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Definition
Connections to adjacent cells through gap junctions
•Two neurons linked together by gap junctions
•Some are between neurons and glial cells
•Adjacent cells are connected by gap junctions such that when an electrical signal is generated in one cell it is directly transferred to the adjacent cell.
•Second messengers can also move through these junctions
•Functions in the nervous system:
–Rapid communication
–Ions or second messengers
–Usually bidirectional communication
–Excitation and inhibition at the same synapse
–Identified in the retina, cortex, brainstem (breathing), and hypothalamus (neuroendocrine neurons) |
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Definition
Operate through the release of neurotransmitter
• Functional anatomy of chemical synapses
–Presynaptic neuron
–Postsynaptic neuron
–Synaptic cleft (30-50 nm wide)
–Unidirectional
–Usually synapse on dendrites (axodendritic)
–Some synapse on soma (axosomatic) or axons(axoaxonic) |
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| neuron that sends the signal |
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| neuron that recieves the signal |
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| The space between the pre and post synaptic neurons |
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0.5-5 msec between arrival of an action potential and change in postsynaptic Vm
–Caused by changes in [Ca2+] entry, vesicle docking, and release of neurotransmitter
–Not related to diffusion of neurotransmitter across the synaptic cleft |
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Definition
| The fast response occures whenever a neurotransmitter binds to a channel-linked receptor |
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| Slow responses, by contrast, are mediated through linked receptors |
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| •Change in membrane potential in response to receptor-neurotransmitter binding |
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•Excitatory postsynaptic potential (EPSP)
–Most common neurotransmitter: glutamate |
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•Inhibitory postsynaptic potential (IPSP)
–Most common neurotransmitter: GABA |
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–More likely to produce an action potential
–Depolarization |
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Definition
–Less likely to produce an action potential
–Hyperpolarization
–Membrane stabilization |
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