Postsynaptic compartment Flashcards
role of spines
increase surface area to optimise packing of many spines
serve as a separate electrical unit that modulates synaptic signals
provides a biochemical compartment that restricts mobility of molecules (resistor)
when do spines occur
1-10 per um of dendrite
synapse diversity
spines are heterogenous and have a lot of diversity
bigger response = greater density of spines
what is a spine neck
resistor for chemical signals
high resistance = massive response low resistance = stubby effect
increased width = decreased resistance
decreased length = decreased resistance
neck resistance formula
pL/A
L = length of neck
A = cross sectional area
p = resistance of cytoplasm
role of spine necks
filter synaptic events (plastic)
long necks = smaller response (amplitude)
role of postsynaptic spines
isolate chemical and electrical events
what is the main scaffolding protein
PSD-95
types of spines
filopodia
stubby
thin
mushroom
primary scaffolding of the excitatory synapse
contains PDZ domains
interact with gluR’s
central distribution and close to PSD
secondary scaffolding of excitatory synapses
lack PDZ domain
interact with primary scaffolding
types of ionotropic channels and receptors
nAChR
glutamate-gated
ATP-gated
voltage-gated
inward rectifying
open rectifying
how does the nAChR open
via twisting
3 states of ionotropic glutamate receptors
closed
open
desensitised
NMDA receptor
allows Na+ and Ca2+ through
K+ out
slower than AMPAR
sensitive to Mg2+ block (coincidence detector) which induces plasticity
