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Intra- neuronal Transmission (Electrical) PowerPoint Presentation
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Intra- neuronal Transmission (Electrical)

Intra- neuronal Transmission (Electrical)

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Intra- neuronal Transmission (Electrical)

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  1. 0 Intra-neuronal Transmission (Electrical)

  2. What do you really needto know here? The RMP is -70 mV, meaning that the cell is more negative inside than outside, And... That means that it is polarized, or ready and waiting to produce a neural signal.

  3. A neural signal is a(n) _______ phenomenon, as it travels along the length of a single neuron. • chemical • supernatural • enigmatic • electrical 4

  4. 0 What happens when the cell is NOT at rest? The Action Potential: -takes place at the axon where there are special Na+ channels -allows neural signals to travel long distances in the body And, all action potentials take this form…..

  5. 0 How The Action Potential Occurs Depolarization (Na+ channels open & Na+ enters cell) Polarization (positive ions pumped out of cell) mV threshold all-or-nothing phenomenon travels long distances, but it’s SLOW “Overshoots” hyperpolarization with absolute and relative refractory periods)

  6. If all action potentials take this form, then how is the Intensity of a stimulus encoded (e.g., the brightness of a light, the loudness of a sound)??????????????????????? 0 By means of its temporal characteristics… Or, its Rate of firing!!!

  7. 0 But, how do neurons encode the Type of stimulus(e.g., whether it is a light, a sound, a touch)??????????????????????? By means of… the specific nerve tract stimulated!!!

  8. 0 Action potentials w/ refractory periods – approx. 1 msec Therefore, approx. 1000 impulses per second… VERY SLOW!!! myelin sheathe (white fatty tissue) Action potentials occur At the nodes of Ranvier Multiple sclerosis involves the degeneration of the myelin sheathe nodes of Ranvier (bare sections of axon)