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22 Cards in this Set
- Front
- Back
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Define types of cellular communication
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Direct communication-
Connections mediated by released chemical substances- endocrine, paracrine, autocrine |
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Explain the basis for convergent neurotransmitter (NT) actions.
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-multiple inputs affect the same effect system
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Explain the basis for divergent neurotransmitter(NT) actions.
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-one NT activates more than one subtype to elicit more than one type of post-synaptic response
*diff receptors= diff response |
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Identify and describe the receptor types upon which the different neurotransmitters act.
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1. Ligand-gated ion channels= ionotropic= Nicotinic
-5 subunits -present at neuromuscular junction 2. G Protein-Coupled Receptors (GPRCs)= metabotropic= Muscarinic -M1-M5 subtypes -differential distribution -differential functions |
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Identify and describe the Ionotropic receptor subtypes upon which the different neurotransmitters act.
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Nicotinic:
-NAchRs= pentameric ligand-gated ion channel allows cell to be permeable to Na+ & Ca2+ located at skeletal neuromuscular jxns, autonomic ganglia, adrenal medulla & in CNS Ligand-gated: -nitoctinic Acetylcholine (Na+) -serotonin (Na+, K+) -NMDA, AMPA, & Kainate (glutamate) (Ca2+) -GABA (Cl-) |
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Identify and describe the Metabotropic receptor subtypes upon which the different neurotransmitters act.
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GPCR:
-coupled to G proteins -signal transducer |
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There are both muscarinic/metabotropic & nicotinic/ionotropic cholinergic receptors. Why are they called cholinergic receptors?
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The are for acetylcholine (ACh)
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What is the consequence of GABA at pentameric ligand-gated channel (NAchRs)?
glutamate? |
depolarization (GABA)
fast depolarization (glutamate) |
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What are pentameric ligand-gated ion channels blocked by?
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d-tubocurarine
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(metabotropic/ionotropic) receptors indirectly alter ion conductance & neuron excitability
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metabotropic
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define autoreceptor & how it decreases NT release
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-receptors on prejunctional membranes for NE, NPY & ATP feedback (alpha-2)
inhibits AC & NT synthesis |
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define heteroreceptor & how it decreases NT release
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-inhibition of sympathetic neurons may also be caused by M2 & M4 muscarinic, serotonin, histamine, & dopamine receptors
inhibits AC & NT synthesis |
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Describe the signaling mechanism of tyrosine kinase and hormone receptors (nuclear receptors)
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Phosphorylation within a specific motif on a protein promotes the formation of a scaffolded signaling pathway, and helps to activate and/or localize proteins.
RTKs typically stimulate cell growth and mitosis. |
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Describe processes for receptor regulation: upregulation
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-more receptors?
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Describe processes for receptor regulation: downregulation
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-recycling of receptor back to membrane or degradation of receptor in lysosomal system
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Describe processes for receptor regulation: desensitization
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-may be a rapid inhibitory effect resulting from phosphorylation or internalization of receptor
-chronic exposure may lead to long-term decrease in responsiveness resulting for receptor down-regulation (degradation) |
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Describe processes for receptor regulation: denervation supersensitivity
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-increased response following increased receptor synthesis
-adaptive response resulting from receptor blockade or decreased release of endogenous ligand from pre-synaptic neuron |
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Describe the role of protein phosphorylation in the regulation of synaptic transmission.
Receptor Sensitivity (e.g., beta-adrenergic receptor desensitization, odorant rec.) |
-can inactivate (desensitize ion receptors)
-alter function of ion channels: open/close more readily & insert into membrane |
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Describe the role of protein phosphorylation in the regulation of synaptic transmission.
Receptor Trafficking (e.g., AMPA receptor) |
-phosphorylation (by PKa or CaMKII) leads to insertion of AMPA receptor in the membrane
-phosphorylation increases activity HFS---> LTP -dephosphorylation decreases synaptic strength LFS---> LTD |
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Describe the role of protein phosphorylation in the regulation of synaptic transmission.
Protein Transcription |
-phosphorylation can activate/inactivate enzymes involved in the synthesis of NT
(& in glucose metabolism) |
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Physiological actions of ionotropic receptors
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influence synaptic transmission at neuromuscular jxns
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Physiological action of metabotropic receptors
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-activation of CREB (cAMP response element binding protein) alters gene expression
-leads to changes in neural function |
