rise to macrophages phagocytosis debris waste pathogens Oligodendrocytes

Rise to macrophages phagocytosis debris waste

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rise to macrophages phagocytosis – debris – waste – pathogens Oligodendrocytes myelinate axons in CNS provide structural organization of CNS
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4/25/19 10 Myelination: refers to the wrapping of axons with cell membrnae electrically insulates fibers increases rate of impulse conduction along axolemma results in nodes and internodes Schwann cells myelinate most all axons in PNS participate in repair
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4/25/19 11 Axons: Myelinated vs. Unmyelinated Satellite cells PNS located in ganglia regulate environment around PNS neurons – O 2 , CO 2 – nutrients – neurotransmitter
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4/25/19 12 Neural Response to Injuries Occurs in PNS only CNS Too m any axons Astrocytes produce dense scar tissue Growth inhibiting factors secreted by astrocytes Neurophysiology
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4/25/19 13 Transmembrane potential Resting Membrane Potential ion concentration differs in ECF compared to cytosol Cells have selectively permeable membranes Ion permeability of membrane varies
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4/25/19 14 Resting Membrane Potential Leak channels are present Always open More K leak channels than Na leak channels More proteins- inside cell - note: neg. charge Overall – negative charge exists just inside Active processes across the resting membrane: sodium-potassium pump Continuous operation pumps 3 Na ions out pumps 2 K ions in Helps maintain resting membrane potential Restores resting membrane potential after membrane disturbances
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4/25/19 15 Resting membrane potential is result of Higher permeability to K+ than Na+ More K leaks out than Na leaks in Sodium potassium exchange pump 3+ out / 2+ in Proteins inside The voltage difference of the resting membrane potential is -70 mV Sodium and Potassium concentrations in ECF and ICF Important for neural function ECF 140 mM 10 mM + ICF 4 mM 140mM - [Na + ] [K + ] charge
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4/25/19 16 Changes in transmembrane potential Change occurs when channels open allowing ions to move Active (Gated) channels Respond to stimuli Chemically gated Voltage gated Mechanically gated Chemically gated channels Respond to chemicals (neurotransmitters) On – Dendrites – Somas
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4/25/19 17 Mechanically gated channels Open when cell membrane is physically distorted Located in sensory receptors Changes in transmembrane potential opening of channels change in permeability two types of changes in potential graded potentials action potentials
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4/25/19 18 Graded potential What happens when channels open? Ions move Depolarization….which ion movement causes this? Hyperpolarization…which ion movement causes this?
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4/25/19 19 Graded potentials • On dendrites and somas • What channels are present here? Graded Potentials changes in potential dendrites/somas Can be depolarizing or hyperpolarizing… vary in strength… local Effect decreases w/ distance do not propagate
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4/25/19 20 Reminder of where we’ve been… and what’s next Action potentials Propagated disturbance in membrane potential
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  • Spring '18
  • Mark Bolke

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