Resting Membrane Potential

Question 1

What is the electrochemical gradient?

Answer 1

Differences in both electrical potential and chemical concentrations across a membrane

Question 2

What is excitability?

Answer 2

He ability of a cell to generate an electrical signal

Question 3

What cells generate electrical signals?

Answer 3

Brain, muscles, and the heart

Question 4

What is electronegativity?

Answer 4

The ability to greatly attract electrons in covalent bonds

Question 5

What is ionization (dissociation)?

Answer 5

Process of breaking ionic bonds as ions interact with water molecule

Question 6

What are ions?

Answer 6

Polar molecules. Where one side is “partially positive” (losing a large fraction of electron), where one side is “partially negative” (gaining a large fraction of electron)

Question 7

What is diffusion?

Answer 7

Ions/molecules move down their concentration gradient from high to low

Question 8

What is an electrical gradient?

Answer 8

Area where the overall charge of one location is higher than another

Question 9

What is an electrical current?

Answer 9

The movement of ions (diffusion of ions caused by electrical and chemical gradients)

Question 10

What is an electrical potential?

Answer 10

Refers to the difference in charge between two points

Question 11

What are plasma membranes?

Answer 11

Selectively permeable barrier separating inside of cell from extra cellular fluid

Question 12

What is the fluid mosaic model of a plasma membrane?

Answer 12

Multiple diverse and mobile components make up the cell membrane

Question 13

What does it mean if a plasma membrane is selective permeable?

Answer 13

Only certain molecules or ions can pass through it

Question 14

What is a phospholipid bilayer?

Answer 14

Two layers of phospholipids, hydrophilic heads at surface and hydrophobic tails on inside

Question 15

What are ion channels?

Answer 15

Specialized proteins in our cell membranes that allow ions to diffuse down concentration gradient. They are selectively permeable to certain ions

Question 16

What do transmembrane proteins allow for?

Answer 16

The passage of ions across the membrane

Question 17

Where can proteins exist?

Answer 17

In closed, open or inactive days states

Question 18

What are closed proteins?

Answer 18

Refers to proteins that havent been stimulated

Question 19

what are open proteins?

Answer 19

Refers to proteins that have been stimulated and are passing ions

Question 20

What are inactivated proteins?

Answer 20

Proteins that are being stimulated but have become “desensitized” to the stimulus and are no longer passing ions

Question 21

What do ion channels do?

Answer 21

Act as “gates” in an otherwise impermeable membrane “fence”

Question 22

What are some types of ion channels?

Answer 22

Ligand gated- neurotransmitters open
Voltage gated- activated by voltage change
Stretch and heat gated- hot/cold

Question 23

T/F ion channels do not indiscriminately pass all ions down their concentration gradient

Answer 23

True: ion channels either exclusively pass anions or cations. Some ion channels are selective and can only pass one type of ion

Question 24

what are ion pumps?

Answer 24

Transporters that use energy

Question 25

Which pump changes the resting membrane potential?

Answer 25

Sodium potassium pump

Question 26

What occurs in the sodium potassium pump?

Answer 26

3 sodium ions are moved out against their concentration gradient while 2 potassium ions are moved in against their concentration gradient (requires hydrolysis of ATP)

Question 27

What do the unequal exchange of charges in the sodium potassium pump help to do what?

Answer 27

Maintain the negative resting potential

Question 28

What are active transporters?

Answer 28

Actively move selected ions against concentration gradient, create ion concentration gradients

Question 29

What is excitability?

Answer 29

The ability of a membrane to conduct electrical charges in order thus creating the membrane potential (relies on the presence and ability to activate ion channels in the membrane)

Question 30

What is the resting membrane potential?

Answer 30

The difference in electrical charges across the membrane when there is no electrical current

Question 31

What determines the sign on the inside of the celll?

Answer 31

The direction of the charge If more positive on the inside the sign is + If more positive on the outside the sign is -

Question 32

What is electrophysiology?

Answer 32

The ability for electrical current to generate a physiological output

Question 33

What is Ohm’s law?

Answer 33

V=IR V= voltage I= current R= resistance

Question 34

How can we alter the electrical current?

Answer 34

Change voltage- role of iconic concentrations Change conductance- role of # of channels, role of channel properties

Question 35

How do we measure the electrical potential?

Answer 35

Use a voltmeter

Question 36

How does a voltmeter measure the membrane potential?

Answer 36

Microelectrode is placed inside the cell and the potential difference is determined by comparing to a ground placed in the bathing solution outside the cell

Question 37

What is the normal resting membrane potential?

Answer 37

-70 mV

Question 38

How can we change the resting membrane potential?

Answer 38

A change in the concentration of iconic species on either side of the membrane, the membrane potential will change

Question 39

T/F only small ionic fluxes lead to large and local changes in membrane potential

Answer 39

True a shift of 80 mV can be caused by a concentration change of only 0.000001 mM

Question 40

How do we determine the equilibrium potential for a particular ion?

Answer 40

Nernst equation

Question 41

What is the nearest equation?

Answer 41

Eion=61.54 log (ion out/ion in)

Question 42

What is the GHK equation used for?

Answer 42

Determining the overall resting membrane potential

Question 43

What is the GHK equation?

Answer 43

MV= 61.54 log (((Pk * K out) + (PNa * Na out) + (PCl * Cl in))/((Pk *K in) + (PNa * Na in) + ( PCl * Cl out)))