Flashcards in CNS Transmission Deck (42):
What are the sensory inputs?
What is an action potential?
Electrical signal along nerve
What is a neurotransmitter?
Chemical signal at nerve ending
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
What is the main pre-ganglionic autonomic neurotransmitter and receptor?
What is the main sympathetic neurotransmitter and receptor?
a- and b-adrenoceptors
What is the main parasympathetic neurotransmitter and receptor?
What is the main somatic neurotransmitter and receptor?
What are the requirements for chemical neurotransmission?
- Vesicular content
- Na and K ion channels
- Ca influx
How is noradrenaline inactivated at the synapse?
Neuronal uptake - predominant removal
Metabolism - very small contribution
What is the pre-junctional receptor for noradrenaline?
Can drugs with peripheral actions also have effects on the CNS?
Yes, and dramatic ones, too
But only if they cross the BBB
Describe the uptake of noradrenaline at the synapse
- High affinity
- Low affinity
What does cocaine do at the synapse?
Block neuronal uptake of NA
Increased response when nerves activated
Does cocaine have dose-response effects?
South American Indians chewed leaf
- Slow absorption
- Low concentration
- Relief from
- 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
What does amphetamine do at the synapse?
Displace noradrenaline from storage vesicles
- NA released even during low activity
Competes for uptake receptors
What are the functions associated with noradrenaline?
What are the catecholamines?
What type of chemical is serotonin?
What are the amino acid neurotransmitters?
What are the peptide neurotransmitters?
What is a gaseous neurotransmitter?
Which neurotransmitter, unlike others, is made on demand?
What is the distribution of neurotransmitters?
Others highly localised
Describe catecholamine synthesis
IC: Tyrosine hydroxylase > L-DOPA > doa decarboxylase > dopamine
Vesicle: Dopamine-b-hydroxylase > NA > phenyl-ethanolamine-N-methyl transferase > adrenaline
In which cells is adrenaline synthesised?
Adrenal chromaffin cells
Which nerves synthesises dopamine only?
Where are some areas of the brain to which noradrenergic pathways project?
Caudal raphe nuclei
Where are some areas of the brain to which dopaminergic pathways project?
What are some of the pathways in which dopamine is involved?
- Parkinson's: depletion of dopamine in basal ganglia
- Schizophrenia: changes in dopamine rich areas like:
- Frontal cortex
- Basal ganglia
- Temporal lobe
- Dopamine actions in nucleus accumbens and ventral tegmental area
- Prolactin secretion
- Chemoreceptor trigger zone outside BBB
- Less important
What neurotransmitter uptake does cocaine block?
What is cocaine's dopaminergic action linked to?
What type of channel does cocaine also block?
Happens at much higher concentrations
Can a synapse be excitatory AND inhibitory?
No, can only be one or the other
Can a neurotransmitter be excitatory AND inhibitory?
Yes, depending on which receptor is present
What type of receptor is a nicotinic receptor?
Ligand-gated ion channel
Na influx driven depolarisation
What type of receptor is a GABA A receptor?
Ligand-gated ion channel
Cl influx driven hyperpolarisation
What are post-synaptic receptors responsible for?
Action potential generation/modulation
What are pre-synpatic receptors responsible for?
What are neurotrophic factors secreted by glial cells involved in?
What is the role of glia in neurodegenerative diseases?
Loss of neuroprotective factors