1 / 23

Neural Communication: Action Potential

Neural Communication: Action Potential. Lesson 10. Neural Signaling: Axon. Action Potentials propagated electrical signal regenerated Large & rapid changes in E m depolarization repolarization ~. Action Potentials. Electrically-gated channels or voltage-gated Characteristics

radha
Télécharger la présentation

Neural Communication: Action Potential

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NeuralCommunication: Action Potential Lesson 10

  2. Neural Signaling: Axon • Action Potentials • propagated electrical signal • regenerated • Large & rapid changes in Em • depolarization • repolarization ~

  3. Action Potentials • Electrically-gated channels • or voltage-gated • Characteristics • all-or-none • relatively slow • non-decremental ~

  4. Threshold of Excitation • also: threshold potential • Triggered at axon hillock • point of decision • integration • Threshold potential • Depolarization; • approximately 10 mV • EPSPs  AP ~

  5. +40 0 -60 -70 -80 Time Em

  6. +40 C & E gradients drive Na+ into cell Depolarization Na+ influx 0 Em -60 -70 -80 Time

  7. + - Na+ K+

  8. + - Na+ K+

  9. +40 Repolarization K+ efflux 0 Em -60 -70 -80 Time

  10. + - Na+ K+

  11. + - Na+ K+

  12. After- hyperpolarization +40 0 Em -60 -70 -80 Time

  13. Refractory Period • After AP • time-out • prohibits or resists AP • absolute & relative ~

  14. Refractory Period • Absolute refractory period • Na+ channels deactivate • will not trigger AP • must reset • one-way transmission of signal • Ball & Chain Model ~

  15. Na+ channel deactivation

  16. Na+ channel deactivation

  17. Refractory Period • Relative refractory period • during after-hyperpolarization • requires greater depolarization to reach threshold ~

  18. Frequency Code • Intensity of stimulus • frequency of APs • Pattern • Type of stimulus • Brain area that receives signal • Visual, auditory, pain, etc. • Doctrine of Specific Nerve Energies ~

  19. 1. 2. 3. FREQUENCY CODE Weak stimulus Moderate stimulus Strong stimulus

  20. Saltatory Conduction • Myelinated neurons • oligodendrocytes & Schwann cells • Long distances transmission • APs relatively slow, regenerates • EPSPs - fast, decremental • Saltatory: combines both types of current • speed without loss of signal ~

  21. Saltatory Conduction • Nodes of Ranvier • action potentials • no myelin • Myelinated portions • passive current • decremental but triggers AP at next node ~

  22. Saltatory Conduction Nodes of Ranvier

  23. Graded Summation longer duration 10-100 msec chemical-gated passive spread instantaneous decremental All-or-none short 1-2 msec voltage-gated propagated slow nondecremental PSPs vs APs

More Related