Synaptic transmission Flashcards
Describe the synaptic neuron
Axon terminal with postsynaptic membrane. Vesicles filled with neurotransmitter. Ca2+ move from extracellular fluid to neuron
What are the charges inside and outside of the neuron?
Inside = more negative, outside = less negative
What are vesicles?
Double layer of phosphate group
What do voltage-gated ion channels respond to?
Open in response to changes in membrane potential
What do transmitter-gated ion channels respond to?
Open in response to neurotransmitter molecule binding with receptor site
What determines whether synapse is excitatory or inhibitory?
The type of neuron released
Explain process at presynaptic membrane (5)
Action potential arrives and Ca2+ channels open. Ca2+ enter axon terminal + vesicles fuses with presynaptic membrane. Neurotransmitter released to synaptic cleft
What happens at the postsynaptic neuron? (5)
Neurotransmitter bind with ion channels at receptor site, ion channels open and ions enter postsynaptic neuron. Generates postsynaptic potential and neurotransmitter removed from receptor site. Channels close.
What is postsynaptic summation?
Single PSP is insufficient for action potential, so generator potential build up is slow & graded. GP integrates changes caused by multiple action potentials
What are the 2 types of neurotransmitter removal?
Degradation (enzymes break them down, partly recycled) and reuptake (pre-synaptic axon takes up NT’s + returns to pre-synaptic cell)
State the 2 forms of transmitter-gated channels
Ionotropic (open directly) and metabotropic (open indirectly)
Which channel opens depends on what? (2)
The NT has been released and receptor site and G-protein (produces chemical as 2nd messenger)
What is the 1st messenger?
Neurotransmitter
Describe temporal summation
Combination of PSP’s occurring in rapid succession together
Define spatial summation
Combination of PSP’s occurring together in close temporal proximity at different synapses of same postsynaptic neuron
