Chapter 3: The Neuronal Membrane at Rest

Question 1

the difference in electrical charge across the membrane in the resting neuron

Answer 1

resting membrane potential

Question 2

a brief reversal of the resting membrane potential

Answer 2

action potential

Question 3

3 main players in making membrane potential

Answer 3

1. cytosol and extracellular fluid
2. membrane
3. transmembrane proteins

Question 4

key ingredient in ICF and ECF

Answer 4

water

Question 5

key feature of water

Answer 5

polar solvent

Question 6

cytosol and ECF are composed of water and ()

Answer 6

ions

Question 7

the interaction between charged ions and the polar water molecules results in () around the ions

Answer 7

spheres of hydration

Question 8

hydrophobic compounds don’t dissolve in water due to ()

Answer 8

even electrical charge

Question 9

proteins that help control resting and action potentials

Answer 9

transmembrane proteins

Question 10

bond between amino acid monomers in proteins

Answer 10

peptide bonds

Question 11

transmembrane proteins that have polar and nonpolar R groups; involved in ion selectivity and gating

Answer 11

channel proteins

Question 12

transmembrane proteins that use ATP to transport certain ions across the membrane; also involved in neuronal signalling by pumping out Na+ and Ca2+ ions

Answer 12

ion pumps

Question 13

a functioning nervous system required movement of (1) across (2)

Answer 13

1. ions
2. membrane

Question 14

occurs when dissolved ions passively distribute evenly

Answer 14

diffusion

Question 15

ions flow down concentration gradient when: (2)

Answer 15

1. channels are permeable to ions
2. concentration gradient exists across the membrane

Question 16

the force exerted on a charged particle; reflects the difference in charge between an anode and a cathode

Answer 16

electrical potential

Question 17

relative ability of an electrical change to migrate from one point to another

Answer 17

electrical conductance

Question 18

in order to drive ions across the membrane electrically: (2)

Answer 18

1. conductance - channels are permeable to ions
2. voltage - electrical potential difference across the membrane

Question 19

voltage across the neuronal membrane at any moment

Answer 19

membrane potential (Vm)

Question 20

resting membrane potential value is around ()

Answer 20

-65 mV (inside is more negative compared to outside)

Question 21

at this potential, there is no net movement of ions when separated by a phospholipid membrane

Answer 21

equilibrium potential

Question 22

when the diffusional and electrical forces are equal and opposite, K+ stops moving

Answer 22

K+ ionic equilibrium potential

Question 23

how much charge can be stored within the vicinity of the membrane

Answer 23

capacitance

Question 24

ionic driving force

Answer 24

Vm - Eion; Vm = membrane potential; Eion = ionic equilibrium potential

Question 25

due to both electric potential and concentration gradient, Na+ will want to go inside the cell; thus it is crucial to ()

Answer 25

keep pushing Na+ out of the cell to maintain the electrochemical gradient

Question 26

an ATPase that degrades ATP when Na+ is present; ensures large [K+] inside cell and large [Na+] outside cell

Answer 26

Na+ - K+ pump

Question 27

how easy it is fro an ion to pass through the membrane

Answer 27

membrane permeability of the ion

Question 28

selectivity of K+ channels comes from the (1) in the (2) of the channels

Answer 28

1. amino acid arrangement
2. pore regiond

Question 29

K+ channels have () subunits

Answer 29

4

Question 30

the () allows the K+ channels to be selectively permeable to K+ ions only

Answer 30

pore loop-selectivity filter

Question 31

explain how K+ channels prevent smaller Na+ ions to pass through

Answer 31

• carbonyl oxygen atoms lining the channel pore displace water molecule bound to K+, allowing K+ to pass through
• the water molecules bound to smaller Na+ ions cannot interact with the oxygens and thus are not diplaced

Question 32

the resting membrane potential is close to Ek (ionic equilibrium potential of K+) because ()

Answer 32

the membrane is mostly permeable to K+

Question 33

increased extracellular K+ (polarizes/depolarizes) membrane

Answer 33

depolarizes