Neurotransmission Flashcards
What are some criteria to classify neurotransmitters?
The presynaptic cell contains the chemical and the mechanism to make it
There is a mechanism for inactivating the chemical
The chemical is released from the axon terminal when neuron is stimulated
Receptors for chemical are present on postsynaptic cells
What is the monoamine synthesis of epinephrine?
Tyrosine to dopa to dopamine to norepinephrine to epinephrine
What is the monoamine synthesis of serotonin?
Tryptophan to 5-hydroxytryptophan to serotonin
What are the enzymes involved in the monoamine synthesis of epinephrine?
Tyrosine hydroxylase
Aromatic amino acid decarboxylase
Dopamine beta-hydroxylase
Phenylethanoamine N-methyltransferase
What are the enzymes involved in the monoamine synthesis of serotonin?
Tryptophan hydroxylase Aromatic amino acid decarboxylase
How is glutamate made?
Using glutamate synthase from glutamine or the citric acid cycle
How is GABA made?
Using glutamate decarboxylase from glutamate
How is glutamate recycled?
GABA is made into succinate semialdehyde using 4-aminobutyrate transaminase
Succinate semialdehyde enters the CAC by succinate semialdehyde dehydrogenase
The CAC uses glutamate synthase to make glutamate
How is acetylcholine made?
Choline acyltransferase uses AcetylCoA to and choline to make acetylcholine
What is a classical neurotransmitter?
In punctated
Release the impulse for each AP
Synthesized in the cytoplasm and Golgi apparatus of terminals
Released into synaptic cleft with depolarization of axon terminal
How do monoamines work?
Vesicles stuffed with precursor amino acid and synthesizing enzymes en route to terminal
How are neuropeptides synthesized?
Gene transcription and translation into amino acid chains that can act as signalling molecules
What do peptide neurotransmitters do?
Release gradually in response to increases in AP
Has widespread effects as they are released into ECF, ventricles, or bloodstream as an undirected synapse
Act as neuromodulators
Where are peptide neurotransmitters synthesized?
In the cell body, processed and packaged into Golgi into large vesicles and then transported to the terminal
Can take a long time to replenish the releasable pool in the terminal
What are neurotransmitters packaged into?
Secretory vesicles
How are neurotransmitters packaged?
Proteins are synthesized in the RER and transported to the golgi
Bud off golgi to form the vesicle with the propeptide and proteolytic enzymes
Transporter proteins actively pump neurotransmitters into vesicles
What are small clear core vesicles?
Contain classical NT
40-60 nm diameter
What are large dense-core vesicles?
Contain monoamine and neuropeptides
90-250 nm diameter
Why might you not be able to find large vesicles?
Because the neuropeptides have been depleted and waiting for replenishment
What does the coexistence of neurotransmitters refer to?
More than one type of neurotransmitter is synthesized and released in a neuron
-a mix of classical and neuropeptide
How are neurotransmitters transported to the axon terminal?
Anterograde to the axon terminal by motor proteins like kinesin
Requires energy
What are the steps of neurotransmitter release?
- AP in the axon terminal
- Open voltage-gated Ca2+ channels
- Increase calcium influx
- Activates proteins responsible for mobilizing vesicles and fusing vesicles with synaptic membrane
- Vesicles move to the active zone
- Vesicles dock onto the synaptic membrane
- Fuse with synaptic membrane and release NTs into the cleft
What happens when neurotransmitters are in the synapse?
They bind to receptors
Receptors are:
Specific for neurotransmitter
