lecture 4 Flashcards
why do voltage gated ion channels open
they respond to changes in electrical potential
why do transmitter gated ion channels open
repsond to specific neurotransmitters
two types of receptors
inotropic
metabotropic
inotropic
receptors open the channels directly
metabotropic
receptors open it indirectly
not attached to protein- responds to neurotransmitter which activates secondary messengers which ope the channels
key lock principle
all ion channels in the post synaptic membrane are transmitter gated - only fit into specific receptor types
excitation
positive ions ENTER = depolarisation
more likely that an AP will be triggered at the axon hillock
threshold reached
inhibition
negative ions ENTER - hyper polarisation
less likely that an AP will be triggered= does not reach threshold
for an AP to be triggered membrane potential
at axon hillock must DEPOLARISE beyond -50mv
generator potential
single post synaptic is insufficient to trigger new AP - must past threshold
so GP integrates/sums changes caused by several AP’s at one post synaptic neutron
spatial summation
multiple presynaptic neurons together release enough neurotransmitters to exceed threshold
temporal summation
one presynaptic neutron releases neurotransmitters many times
combines neurons accuring in rapid succession
neurotransmitter removal
neurotransmitter degradation and reuptake
to stop neurotransmitter activity
it has to be actively removed to stop their influence on post synaptic cell
degradation
special enzymes in the synaptic cleft break down NT’S
components are recycled to make new NT’S
