Lecture 22- Frequency Coding and Generator Potentials Flashcards
What is the first step in propagating the action potential?
Voltage gated channels cluster at the site
What is the second step in propagating the action potential?
Voltage gated channels are evenly distributed along the conductive region (unmyelinated axons)
What is the third step in propagating the action potential?
Voltage gated channels cluster at the Nodes of Ravien
What is the fourth step in propagating the action potential?
Capacitance slows down propagation
What is the fifth step in propagating the action potential?
Myelination reduced capacitance and increases velocity of propagation
What is the role of capacitance in a neuron?
Determines how quickly the neuron’s membrane potential responds to inputs
How does capacitance affect propagation?
Slows propagation
Must be discharged by ions coming in before next channel opens
What is the amplitude of voltage response proportional to?
The number of channels opened
What is the “Trigger Zone”?
Site where voltage gated K+ and Na+ channels cluster
What are the simple four action potential steps?
- Membrane is at rest (more “+” outside and more “-“ inside)
- Na+ channels open and depolarize
- Na+ channels close
- K+ channels open and repolarize
What is the role of myelination?
Myelination increases action potentials and speed by reducing capacitance
What happens during the refractory period?
Na+ channels close and K+ channels open…. which means there isn’t enough charge to reopen the previous Na+ channels
True or false: capacitance is extremely high between nodes (inter-nodal regions)
FALSE
Capacitance would be low because the membrane is discharges at the next node/opens v-gated channels without being troubled by the “-“ charge in-between=faster velocity
What does a low capacitance mean for velocity?
Faster velocity
What is the typical action potential duration?
In a typical nerve, the action potential duration is about 1 ms
