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Neuro Ch 5
Intro to Neuroscience
15
Medical
Undergraduate 2
08/01/2009

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Term
Electrical Synapses
Definition
Allow the direct transfer of ionic current from one cell to the next.

Occur at specialized sites called gap junctions.
Term
Postsynaptic Potential (PSP)
Definition
Electrical porential generated in the postsynaptic neuron in a gap junction.

Very small (1 mV), so often many will occur at once to continue the action portential.
Term
Chemical Synapse
Definition
Synapses that incorporate neurotransmitters in order to cause an action potential.

Most common form of synaptic transmission in the human nervous system.
Term
Synaptic Vesicles
Definition
Membrane enclosed spheres in the pre-synaptic element that contain neurotransmitters.

50 nm in diameter.
Term
Secretory Granules
Definition
Contain soluble protein that appears dark under an electron microscope.

Are large synaptic vesicles.
Term
Active Zones
Definition
Sites of neurotransmitter release.

Located on the intracellular ace of the membrane, jutting out into the cytoplasm.
Term
POstsynaptic Density
Definition
Protein accumulated in and just under the postsynaptic membrane.

Contains neurotransmitter receptors which convert intercellular chemical signals into into intercellular signal: change in membran potential or chemical change.
Term
Neuromuscular Junction
Definition
Chemical synaps between motor neurons from the spinal cord and skeletal muscle.
Term
Amino Acids at Most CNS Synapses for fast transmissions.
Definition
Glutomate (Glu)

Gamma-Aminobutyric Acid (GABA)

Glycine (Gly)

Acetycholine (Ach) - fast transmission at all neuromuscular junctions.
Term
Transporters
Definition
Special proteins embedded in vesicle membrane.

Responsible for concentrating neurotransmitters inside the vesicles.
Term
Neurotransmitter Release
Definition
Triggered by the arrival of an action potential in the axon terminal.

Depoarication of terminal membrane causes voltage-gated calcium channels in active zone to open.
Term
Exocytosis
Definition
The process in which veicles release their contents.

The membrance of the vesicle fuses to the presynaptic membrane at the active zone, allowing the contents to spill out into the synaptic cleft.
Term
Endocytosis
Definition
The process where the vesicle membrane is recovered, allowing the vesicle to be recycled.
Term
Transmitter-gated ion channels
Definition
Receptors that are membrane spanning proteins consisting of 4 or 5 sub units.

Pore is usually closed in the absence of neurotransmitters.

When neurotransmitters bind to the extracellular region of the channel, the pore opens allowing ions to flow through.
Term
Excitatory Postsynaptic Potential (EPSP)
Definition
A transient postsynaptic membrane depolarization caused by the presynaptic release of neurotransmitters.

Synaptic activation of Ach-gated and Glu-gated ion channels causes EPSP, for example.
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