Synaptic tranmission (Sept 18) Flashcards
What are the three modes of synaptic transmission?
Vesicular
Non-vesicular
Retrograde Release
What is Non-Vesicular ATP release?
It is release of neurotransmitter that is not in vesicles. (but is still not permeable to the membrane, so leaves through ion channels). An example of this is release of ATP in taste buds.
Do taste cells have a direct neurological connection to the brain? If they do not how do they transmit an action potential?
No, binding of tastant’s to taste receptors leads to cutting of peptidylinositol by phospholipases. Which causes IP3 and DAG, IP3 causes release of intracellular calcium, which causes an pseudo-action potentials with VGSCs that causes VG(ATP)Cs to open which releases ATP into the synapse firing the post synaptic cell to fire a potential.
Why do motor end plats each have 100 - 300 synaptic vesicles?
To guarantee that they will always fire a potential.
Where was quantal exocytosis first discovered? Why?
At the neuromuscular junction. Because the prep is very hardy and the channel very consistant.
EPSP stands for what/is what?
Excitatory Post-Synaptic Potential. Depolarization of the cell (Na channels)
IPSP stands for what/is what?
Inhibitory Post-Synaptic Potential. Hyper polarization (Cl channels open).
What is a miniature end-plate potential?
MEPPs, are small depolarizations which result from the release of a single vesicle of neurotransmitter. at the neuromuscular junction.
What is an EPP?
End plate potential. It is an EPSP at the neuromuscular junction (it’s called this because of motor end plates)
What is a miniature excitatory post synaptic potential?
MEPSPs, are small depolarizations which result from the release of a single vesicle of neurotransmitter.
What is a... Agonist: Antagonist: -Competitive -Non-Competitive Inverse Agonist:
Agonist: ligand which activates a receptor
Antagonist: stops the receptor it binds to from being activated.
-Competitive: competes for binding site
-Non-Competitive: binds elsewhere
Inverse Agonist: Binds to receptor which is always in its active conformation to deactivate it
What is constitutive activity?
Continuous never ceasing activity.
What are the four possible fates of neurotransmitters?
Diffusion: diffuse out of synaptic cleft
Degradation: Broken down by enzymes (like achetylchoninesterase in the neuromuscular synapse.
Re-uptake: returned to the pre-synaptic cell, via specialized membrane transporter proteins.
Uptake: taken in by surrounding glial cells, via specialized transporter proteins
What type of specialized protein enables reuptake and uptake?
Membrane transporter proteins.
Could a neurotransmitter be excitatory at one synapse and inhibitory at another? How is this possible.
Yes. The neurotransmitter could be binding to a different type of transmitter at the other cell, one which allows influx of different type of ion than in the other cell.
I have a neurotransmitter which is causing an inhibitory at this synapse by opening Cl channels, might it be able to perform an excitatory response at a different synapse, opening let’s say Na?
Yes, neurotransmitters are non specific. Instead the response of the cell (which is dictated the types of receptors) is what matters.
What is the purpose and location of K+ leak channel?
Maintain resting potential, all animal cells.
What is the purpose and location of voltage gated Na+ channel?
Action potential, nerve cells.
What is the purpose and location of voltage gated K+ channel?
Return membrane to resting potential.
Is GAMA normally excitatory or inhibitory?
inhibitory. but it must be a cl- channel.
Ionotropic membrane proteins must contain?
An integral ion channel.
What 3 molecules are listed in the small molecules class of neurotransmitters?
ACh
ATP
NO (nitric oxide) (fat soluble)
What 4 molecules are listed in the small amines class of neurotransmitters?
Dopamine.
Serotonin
Epinephrine
Norepinephrine