Resting Membrane & Action Potentials Flashcards
What is excitability
Allows cells to establish a means of communication to their own interior or other cells
Define RMP
Starting point for a cell to be potentially excited
What is the extracellular and intra cellular concentration and mv for K and Na
Na 145 (out) 12 (In) 67(mv)
K 4.5 (out) 155 (In) -95 (mv)
What channels most affect RMP
K leak channels
RMP is primarily due to the permeability of plasma membrane to what
K
Is the membrane permeable to Na?
Not so much
Role of ATPase in cell membrane potentials
Move 3 Na outside and 2 K inside cell
Does not contribute much to RMP
RMP of cardiac/skeletal muscle
-80 to -90 mv
RMP of smooth muscle
-60 mv
RMP of Neurons
-60 to -70 mv
Difference in diffusion and electrostatic forces
Diffusion is movement of chemicals down their gradients
Electrostatic is movement of charges to their opposite charges
RMP and K leak channels cause a build up of charges where
+ extracellular
- intracellular
Ach binds to what in muscle NMJ
Nicotinic Ach receptors
How to calc. Electrochemical forces
Diffusion + electrical
What is the equilibrium potential of Na alone
+66 mv
What is the equilibrium potential of K alone
-91 mv
What is the Nernst Equation
E(ion) = (61.5)/Z log(xout/xin)
Z = charge of ion (+/-)
Xout = concentration of ion outside cell
Xin - concentration of ion inside cell
How to calculate driving force
(RMP) - (Eion)
What is driving force
How likely it is for an ion to move in or out of a cell
What does a + DF mean
Efflux of ion
What does a (-) DF mean
Influx of ion
What is inside, outside and E for Cl
Out = 116 In = 4.2 E = -89
K leak channels contribute what E to RMP
-91 mv
Na diffusion contributes what E to RMP
+5
