10/12 Resting Membrane Potential - Rogers 2017 (Completed) Flashcards
What is the resting or starting state of excitatory cells? 3
Negative voltage on interior of the cell
What is the ratio of K+ and Na+ outside relative to inside? 5
K+ —> 1:30
Na+ —> 10:1
(Out:in)
(Extracellular:intracellular)
Why do potassium leak channels only function when the gradient inside and outside are somewhat the same? 6
Because Active transport NA+/K+***
What primarily establishes membrane potential? 7
The plasma membrane permeability to potassium ions
What are two main mechanisms by which potassium transverses the plasma membrane? 8
Na+/K+ pump - active
K+ leak channels - passive
What’s the exchange rate for potassium to sodium? Where are they going to? 9
3 Na+ —> going out side
2 K+ —> coming inside
What is the ratio of potassium leak channels to sodium leak channels? What does this mean? 10
100:1
This means K+ ism ore likely to leave the cell than Na+
What’s the resting membrane potential of muscle (cardiac/skeletal), SM, and neurons? 11
Cardiac/skeletal —> -80 - -90mv
Smooth muscle —> -60mv
Neurons —> -60 - -70mv
During the development of a membrane potential what are the forces acting on the ions? 12
Concentration gradients
Electrostatic forces (electrical gradients)
What are electrostatic forces (electrical gradients)? 13
The diffusion of Na+ and Cl- to their oppositely charged compartment
What factors produce an electrochemical force? 14
Diffusion force + Electrostatic force
What is the Equilibrium potential of sodium?
+66mv
What is the Equilibrium potential of potassium ions? 16
-91mv
What is the Nernst Equation? 17
Eion mv = 61.5 / z log [x] out / log [x] in
Z —> charge of the ion
What does a negative or positive result from the Nernst Equation indicate?
Negative —> there will be a net influx
Positive —> there will be a net efflux
