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BIPN%20100%20Midterm%201%20Review%20Session%20Outline -...

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BIPN Midterm 1 Review Session Outline I. Post-synaptic events a. Two types of receptors: Ionotrophic vs. metabotrophic a. Ionotrophic : ligand gated ion channels i. Ion channel Receptor elicits a fast synaptic potential because it is quick and it lasts a short time 1. This always opens ion channels b. Metabotrophic : g-protein coupled receptors that exert actions through second messenger systems i. G-protein coupled receptors elicit slow synaptic potentials because the second messenger system through which it acts is slower but the response lasts longer. 1. Second messengers can open of close ion channels c. G-protein: have slow acting intrinsic GTPase activity meaning that when GTP binds to it and eventually GTP is hydrolyzed to GDP which turns off the switch. d. The complex is made up of the alpha, beta, and gamma subunits. Alpha unit has the GTP binding site and GTPase activity. 2. Signal OFF: GDP bound a. In the absence of NT b. Alpha is bound to the inhibiting beta and gamma subunits 3. Signal ON: GDP leaves, GTP binds a. Alpha subunit is dissociated from the inhibiting beta and gamma subunits b. Pathway: i. binding of the NT changes the conformation of the receptor ii. G-protein is active, releases GDP and binds GTP iii. Dissociation of subunits can allow binding to and activation of a regulatory membrane protein such as Adenylate Cyclase. iv. Activates second messengers: cAMP, Ca++, DAG, IP3 v. Activate protein kinases which will either activate or deactivate them vi. Products result from this and can result in modification of the cell
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1. ion channels could stay open more, maybe more channels are inserted. 2. alters ion concentration coming and going into and out of the cell vii. Turn off of the signal: 1. G α hydrolyzes GTP to GDP + P i (GTPase). The presence of GDP on G α causes it to rebind to the inhibitory βγ complex. So now it is inactivated *Here I dew the picture of the G-protein complex and its participation in the second messenger pathway. b. ESPS vs. IPSP i. After the release of NT from the axon terminal of the presynaptic cell… ii. Molecules diffuse across the gap and bind to receptors of the postsynaptic cell and a response in that cell is initiated. One of two responses can result 1. EPSP : if the synaptic potential is depolarizing and makes the cell more likely to fire an action potential 2. IPSP : if the synaptic potential is hyperpolarizing and moves the membrane potential farther from threshold and makes the cell less likely to fire an action potential. II.
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BIPN%20100%20Midterm%201%20Review%20Session%20Outline -...

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