Lecture 10 - Membrane Potentials - Graded Potentials and Action Potentials Flashcards
Vm signals
Described in terms of changes from the resting membrane potential RMP
Leak channels
RMP is created by leak channels which are always open
Gated channels
Open and close depending on gating factors
Ligand gating
Voltage gating
Mechanical gating
What are 2 ways to categorize ion channels?
Gating and ion selectivity
Equilibrium potential
The inward and outward movements of that ion are equal and there is no net force on that ion
Relationship between permeability and Vm
Ions contribution to Vm is directly proportional to its permeability
Each permeable ion moves the membrane toward its own Eion
Which transport system is responsible for the ion concentration differences of the membrane potentials?
Na+ and K+ maintained by primary active transport
Cl- maintained by secondary active transport
What affects the size of a graded potential?
The number of ion channels open
-> Vm is determined by permeability!
Action potentials
Specialized membrane potential signals that can be rapidly transmitted long distances through an axon membrane
Which 2 types of voltage gated ion channels generate action potentials?
VGNC and VGKC
Describe the activation and inactivation gate of the Voltage gated sodium channel (VGNC)
Activation gate: opens rapidly in response to the depolarization
Inactivation gate: starts to open, then close
Describe the activation gate of the voltage gated potassium channels.
The gate responds to Vm crossing threshold but only after a delay.
Absolute refractory period
Second AP CANNOT be triggered no matter how strong the stimulus
Relative refractory period
A larger than normal stimulus can trigger a second AP
