Lec 3 Flashcards
What are positively charged ions called?
Cations
What is “the potential to do work (moving a charge from one place to another)” ?
potential difference (E)
What is a negatively charged ion?
Anion
What is “the net flow of charge from one point to another” ?
Current (I)
What is “the resistance to movement of current” ?
Resistance (R)
Potential difference (E) is measured in what unit of measurement?
Volts (V)
Current (I) is measured in what unit of measurement?
Amperes (A)
Resistance (R) is measured in what unit of measurement?
Ohms (Π)
V = IR or E = IR
What do these equations represent?
Ohm’s Law
If you were to increase the resistance what would happen to the voltage?
Are they proportionate?
increase
Yes they are proportionate
If you were to decrease the potential difference or voltage, what would happen to your current?
Are they proportionate?
decrease in current
yes they are proportionate
If you decrease your current, what will happen to your resistance?
Are they proportionate?
increase your resistance
they are inversely proportionate
What is represented by the symbol (G) and is inversly proportionate ot resistance?
Conductance (G)
What unit of measurement is used to measure Conductance (G) ?
Siemens (s)
The generating a membrane potential requres what two things?
- Ionic gradient - diffusion of ions toward lower []
- ions flow to compartment that has opposite charge
I.E. electrical and chemical gradients.
The number of ions that flow in and out oof a cell to make a membrane potential is tiny and the exact concentration is important.
T or F?
False - don’t worry about the exact number of ions
What equation can be sued to find the Ex that is necessary to balance an ionic concentration?
Nernst Equation
Ex = 58mV/z * log10 ([X]out / [X]in )
The Nernst Potention for each common ion is?
Na+ = __
K+ = __
Ca2+ = __
Na+ = +65 mV
K+ = -90 mV
Ca2+ = +123 mV
What equation is used to find the membrane potential, that includes multiple ions/channels?
Goldman Equation
Vm = 58log10 = Px[X]out …/ Px[X]in
General permeabilities to each ion are:
PK = __
PNa = __
PCl = __
PK = 1
PNa = 0.035
PCl = 0.001
Vm is generally around -64 mV. This can be changed by what 2 factors?
changing the gradient (Nernst potential)
or
changing relative permiability (in goldman)
The Nernst potential is also called the “reversal potential.” What is this?
Because if the current reaches this potential, it reverses in the opposite flow.
I = GE or I= V/R
What does this formula represent?
Ohm’s law
(with conductance)
