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25 Cards in this Set
- Front
- Back
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How can axons of nerves in the peripheral nervous system differ from axons of nerves in the central nervous system?
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The axon of the cns nerves often have bifurcations and en passant (in passage) synapses.
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How are neurotransmitter vesicles in the pre-synaptic neuron 'loaded'?
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Neurotransmitter is pumped (ATP-Dependent*) from the cytosol into the vesicle.
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What type of membrane does the neurotransmitter vesicle have?
How is this membrane synthesized? |
It has a lipid bilayer.
It is produced by membrane recycling. |
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What is the presynaptic density made of?
Name 2 things that it does. |
Made from proteins.
1. It holds presynaptic vesicles in place at the synapse. 2. Prevents vesicles from fusing (therefore exocytosing) with the cell membrane. |
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What proteins are most important to know in the presynaptic density?
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1. Actin
2. Synapsin |
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What does the protein matrix in the synaptic cleft do?
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It keeps the pre- and post-synaptic densities aligned. This makes transmission much more efficient.
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What are some notable pre-synaptic structures?
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1. Pre-synaptic vesicles
2. Mitochondria 3. Pre-synaptic density 4. Ca channels |
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What are Ca channels?
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They are voltage gated and they are located (concentrated) in the region of the synapse.
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What is the specific name for Ca channels that are found at our synapses?
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N-type Ca channels.
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What poison can irreversibly block our N-type Ca channels?
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omega-Conotoxin.
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What do the Ca channels do?
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They open and close quickly when an action potential arrives.
This allows a 'squirt' of Ca ion to ENTER the neuron. |
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What is the link between the action potential and exocytosis?
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Ca ion entry.
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What does the post-synaptic density do?
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It is a protein structure that holds transmitter receptors and associated ion channels in the synaptic region.
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What are synapsin's and actin's respective roles in the presynaptic density?
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Actin is the larger protein, Synapsin anchors the vesicle to the Actin.
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This protein is bound by the incoming Ca ions and it then inactivates the Ca ion channel to prevent further Ca ions from entering the axon.
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Calcineurin.
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Ca ion, upon entry into the neuron bind to _____________ and this complex activates ________ ___________. This phosporylates ____________.
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Ca ion, upon entry into the neuron bind to Calmodulin and this complex activates CAM-Kinase II. This phosporylates Synapsin I.
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What are Quanta?
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The sporadic release of a single vesicle in the pre-synaptic neuron--because intra-cellular free Ca ions are present.
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What is 'washout'?
Where does it occur? |
Washout is when neurotransmitter diffuses out of the cleft and eventually into the blood without reaching a receptor.
Occurs in the PNS but the CNS has a Glia seal around the synapse so we don't see it there. |
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What are 3 ways in which a neurotransmission can be terminated?
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1. Washout
2. NT can be metabolized into a different structure. 3. NT can be pumped back into axon terminal (Na dependent High Affinity Reuptake) |
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The NT binds to a receptor on the post-synaptic neuron, but this is what brings about change in the neuron.
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The effector, which is usually an ligand-gated Ionophore (ion channel).
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What is an EPSP?
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Excitatory Post-Synaptic Potential.
Brings neuron closer to threshold. Depolorizes. Associated with Na and K--bringing them in. |
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What is an IPSP?
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Inhibitory Post-Synaptic Potential.
Takes neuron further from threshold. Hyperpolerizes. Associated with Cl--bringing it in. |
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What is Temporal Summation?
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Multiple Post-Synaptic Potentials from the same location.
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What is Spatial Summation?
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Multiple Post-Synaptic Potentials from different locations.
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Most EPSPs are generated on ___________, while IPSPs are concentrated on the ___________.
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Dendrites
Soma IPSPs must move a shorter distance, lose less charge, and negate several EPSPs. We whisper 'fire' but we shout 'no'. |
