic nerves

28

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

Cerebellum
Caudal raphe nuclei
Thalamus

29

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

Striatum
Pre-frontal cortex

30

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

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

What neurotransmitter uptake does cocaine block?

Noradrenaline
Dopamine
Serotonin

32

What is cocaine's dopaminergic action linked to?

Dependence

33

What type of channel does cocaine also block?

Na channels
Happens at much higher concentrations

34

Can a synapse be excitatory AND inhibitory?

No, can only be one or the other

35

Can a neurotransmitter be excitatory AND inhibitory?

Yes, depending on which receptor is present

36

What type of receptor is a nicotinic receptor?

Ligand-gated ion channel
Excitatory
Na influx driven depolarisation

37

What type of receptor is a GABA A receptor?

Ligand-gated ion channel
Inhibitory
Cl influx driven hyperpolarisation

38

What are post-synaptic receptors responsible for?

Action potential generation/modulation

39

What are pre-synpatic receptors responsible for?

Transmitter release

40

What are neurotrophic factors secreted by glial cells involved in?

Development
Survival

41

What is the role of glia in neurodegenerative diseases?

Loss of neuroprotective factors
Toxic insult

42

What complicates the rational approach to identifying transmitter levels in disease

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

Decks in MD1 Neuroscience Class (55):