Lecture 3 - Nervous System

Barrier surrounds the vessels in the brain 7 neuronal

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Unformatted text preview: body –  Axon  ­ conducts ac4on poten4al away from cell body –  Axon terminal  ­ synapse (gap of 20 nm wide) •  Neurons connect with some neurons but not others – connec4on specificity •  Informa4on travels in only one direc4on 6 Glial cells •  Do not produce ac4on poten4al •  Support neurons physically, immunologically and metabolically –  Myelin  ­ Insula4on of Schwann cells (or oligodendrocytes) •  Mul4ple sclerosis – decreased func4on of ac4on poten4al –  Astrocytes – blood ­brain barrier, surrounds the vessels in the brain 7 Neuronal connec4ons •  Neurons are linked through an organize network of connec4ons •  Neurons with fewer dendrites process fewer inputs 8 Neuronal connec4ons •  Labeled each neuron with a different color –”brainbow” mouse, Lichtman Nature 2007 9 How neurons respond to s4muli? •  Genera4on of ac4on poten4al •  Electrical signals allow neurons to communicate with each other rapidly (150 m/sec) and over long distances What is membrane poten4al? 10 Membrane poten4al •  Ions cannot cross cell membrane •  Ions will only cross plasma membrane through selec4ve gated channels (ac4ve/passive transport) 11 Membrane poten4al – ar4ficial cell Cl ­ Cl ­ Cl ­ Cl ­ Cl ­ Na+ Cl ­ Na+ Na+ Na+ + Na+ Na Outside Na+ Cl ­ Cl ­ Cl ­  ­ Cl Cl ­ Na+ Na+ + Na+ Na Na+ Outside Membrane poten4al ≠ 0 (+) Membrane poten4al = 0 Na+ Na+ Cl ­ Inside Inside Cl ­ Na+ Cl ­ No ion channels Na+ Na+ Na+ Cl ­ Cl ­ Cl ­ Na+ ­Selec7ve leak channel 12 Membrane poten4al •  If a selec4ve ion channel is open, ions will move across the membrane following its electrochemical gradient hOp://isites.harvard.edu/fs/docs/icb.topic1117507.files/membrane_poten4al.mpg 13 Res4ng poten4al •  Membrane poten4al when the cell is at rest (neuron  ­70 mV) 14 Genera4on of membrane poten4al What contributes to the main...
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