7 - Neurotransmission Flashcards
What is neurotransmission?
Information transfer across the synapse requires release of neurotransmitters and their interaction with postsynaptic receptors
How does synaptic transmission work? (simple)
- Transmission released from first cell
- Synaptic activation of second cell
- Signal integration and signal conduction by second cell.
What are spines?
Protrusions from dendrites to increase input
What is the soma?
The cell body
How small is the gap in the synapse?
20-100nm
How small is the gap in the synapse?
20-100nm
What are the 3 stages of synaptic transmission?
- Biosynthesis, packaging and release of neurotransmitter
- Receptor action
- Inactivation
Features of neurotransmitters
- Very diverse
- Amino acids, amines & neuropeptides
- ## Rapid
Give 3 examples of amino acid neurotransmitters
Glutamate (exitatory)
Gamma amino butyric acid (GABA)
Glycine
Give 3 examples of amine neurotransmitters
Noradrenaline (NA)
Dopamine (DA)
Acetyl choline
Give an example of a neuropeptide neurotransmitter.
Opioid peptides
Activation of a CNS synapse
- AP reaches terminal - depolarisation
- Sodium enters so +ve membrane
- Outflow of potassium
- Triggers calcium entry
- Neurotransmitters released from vesicle into gap
- Transmitter is removed from gap via a transporter back into presynaptic side
What is electro-mechanical transduction?
The change from when calcium enters to when transmitters are released
What are presynaptic membrane proteins and what do they do?
Interactions between proteins in the vesicles and proteins in the active zone allows vesicles to fuse. Vesicles with proteins are said to be ‘primed’
Proteins have an a-helix tail which can connect together
What does calcium entry trigger?
It activates the calcium sensor in the protein complex which causes a conformational change in the vesicle complex promoting fusion with membrane and release of neurotransmitter. (Exocytosis)
What do neurotoxins target in the synapse?
Vesicular proteins
Examples of neurotoxins
Slide 14
Summary - what 3 things does transmitter release require?
- Transmitter containing vesicles to be docked on the presynaptic membrane
- Protein complex formation between vesicle, membrane and cytoplasmic proteins to enable both vesicle docking and a rapid response to Ca2+ entry leading to membrane fusion and exocytosis.
- ATP and vesicle recycling
What different types of receptors are there?
Ion channel receptors
G-protein coupled receptor
How do ion channel receptors work? How fast are they?
Transmitter binds to complex causing conformational change and a channel opens
Very fast
How do G-protein coupled receptors work? How fast are they?
Receptor is linked to G-protein linked to an effector.
Effector can be enzymes or channels
