Membrane Physiology: Resting and Reversal Potentials

Question 1

What can disrupt the resting membrane potential of a cell?

Answer 1

A change in ion concentrations either inside or outside of a cell

Question 2

The larger the membrane potential the larger…?

Answer 2

The ability to do work

Question 3

What is used to do work in cells?

Answer 3

Difference in ion concentrations

Question 4

What determines the movement of ions?

Answer 4

The sum of differences in the electrical and chemical (concentration) gradient

Question 5

What is meant that RMP is in equilibrium?

Answer 5

The net influx is equal to efflux of ions

Question 6

Which ion has the greatest affect on the membrane potential?

Answer 6

The most permeable one

Question 7

Is K+ concentration or chemical gradient stronger?

Answer 7

Concentration gradient

Question 8

What is the relative concentration difference of Na+ inside and outside of the cell?

Answer 8

x10 more outside the cell

Question 9

What is the relative concentration difference of K+ inside and outside of the cell?

Answer 9

x40 more inside the cell

Question 10

What is the relative concentration difference of Ca2+ inside and outside of the cell?

Answer 10

x25k more outside the cell

Question 11

What is the relative concentration difference of Cl- inside and outside of the cell?

Answer 11

x30 more outside the cell

Question 12

What does the magnitude of the electrical force depend on?

Answer 12

The membrane potential

Question 13

What does the direction of the electrical force depend on?

Answer 13

Ion charge

Question 14

What is the net force?

Answer 14

Sum of chemical + Electrical gradient

Question 15

How does each ion attempt to change the membrane potential?

Answer 15

Each ion tries to move the membrane potential towards its equilibrium potential

Question 16

Why is the equilibrium potential also called the reversal potential?

Answer 16

Because the typical concentration gradient is reversed

Question 17

What is Cl- Erev?

Answer 17

-90 mV

Question 18

What is Na+ Erev?

Answer 18

+65 mV

Question 19

What is Ca2+ Erev?

Answer 19

+130 mV

Question 20

What is K+ Erev?

Answer 20

-95 mV

Question 21

What three terms are synonymous?

Answer 21

Nernst Potential, Reversal Potential, Equilibrium Potential

Question 22

What is an equilibrium potential?

Answer 22

The membrane potential at which the force of the concentration gradient = electrical gradient

Question 23

What is the Nernst equation?

Answer 23

Ex= (60mV/z) log ({X}o/{X}i)

Question 24

What does z stand for in the Nernst equation?

Answer 24

Valence number of electrons including the charge

Question 25

What value does a number less than one carry on the log scale?

Answer 25

A negative

Question 26

What is the net driving force?

Answer 26

Membrane potential-Erev | Current MP-Reversal Potential

Question 27

What is a local potential?

Answer 27

A depolarization of the membrane by an influx of Na+ at a specific point on the membrane only

Question 28

What is another name for a local potential?

Answer 28

Graded response

Question 29

What happens if another Na+ opens next to the initial channel?

Answer 29

It will have an additive affect causing the membrane to become more depolarized

Question 30

What happens to the Na+ that has entered the membrane?

Answer 30

It diffuses throughout the inside of the dendrite getting less concentrated as it moves

Question 31

What happens to a local response?

Answer 31

It degrades over space and time

Question 32

What is another term for local potential?

Answer 32

Synaptic potential

Question 33

Where do local potentials mostly occur?

Answer 33

In dendrites and somata of neurons

Question 34

What happens when a sufficient number of depolarizing synaptic potentials occur?

Answer 34

The axon initial segment will become depolarized

Question 35

What is a significant depolarization?

Answer 35

A depolarization of about 10 mV

Question 36

What is an action potential?

Answer 36

A propagated potential that travels along the axon of a neuron

Question 37

What are the properties of Na+ channels?

Answer 37

Open quickly to a small depolarization

Question 38

What are the properties of K+ channels?

Answer 38

Open slowly to a large membrane depolarization; involved with action potential termination

Question 39

What is the refractory period?

Answer 39

The time period in which Na+ channels are inactivated by the inactivation gate to ensure unidirectional propagation of the AP

Question 40

What is the absolute refractory period?

Answer 40

When the Na+ gates are inactivated and absolutely no AP can occur

Question 41

What is the relative refractory period?

Answer 41

Another AP can be produced only if the stimulus is large enough (while the K+ channels are still closing)

Question 42

What is peripheral neuropathy?

Answer 42

Loss of peripheral myelin which slows conductance