petra
Uploaded by
23 SLIDES
398 VUES
230LIKES

Understanding Action Potentials: Mechanisms, Characteristics, and Implications

DESCRIPTION

This lesson delves into the fundamental principles of action potentials, a crucial aspect of neural communication. It discusses large membrane potential changes facilitated by electrically gated channels, highlighting key features such as depolarization, repolarization, and the refractory period. The process includes sodium influx and potassium efflux, integrating concepts like frequency coding to signal stimulus intensity. Additionally, the lesson covers saltatory conduction in myelinated neurons, detailing how action potentials propagate efficiently along axons at the nodes of Ranvier.

1 / 23

Télécharger la présentation

Understanding Action Potentials: Mechanisms, Characteristics, and Implications

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 11

  2. Action Potentials • Large and rapid change in membrane potential • electrically-gated channels • EPSPs • threshold potential • Occurs in axon • triggered at axon hillock ~

  3. axon hillock

  4. AP Characteristics • Voltage-gated channels • All or none • Slow • Non-decremental • Self Propagated • regenerated ~

  5. +40 0 -55 -65 -75 Time Vm

  6. +40 0 -55 -65 -75 Time Vm

  7. +40 0 -55 -65 -75 Time Vm

  8. +40 0 -55 -65 75 Time Vm

  9. +40 C & E gradients drive Na+ into cell Depolarization Na+ influx 0 Vm -55 -65 -75 Time

  10. +40 = 105 mV Amplitude Depolarization Na+ influx 0 - 65 mV to +40 mV Vm -55 -65 -75 Time

  11. +40 Repolarization K+ efflux 0 Vm -55 -65 -75 Time

  12. After- hyperpolarization +40 0 Vm -55 -65 -75 Time

  13. Refractory Period • after AP • won’t fire again • relative & absolute • Relative • during after hyperpolarization • requires greater depolarization ~

  14. +40 0 Time Relative Refractory Period Vm -55 -65 -75

  15. Absolute refractory period • Na+ channels deactivate • will not trigger AP • must reset • Ball & Chain Model ~

  16. Na+ channel deactivation

  17. Na+ channel deactivation

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

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

  20. Saltatory Conduction • Myelinated neurons • oligodendroglia & Schwann cells • Transmit long distances • 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 • Myelinated • like electricity through wire • decremental but triggers AP at next node • Safety factor - trigger AP across 5 nodes • .2 - 2 mm apart • larger neurons  farther apart ~

  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