#10

Question 1

Effects of Doubling [K+]

Answer 1

More NEGATIVE because diffusion is increased

Question 2

Capacitance of Membrane

Answer 2

Determines how many charges is needed to change the voltage difference across the membrane
To change Vm from -60 to +40
Q = C * V

Question 3

Goldman-Hodgkin-Katz (GHK) Theory

Answer 3

Calculates membrane potential when the membrane is permeable to more than one ion
Constant Field Equation

Question 4

GHK z Term

Answer 4

Unused because more than one ion

Question 5

Pk is 20x more than Pna

Answer 5

PNa / PK = 1 / 20 = 0.05

Question 6

Driving Force Theory

Answer 6

Compares Diffusion v Voltage strength

Determines which direction ion is moving and with what magnitude

Question 7

How do we compare a diffusional force and a voltage force? (Different units)

Answer 7

Nernst converts strength of diffusional to voltage!

“Given a concentration difference across membrane, what voltage difference is required to balance it?”

Question 8

Drive Force (DF) Equation

Answer 8

DF = Voltage Force (Vm) - Concentration Force (Eion)

Question 9

Driving Force +

Answer 9

= Outward current of positively charges ions

Question 10

Driving Force -

Answer 10

= Inward current of positively charged ions

Question 11

K+ Permeability

Answer 11

20x that of Na+ = large flow (even though DF is outward and weak)

Question 12

Na+ Permeability

Answer 12

Small (even though DF is inward and strong)

Question 13

Cl- Permeability

Answer 13

Cell has no permeability to Cl-

Question 14

Conductance

Answer 14

Depends on the concentration of an ion.
Describes how easily an ion can pass
Need something to carry current or g = 0