The Membrane Potential

Question 1

Know what a dendrite, axon, axon hillock, soma, and synaptic cleft are.

Answer 1

Do it.

Question 2

What is a coulomb a measure of?

Answer 2

Electrical charge (charge transported by 1 Amp for 1 sec)

Question 3

Coulombs of a proton?

Answer 3

1x10(-19) C

Question 4

What is Avagadro’s #?

Answer 4

Molecules in a substance

6.022 x 10(23)

Question 5

What is Faraday’s Constant?

Answer 5

Charge on a mole of any monovalent ion

Coulombs X Avagadro

Question 6

What is voltage a measure of?

Answer 6

Potential Difference (E)
Work required to move a unit of charge from one point to another

Question 7

What is current?

Answer 7

Current is the net flow of charge. It is measured in amperes (C/sec).

Question 8

What is resistance?

Answer 8

Measure of the ease with which a current flows
Measured in Ohms
E/I

Question 9

What is conductance? Measurement?

Answer 9

Reciprocal of Resistance (I/E)

Siemens

Question 10

Relative levels of Na, K, and Cl inside the cell (rather than outside the cell)

Answer 10

High K+ in cell

Low Na and Cl inside

Question 11

What do ions pass through in a cells?

Answer 11

ion specific channels

Question 12

What is the ionic equilibrium potential?

Answer 12

An electrical potential difference across the membrane caused by the selective permeability/ionic gradients of the cell membrane.

Question 13

The thin membrane facilitates what occurance when positive ions leave the cell.

Answer 13

Attraction of negative ions to the opposite side of the membrane.

Question 14

Is most of the cellular fluid chargeD?

Answer 14

No

Question 15

T or F. Equilibrium is established when there is no net ion movement across the cell membrane.

Answer 15

True

Question 16

What influences the rate of flow of an ion across a PM?

Answer 16

Concentration Gradient
Voltage Difference
Conductance of Ion Channels

Question 17

What is the Nernst equation used for?

Answer 17

Determines the equilibrium potential for a single ion

Question 18

What is the Nernst equation?

Answer 18

E = [(58mV)/z] x log [(outside ion conc)/(inside ion conc)]

Question 19

When would you use 61 instead of 58?

Answer 19

Body temp (instead of RT)

Question 20

What does the principle of electrical neutrality state?

Answer 20

Under biological conditions, the bulk concentrations of cations and anions in a compartment are equal.

Question 21

What is Donnan Equilibrium a study of?

Answer 21

It shows how the electrical potential across a membrane must balance the conc gradients or K and Cl.

Question 22

What is the Donnan Equilibrium equation?

Answer 22

[(Kout)(Clout)] = [(Kin)(Clin)]

Question 23

The Na/K+ pump burns up # ____, pumps out # _______ and takes in # ________.

Answer 23

1 ATP
3 Na
2 K

Question 24

What is the Goldman Equation?

Answer 24

The nernst equation, but for multiple ions at once.

Question 25

What does the Goldman equation take into account?

Answer 25

Concentration gradients of different ions and relative permeability of the membrane

Question 26

What is the Goldman equation?

Answer 26

See page 1-7 (pain to type in)

Question 27

Ratio of Pk:PCl:PNa

Answer 27

1: 0.45: 0.02

Question 28

Name three properties that are responsible for maintenance of the transmembrane potential

Answer 28

Transmembrane Resistance (Resting) Axial Resistance Membrane Capacitance

Question 29

What is input resistance? the equation?

Answer 29

relationship btw current injected and change in mem pot. | = (change in V) / I

Question 30

What determines input resistance?

Answer 30

of ion channels

Question 31

What is the specific membrane resistance?

Answer 31

The resistance of a unit area of membrane

Question 32

Input resistance formula using specific mem. resistance

Answer 32

=Rm/(4pir(2))

Question 33

The greater the area of a cell, the ____ its resistance.

Answer 33

Lower

Question 34

A neuron smaller neuron fires faster than a larger one because...

Answer 34

(With constant current) the small neuron's higher resistance will cause a higher E

Question 35

What is the relationship of membrane resistance and axial resistance to a subthreshold potential value moving down an axon

Answer 35

High Mem. Res = Father Distance Traveled | High Axial Res = Shorted Distance Traveled

Question 36

What is lambda?

Answer 36

The length constant, distance over which an electric potential decrements to 37% of peak value

Question 37

What is the equation of lambda?

Answer 37

= sq. rt (Rm/Ri)

Question 38

Larger Rm = ______ lambda

Answer 38

Larger

Question 39

Larger lambda increased likelihood of_______

Answer 39

summation

Question 40

What might the location of the synapse on a cell matter?

Answer 40

Different areas have diff #s of voltage dependent sodium channels

Question 41

Relationship between diameter and electronic speed?

Answer 41

Synaptic potential will e larger in a small dendritic process than a large one Larger dendrite will spread farther

Question 42

What is the membrane time constant?

Answer 42

Time necessary for the electrotonic potential to decree to 37% of its original peak.

Question 43

Equation for membrane time constant?

Answer 43

(Membrane Resistance) (Membrane Capacitance)

Question 44

A larger tau means what for summation?

Answer 44

Better chance