W4 Flashcards
Receptor potential
changes from resting -60mv to -53mv when nerve ending is activated.
Synaptic potential
resting potential in innervated cell changes from -70 to -65 when innervated by one synapse.
Action potential
The impulse that travels down the axon. resting at -60, spiking at +40
What triggers and action potential
Stimulation above the threshold of -50mv
What causes the resting potential at equilibrium?
When the balance between the electrical force and the chemical force has been met.
What is the voltage of resting potential when Kcl is at a concentrations difference of 1:10 at room temperature?
58 mV
What is the nernst equation
It calculates the electrochemical equalibrium or “umkehrpotential” E(x) = RT/zF In cX1/cX2
(E(x)= 58/z log cXout/cXin
R= Gaskonstante - stays the same
T = absolute temperature - stays the same
F = faradaian number - stays the same
z= charge (Ladung) (changes for different molecules) K+ Cl- or Ca2+
cX = concentration of substance X
What is the equalibrium for cK 140 inside, 5 outside
E(K) = 58/1 log 5/140 = -84mv
what is the electrochemical equalibrium at cNa 10 inside, 150 outside.
E(Na) = 58/1 log 150/10 = +68mv
Why is the giant quid axon so big?
It’s axons are not myelinated, so have relied on size to increase speed. It is 800 µm whereas the mammalian is 2µm
What are the concentrations of K+, Na+, Cl- and Ca2+ in intra and extracellular conditions?
K+ is more concentrated inside the cell
All others are more concentrated outside the cell.
RT/F at room temperature an in people.
room temperature = 58
in people = 61
The concentration of which molecule decides the resting potential of the cell.
Concentration of K+ inside the cell.
What is the Goldmann equation?
This calculates the resting potential of the cell.
Is the resting potential dependent on extracellular Na+ concentration?
only very slightly.
