L2. ionotropic and metabotropic channels Flashcards
what are ionotropic channels
receptors where it responds to ligand binding by opening up the pore for ion influc
where are ionotropic channels found
NMJ
eg of iono R
ACh nicotinic Rs
what are excitatory neuronal synapses
generates EPSP
what NT does sensory fibers release in stretch reflex
Gglutamate
what Nt does interneurons release in a reflex
GABA
what Nt does motor neurons release
ACh
2 types of Glu iono receptors
NMDA
NON NMDA
features of both NMDA and non NMDA
-both cation channels and have GLu open up the channel
properties of NMDA channels only
permeable to Ca - important for signalling
- channel blocked by Mg ion so Glu cant bind
what are meta R
membrane receptor that initiates a number of metabolic steps to modulate cell activity
structure of meta R
7 transmembrane alpha helicases structure
what activates meta R
NTs
what is coupled tp meta R
g proteins
is there ion channel with meta R
no
is it slow or fast response in meta r
slow
what effects does meta r have
indirect effects on channels and receptors
what NTs can bind to meta r and what are the effects
glu - memory, anxiety
ach - regulates EPSP in gangelions
serotonin
dopamine - motor control
what happens to cAMP signals when Gi coupled r is activated
- reduces the signal
- inhibitory receptor
what happens to cAMP signals when Gs coupled r is activated
increase signal
-stimulatory receptor
hat happens to cAMP signals when Gq coupled r is activated
increase s IP3 and DAG levels and signals
two modes of action of meta r
indirect and direct
what does indirect mode do
act via second messenger like cAMP, PKA
what does direct mode do
-activates G proteins and its subunits interacts with target channels
three sites of action of meta r
presynaptic, postsynaptic and cell body
- to produce an AP
what happens to AP size in the cell body in regards to meta r
the meta R activation closes K channel
- less repolarisation so the AP becomes bigger
whats the length of EPSP in nicotininc r
fast EPSP to mediate Na influx
whats the length of EPSP in muscarinic r
slow epsp for few secs
