Membrane Potentials and Action Potentials Flashcards Preview

physiology (Woods) > Membrane Potentials and Action Potentials > Flashcards

Flashcards in Membrane Potentials and Action Potentials Deck (17):
1

what are the basic structures in a neuron

cell body
dendrites
axon

2

what does the cell body do

houses the nucleus and other typical cell organelles

3

what do dendrites do

they are cellular extensions of the neuron and characterized by the presence of ligand (neurotransmitter) gated ion channels. They also conduct local potentials

4

what is an axon

extension of the cell body and is typically opposite the side of the cell body where dendrites are located (covered by the plasma membrane).
* characterized by the presence of voltage-gated ion channels and the ability to conduct an action potential

5

define diffusion potential

caused by an ion concentration difference on either side of a membrane

6

define nernst potential

diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion through the membrane

7

define electrical dipole layer

dichotomous distribution of ions on either side of the membrane represents a voltage change

8

what assumptions are made when using the Nernst equation

*equation can only be used for one ion at a time
* membrane must be completely permeable to that ion
* ion must be at equilibrium

9

what are characteristics of action potential propagation

* it is all or none
* it is self-propagating: each region of depolarization serves to generate action potentials on either side
*it is non-decremental: it does not decrease in strength

10

what is the difference between ligand and voltage gated channels

ligand involves the attachment of a chemical messenger while voltage involves a change in the membrane potential

11

steps for action potential propagation

1. resting stage (-90mV)
2. Depolarization stage (membrane becomes permeable to Na+ and may overshoot large axons)
3. repolarization stage (Na+ channels close, K+ channels open more than normal)
4. Sodium and Potassium conductance

12

difference between orthodromic and antidromic direction

orthodromic direction is the direction normally taken while antidromic is the opposite directions

13

what is the principle lipid found in myelin sheaths

sphingomyelin

14

what does dendrites mean

branches

15

what is axolemma characterized by

it is a plasma membrane characterized by the presence of voltage-gated ion channels and the ability to conduct an action potential

16

what does the cell membrane function to maintain

separate intracellular and extracellular environments

17

what are ways to increase the propagation of an action potential?

increasing the diameter of the axon and increasing the membrane resistance of the axon