neuron function part 4 Flashcards
What are gap junction?
specialized protein complexes that create an aqueous pore between adjacent cells
move ions between cells
changes in membrane potential
the quality of vesicle exocytosis is correlated with what?
strongly correlated with quantal transmitter released
what does the influx of ca trigger?
transmitter release through vesicle fusion
What is synaptotagmin?
A protein found tn membrane synaptic vesicles, binds to calcium at concentrations similar to those triggering vesicle fusion
When ca changes the chemical properties of synaptotagmin it allows what?
allows the protein to bind to SNARE proteins, syntaxin and SNAP-25, bringing the two membranes closer then fusion
what do inhibitory NT’s do?
Cause hyperpolarization of membrane
IPSP
makes postsynaptic cell less likely to generate AP
What does a excitatory NT do?
causes depolarization to membrane
EPSP
makes presynaptic cell more likely to generate AP
Ligand gated ion channels:
Glutamate receptors cause what?
Depolarization
Ligand gated ion channels:
GABA receptos and glycine receptors cause what>
Hyperpolarization
Ligand gated ion channels:
Nicotinic acetylcholine receptors cause what?
Depolarization
5-HT3, P2x receptors cause what?
depolarization
What are characteristics of G protein coupled receptors? (6)
Metabotropic receptors
receptors change shape
formation of second messanger
alters opening of ion channel
slow
may lead to long term changes via other cellular functions
Integration of postsynaptic potentials:
What is spatial summation?
Posysynaptic potentials from different sites infulence the net change in membrane potential
Integration of postsynaptic potentials:
Temporal summation
postsynaptic potentials that occur at slightly different times influence net charge in membrane potential
Strength of synaptic transmission:
response of postsynaptic cell is influenced by what?
amount of NT’s in synapse and number of receptors
rate of release/removal
Strength of synaptic transmission:
rate of release/removal
determined by frequency of AP’s
removal determined by
- passive diffusion out of synapse
- degradation by synaptic enzymes
- uptake by surrounding cells
number of receptors
-density of receptors on posysynaptic cell
Nicotinic Acetylcholine Receptors:
how many ligands required to open?
2
Nicotinic Acetylcholine Receptors:
what do the cation channels do?
Fluxes na, ca, K
Nicotinic Acetylcholine Receptors:
what are 4chara cteristics?
- reversal potential close to 0Mv
excitatory- depolarizes the membrane potential
goes from resting (closed) to activated (open) to desensitized (closed) state
Nicotinic Acetylcholine Receptors:
what hydrolyses ACH to make response brief?
acetylcholinesterase
Ionotropic Glutamate Receptors:
What do AMPA and Kainate require to open?
Glutamate binding to open - Flux Na, K
Ionotropic Glutamate Receptors:
What do NMDA receptors require?
Membrane depolarization to relieve Mg2 block and Glutamate and glycine to open
Ionotropic Glutamate Receptors:
Flux what?
na, K and Ca
NMDA highly ca permeable
reversal potentiall of glutamate close to 0
activation depolarizes the membrane potential
excitatory
Ionotropic Glutamate Receptors:
what clears glutamate from synaptic cleft?
glutamate transporters
GABA
receptors:
cause an influx of what?
influx of CL
GABA
receptors:
similar structure to what>
nicotinic receptors- pentameric
GABA
receptors:
what is the reversal potential>
Nerst potential of Cl -99mV
GABA
receptors:
Activity does what>
hyperpolarizes the membrane potential
GABA
receptors:
its effect on PSP
inhibitory
GABA
receptors:
what Clears GABA from Synaptic cleft?
GABA transporters
