Lec 3

Question 1

What are positively charged ions called?

Answer 1

Cations

Question 2

What is “the potential to do work (moving a charge from one place to another)” ?

Answer 2

potential difference (E)

Question 3

What is a negatively charged ion?

Answer 3

Anion

Question 4

What is “the net flow of charge from one point to another” ?

Answer 4

Current (I)

Question 5

What is “the resistance to movement of current” ?

Answer 5

Resistance (R)

Question 6

Potential difference (E) is measured in what unit of measurement?

Answer 6

Volts (V)

Question 7

Current (I) is measured in what unit of measurement?

Answer 7

Amperes (A)

Question 8

Resistance (R) is measured in what unit of measurement?

Answer 8

Ohms (Π)

Question 9

V = IR or E = IR

What do these equations represent?

Answer 9

Ohm’s Law

Question 10

If you were to increase the resistance what would happen to the voltage?

Are they proportionate?

Answer 10

increase

Yes they are proportionate

Question 11

If you were to decrease the potential difference or voltage, what would happen to your current?

Are they proportionate?

Answer 11

decrease in current

yes they are proportionate

Question 12

If you decrease your current, what will happen to your resistance?

Are they proportionate?

Answer 12

increase your resistance

they are inversely proportionate

Question 13

What is represented by the symbol (G) and is inversly proportionate ot resistance?

Answer 13

Conductance (G)

Question 14

What unit of measurement is used to measure Conductance (G) ?

Answer 14

Siemens (s)

Question 15

The generating a membrane potential requres what two things?

Answer 15

1. Ionic gradient - diffusion of ions toward lower []
2. ions flow to compartment that has opposite charge

I.E. electrical and chemical gradients.

Question 16

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?

Answer 16

False - don’t worry about the exact number of ions

Question 17

What equation can be sued to find the E_x that is necessary to balance an ionic concentration?

Answer 17

Nernst Equation

Ex = 58mV/z * log10 ([X]out / [X]in )

Question 18

The Nernst Potention for each common ion is?

Na+ = __

K+ = __

Ca²⁺ = __

Answer 18

Na+ = +65 mV

K+ = -90 mV

Ca²⁺ = +123 mV

Question 19

What equation is used to find the membrane potential, that includes multiple ions/channels?

Answer 19

Goldman Equation

Vm = 58log10 = Px[X]out …/ Px[X]in

Question 20

General permeabilities to each ion are:

PK = __

PNa = __

PCl = __

Answer 20

PK = 1

PNa = 0.035

PCl = 0.001

Question 21

Vm is generally around -64 mV. This can be changed by what 2 factors?

Answer 21

changing the gradient (Nernst potential)

or

changing relative permiability (in goldman)

Question 22

The Nernst potential is also called the “reversal potential.” What is this?

Answer 22

Because if the current reaches this potential, it reverses in the opposite flow.

Question 23

I = GE or I= V/R

What does this formula represent?

Answer 23

Ohm’s law

(with conductance)