Resting Membrane Potential

Question 1

Na concentration in ECF vs ICF

Answer 1

ECF: 135-147
ICF: 10-15

Question 2

K concentration in ECF vs ICF

Answer 2

ECF: 3.5-5
ICF: 120-150

Question 3

Cl concentration in ECF vs ICF

Answer 3

ECF: 95-105
ICF: 20-30

Question 4

HCO3 concentration in ECF vs ICF

Answer 4

ECF 22-28

ICF 12-16

Question 5

Ca concentration in ECF vs ICF

Answer 5

ECF: 2.1-2.8 (1.1-1.4 ionized)
ICF: 10^-7

Question 6

Pi concentration in ECF vs ICF

Answer 6

ECF: 1-1.4 (0.5-0.7 ionized)
ICF: 0.5-0.7 ionized

Question 7

T/F Ca and Pi can be bound to proteins and other organic molecules

Answer 7

T

Question 8

Large amounts of what ion can be sequestered w/in cells?

Answer 8

Ca

Question 9

Diffusion

Answer 9

Movement of molecules from 1 location to another solely as result of random thermal motion

Question 10

Concentration gradient

Answer 10

. Difference in concentration of molecules btw 2 locations

Question 11

If molecules are uncharged and movement is unrestricted, the concentrations will _____

Answer 11

Equalize due to simple diffusion

Question 12

Ion channels

Answer 12

. Proteins in membrane that form water-filled pores
. Conduct ions when open, don’t when closed
. Only certain ions pass through particular type of channel

Question 13

Characteristics of ion channels

Answer 13

. Selective
. Different configurations
. Many different channel types exist

Question 14

Ions diffuse through open channels due to what driving forces?

Answer 14

. Chemical driving force: concentration gradient across membrane
. Electrical driving force: separation of charges causes electrical gradient across membrane

Question 15

Electrochemical gradient

Answer 15

. Driving force for ions normally combo of both electrical and chemical driving forces
. Forces could be acting in same or opposite directions

Question 16

Membrane potential definition

Answer 16

. Potential (voltage) difference across cell membrane

. Caused by separation of charge across membrane

Question 17

How to measure membrane potential

Answer 17

.electrodes

. Units mV

Question 18

Resting membrane potential

Answer 18

. Membrane potential when cell is at rest (not firing action potentials)
. Inside is negative at -70mV

Question 19

Equilibrium potential

Answer 19

. Voltage when flux of particular ion due to the concentration gradient for the ion balances opposing flex due to electrical gradient for that ion

Question 20

Electrochemical equilibrium

Answer 20

. Potential difference (electrical gradient) is generated as ion moves
. Flux due to electrical gradient set up (opposes further movement of ion) becomes equal in magnitude to flux from chemical gradient
. Inward flux and outward flux are equal

Question 21

Electrical properties of neuron determined almost entirely by ____

Answer 21

Na and K channels

Question 22

Primary determinants of resting membrane potential

Answer 22

. Differences in concentrations of ions across the cell

. Difference in membrane permeability to ions (conductance)

Question 23

Driving force created by _____

Answer 23

Concentration differences determined by difference between equilibrium potential and membrane potential at that time

Question 24

Net flux of ion determined by ____

Answer 24

Flux =(driving force)(permeability)

Question 25

At any stable membrane potential, the net flux of Na and net flux of K _____

Answer 25

Are equal and opposite each other

Question 26

Na-K-ATPase

Answer 26

. Transporter in cell membrane
. 3 Na out per 2 K in
. Pump is electrogenic but only small amount

Question 27

T/F Na-K-ATPase contributes largely to resting membrane potential

Answer 27

F, it only contributes a small amount

Question 28

How does membrane permeability change of an ion?

Answer 28

. Opening or closing channels that conduct that ion