How Nerves Work 2 Flashcards
Why do neurons exist?
To send electrical signals.
What are the 3 types of electrical potentials and give their description?
Action - transmit signals over long distances
Graded - decide when action potentials should be fired
Resting Membrane Potential - helps cell be ready to respond
What is the resting membrane potential of a cell?
-70mV (negative relative to the rest of the cell)
Describe the sodium/potassium pump.
It spreads across the cell membrane and uses ATP to transfer sodium out of the cell and potassium in.
Describe leaky potassium ion channels.
They allow potassium out of the cell down the concentration gradient.
What happens as the cell becomes more negative due to leaky potassium ion channels?
The cell draws potassium ions back in which is called the electrical gradient.
What is Nernst’s rule?
The equilibrium potential is the membrane potential at which the electrical gradient is exactly equal and opposite to the concentration gradient.
What is the equation for Nernst’s rule?
E = RT log10 [ion]o
zF [ion]i
What do R, T, z and F stand for in the Nernst’s rule equation?
R = gas constant T = absolute temperature (K) z = valence of the ion F = faraday constant
What does a higher potassium concentration outside of the cell mean for the concentration gradient?
It means the concentration gradient will be smaller which will cause the cell to depolarise.
Why can too much potassium kill you?
The heart doesn’t have a blood barrier to protect it from the change in the resting membrane potential.
What are the ion concentrations inside of the cell for potassium, sodium and chlorine?
140
15
10
What are the ion concentrations outside of the cell for potassium, sodium and chlorine?
5
150
110
What is Goldman’s Equation?
Vm = RT log10 Pk [K+]o + PNa [Na+]o + PCl [Cl-]o
F Pk [K+]i + PNa [Na+]i + PCl [Cl-]i
