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35 Cards in this Set
- Front
- Back
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metabotropic receptors
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7-transmembrane G-protein coupled; binding results in 2nd messengers that modulate volate-gated channels; can last seconds to minutes
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targets of metabotropic receptor action
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calcium (inhibit fxn presynaptically) and potassium (activate postsynaptically) channels
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presynaptic drug actions in CNS act on
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synthesis, storage, metabolism, and release of neurotransmitters
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reserpine
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depletes monoamine synapses of transmitter by interfering with intracellular storage
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amphetamine
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induces release of catecholamines from adrenergic synapses
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Capsaicin
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release of peptide substance P from sensory neurons
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tetanus toxin
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blocks release of transmitters
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cocaine
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blocks uptake of catecholamines (dopamine and norepi) at adrenergic synapses, thus potentiates action of these amines
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why doesn't cocaine affect acetylcholine
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degraded via enzymes, not by reuptake
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what do opioids mimic
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enkephalin
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endocannabinoids
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retrograde signaling
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noradrenergic cell bodies are found primarily where
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locus caeruleus in caudal pontine central gray matter; axons branch repeatedly and are extraorinarily divergent
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aa neurotransmitters
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glutamate, glycine, and GABA
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glutamate breakdown/recycling
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glia convert to glutamine which is released and taken up by nerve terminal and converted back to glutamate
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glutamate receptors
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AMPA (on all neurons), KA (hippocampus, cerebellum, and spinal cord), and NMDA (on almost all neurons); all have 4 subunits
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which glutamate receptos are highly permeable to Na+, K+, and Ca2+
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NMDA
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what glutamate receptors result in channel opening at resting membrane potential
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AMPA and KA (NMDA is voltage-dependent via extracellular Mg++ pore blockade)
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what results in long-term potentiation (LTP)
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rise in intracellular Ca2+ that accompanies channel opening causing long-lasting enhancement in synaptic strength; can last hours/days
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excitatory synapse receptors
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AMPA toward periphery and NMDA in center; KA unknown
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glycine receptors
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pentameric selectively permeable to Cl-; Strychnine selectively blocks and is a convulsant
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fast GABA receptor and fxn
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GABAa; selectively permeable to Cl-; inhibited by picrotoxin and bicuculline-generalized convulsants
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slow GABA receptor and fxn
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GABAb; metabotropic; activated by antispastic drup baclofen; either inhibit Ca2+ or activate K+=long-lasting and slow; located in perisynaptic region
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M2 acetylcholine subtyype receptor
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slow; opens potassium channels; only located in a few sites
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M1 receptor
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slow; more widespread; decreases membrane permeability to potassium; excitational
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pathways that contain acetylcholine
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neostriatum, medial septal nucleus, and reticular formation
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monoamines
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catecholamines and 5-hydroxytryptamine (serotonin)
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major dopamine pathways
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substantia nigra to neostriatum and ventral tegmental to limbic structures
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dopamine receptors
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all metabotropic; slow inhibitory action on CNS neurons
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D2 receptors
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opens K+ channels via G-coupling; substantia nigra
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most noradreneric neurons are where
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locus caeruleus or lateral tegmental area of reticular formation; most CNS receive diffuse input
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noradrenergic receptors
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metabotrophic; hyperpolarize by increasing K+ conductance (a2 receptors in locus caeruleus); enhances excitatory via direct/indirect (disinhibition, a1 or B) mechanisms
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serotonin pathways
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raphe or midline regions of pons and upper brainstem; in unmyelinated fiber that diffusely innervate most CNS
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serotonin receptors
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all but 5-HT3 metabotropic; most have strong inhibitory action (5-HT1a)
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regulatory fxns of 5-HT containing neurons
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sleep, temp, appetite, neuroendocrine
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what activates nitric oxide synthase (NOS)
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calcium-calmodulin; NMDA activation causes generation due to increase Ca2+
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