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8 chemical synaptic transmission (step 1 (2 classes of neurotransmitters)…
8
chemical synaptic transmission
step 1
2 classes of neurotransmitters
large neuropeptides
are synthesised in the cell body of the neuron
& are transported to the synaptic terminal -thru the axon
smaller amines/amino acids
can generally be synth at the
-presynaptic terminal itself
step 2
neurotransmitter packaging
once synthesized,
they are packaged into vesicles
ready to be launched acoss
the synaptic cleft
these vesicles are released
when they receive order frn Ca2+ ions
to do so
step 3
neurotransmitter release
when electrical signal reaches the presyn terminal
it opens voltage gated Ca2+ channels
in the membrane
Ca2+ ions frm EC environment rush into
the presynaptic terminal
these Ca2+ ions encounters the vesicles
-& causes them to fuse with the membrane
of presyn terminal at the synaptic cleft
as they fuse & open,
-the neurotransmitters are expelled
into the synaptic cleft
step 4
neurotransmitter binding
the NTransm now diffuse thru the synaptic cleft
until they reach the postsynaptic neuron
the memb of the postsyn neuron contain
channels(receptors) that control
how a neurotransmitter can be
translated into an electrical signal
step 5
stopping the chemical signal
once the signal has been translated,
into an electrical signal
the postsynaptic receptors need to be
cleared v quickly
-so that they can recieve transmitters
frm new signals
this can be done by
degrading of neurotransmitters
neurotransmitters being transported
back into the presynaptic
terminal to be recycled
sometimes they are absorbed
by the postsynaptic terminal