Electrophysiology II: The Basis of Bioelectricity Flashcards
What are the differences between ion pumps and channels?
Pumps require ATP and active transport to maintain ion flow but channels cause the change in membrane potential, which is driven by the stored energy in the electrochemical gradients generated by the pumps
What role do pumps have on neuronal signalling?
No role, they are not directly involved in neuronal signalling, they just maintain the [X] over a long time
What is the relationship between the Na+ pump and action potential?
No relationship, you need the pump to establish conditions of AP but doesn’t cause AP or restore membrane potential
What is charge in terms of the cell?
Q, the ions
What is current in terms of the cell?
I, the movement of charge
What is voltage in terms of the cell?
V, the separation of charge (Vm)
What is resistance in terms of the cell?
R, the ion channels
What is capacitance in terms of the cell?
C, the lipid bilayer
What is the principle of electroneutrality?
If you have a solution of charged ions (e.g -ve), then you must have the same amount of oppositely charged ions too (+ve)
What is the voltage across the membrane due to?
Due to small separation of charge, not the change in [X] across a membrane
What is the equilibrium potential?
The voltage
What can be used to determine the equilibrium potential?
Nernst Equation
What is net flow like at equilibrium?
At equilibrium, inward and outward flow are equal. If driving force due to concentration is inward, driving force due to voltage must be outward
What happens if Vm is different to Eion?
There is a net difference in the electrochemical driving force
What is the electrochemical driving force?
- A potential that drives ion flow across the membrane, where potential is voltage and ion flow is current
- It is the difference between Vm and Eion, the greater the difference, the greater the driving force
