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Unformatted text preview: BIPN 100 –Dr. Fortes TA Jing Wang Handout 2 [email protected] OH Wed 4-5 @ Café Roma 1. Myelin/Glial Cells A. Insulate axon MB to prevent leakage of ions – no channels inserted where myelin is B. Allow faster conduction velocity of AP C. Reduces requirement to maintain conc. gradients under myelin (not at nodes), which saves a lot of ATP D. CNS: oligodendroglia myelinate several axons E. PNS: many Schwann cells myelinate a single axon by wrapping around it and leaving space between each other F. Glial cells – non-excitatory neuronal cells used to support excitable neurons i. Epindymal cells: line cavities of the CNS, secrete cerebrospinal fluid (CSF) ii. Microglia: act like immune cells iii. Astrocytes: participate in uptake of K+ and certain NT’s, form part of the blood-brain barrier (BBB) 2. Synaptic Transmission A. Electrical Synapses – electrical signal (current) passes directly from one cell to the next via gap junctions i. Gap junctions – connect the cytosol of two adjacent cells through a channel ii. Regulation of a system as a whole instead of individual neurons B. Chemical Synapses – Synapse that uses NT’s/hormones to communicate with target cell C. Pre-Synaptic events – Release of NT (fig 8.20) i. NT can be excitatory or inhibitory to the target cell (a) AP reaches axon terminal depolarization opens V-G Ca++ ch. (b) Ca++ flowing in bind regulatory proteins (c) Synaptic vesicles release NT via exocytosis D. Post-Synaptic Events – NT diffuses across synaptic cleft, binds its receptor (fif 8.22) i. Fast response - Receptor is a Ligand-Gated ion channel conformational change opens channel ii. Slow response - Receptor is a G-protein coupled receptor (GCPR) 2 nd messengers used to transmit signal E. Removal of NT-signal transmission i. Removal by Reuptake – Nt’s get taken back up by the neurons/vesicles that released them...
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- Winter '07
- NMDA, main inhibitory NT