COGS 17 Lecture Notes - Lecture 5: Porosome, Synaptic Vesicle, Neuroglia
19 May 2018
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Lec 3B - Neural Functioning
● The synapse
○ Release of neurotransmitter → travelling to next neuron in pathway
● Presynaptic neuron
○ Sending neurotransmitter
● Post-synaptic neuron
○ Receiving neurotransmitter
○ Dendrites, cell body, receptor sites
● Synaptic cleft
○ Space between presynaptic and postsynaptic neuron
● Exocytosis
○ Release of neurotransmitter out of presynaptic cell
○ Vesicle - double lipid membrane
■ Filled with neurotransmitter
■ Energy requiring process
○ Synaptic vesicle
■ Cluster of protein molecules in membrane of synaptic vesicle
● Entry of calcium opens fusion pore→ after this step,
becomes a passive process ( no longer energy
requiring)
● Fusion pore widens, membrane of synaptic vesicle
fuses with presynaptic membrane
● Molecules of neurotransmitter being to leave terminal
button
● Functions of various proteins embedded in neuron membranes: ion gates,
fusion pores, receptor sites * each is specialised for only one function *
● The synapse
○ Once neurotransmitter gets released from fusion pore of presynaptic
cell, (e.g GABA),receptor sites built into the postsynaptic cell are
attracted to the NT where it fits
○ NT is released into synaptic cleft where it floats around until it chances
to bump against a receptor site that it fits
○ How the receptor sites react depend on the type of ions that are
flowing in the synaptic cleft and what kind of glial cells there are, as
well as what shape the receptor site is, and the quantity of enzymes in
the cleft
○ When NT attaches to receptor site, the ion gate opens
○ Excitation: Adding positively charged Na+ decreases polarity of post-
synaptic cell, bringing it closer to its threshold for firing
■ EPSP: excitatory postsynaptic potential - postsynaptic cell is
HYPOpolarized (go from more polarized to less polarized)-->
in the case of AcH
○ Gaba
■ Inhibition: Adding negatively charged Cl- increases polarity of
post synaptic cell, pushing it farther from its threshold for firing
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Document Summary
Release of neurotransmitter travelling to next neuron in pathway. Release of neurotransmitter out of presynaptic cell. Cluster of protein molecules in membrane of synaptic vesicle. Entry of calcium opens fusion pore after this step, becomes a passive process ( no longer energy requiring) Fusion pore widens, membrane of synaptic vesicle fuses with presynaptic membrane. Molecules of neurotransmitter being to leave terminal button. Functions of various proteins embedded in neuron membranes: ion gates, fusion pores, receptor sites * each is specialised for only one function * Once neurotransmitter gets released from fusion pore of presynaptic cell, (e. g gaba),receptor sites built into the postsynaptic cell are attracted to the nt where it fits. Nt is released into synaptic cleft where it floats around until it chances to bump against a receptor site that it fits. When nt attaches to receptor site, the ion gate opens.
