Electrochemical Equilibria Flashcards
What is an electrode?
Metal/glass extruded to a fine point filled with fluid, and a wire
When you measure intracellular electrical activity where is the electrode?
Inside the cell
When you measure extracellular electrical activity where is the electrode?
Outside the cell
What is patch clamping?
Electrodes sealed to cell surface
What is the structure of the apparatus used to measure electrical activity?
Electrodes fixed onto holders which are mounted onto micromanipulators
How do you observe cells when measuring electrical activity?
Phase-contrast microscopy
Cells only Petri dish
What is the intracellular range of potential?
100mV
What is the extracellular range of potential?
0.1mV
What allows electrochemical gradients to be established? (3)
Pumps move ions against their concentration gradient
Ion movement via channels is restricted/very slow
Membrane stores ionic charges on its inner and outer surfaces
What is capacitance?
The amount of electrical charge a cell can store on its inner and outer surface
Why can cells store ionic charges on its inner and outer membrane?
Ions have hydration shells
Interact with hydrophilic/polar phospholipid heads
What is electrical work done?
Energy required to separate oppositely charged ions across a membrane
What is voltage?
A measure of work done in separating charges across a membrane
What is the equilibrium potential?
When there is no net movement of ions
OR
When the electrical force/work done exactly balances the osmotic force/work done
How do you calculate the concentration gradient for a positive ion?
Concentration of ion outside divided by concentration of ion inside
