Action Potentials

Question 1

Normal ionic concentrations:

Answer 1

Na and Cl outside high ~ 150
K outside low ~ 5

Question 2

Active transport: How many ions moves at Na-K ATPase

Answer 2

3 NA ions out
2 K ions in

Question 3

Neuron membranes use ___ to move ions

Answer 3

pumps, transporters and channels

Question 4

what is chemical gradient

Answer 4

different concentratoins of ions in and out of cell

Question 5

what is equilibrium potential

Answer 5

when electrical gradient balances the chemical gradient

Question 6

what equation is used for equilibrium potential

Answer 6

Nernst equation

Question 7

Nernst equation:

Answer 7

E = RT/zF ln Co/Ci

Question 8

resting membrane potential

Answer 8

Na permeability is low
K permeability is high

Question 9

which equation calculates resting potential

Answer 9

Goldman

Question 10

Resting potential ____ mV

Answer 10

-50 to -70

Question 11

Cell membrane is made more negative on the inside

Answer 11

hyperpolarization

Question 12

Cell membrane is made less negative (or more positive) on the inside

Answer 12

depolarization

Question 13

Total current through channels depends on

Answer 13

driving force (fast) on the ions

Question 14

Specialized membrane channel proteins
that pass ions at high rate when open

Answer 14

voltage-dependent channels

Question 15

how many subunits make a potassium voltage channel

Answer 15

4 a and b subunits make one channel

Question 16

Play an important role in development of resting potential (some are open at resting potential)

Answer 16

potassium K channels voltage-dep

Question 17

Important for repolarization after action potential , in hyperpolarization and in neuronal inhibition

Answer 17

potassium K channels voltage-dep

Question 18

K pottasium channels are blocked by

Answer 18

TEA- tetraethylammonium

Question 19

which region is the voltage sensor in Na voltage channels

Answer 19

S4 region

Question 20

how many alpha helices do Na channels have

Answer 20

S1-S6

Question 21

Important for rising phase of action potential

Answer 21

voltage Na channel

Question 22

what can causes inactivation (open channel blocked by inactivation particle)

Answer 22

Maintained depolarization of Na channels

Question 23

Recovery from Na inactivation requires

Answer 23

repolarization for a few ms

Question 24

Na channels are block by

Answer 24

local anesthetics (lidocaine, procaine) or animal toxins (tetrodotoxin)

Question 25

action potential graph

Answer 25

threshold - rising phase - overshoot (refractory period ) - falling phase (na inactivation, k opens) hyperpolarization (na close)

Question 26

terminates AP

Answer 26

depolarization

Question 27

when can second AP occur

Answer 27

during relative refractory period, NOT absolute

Question 28

AP propagates by local currents with which axons

Answer 28

unmyelinated axons

Question 29

AP propagates by saltatory conduction with which axons

Answer 29

Myelinated axons

Question 30

what is Prion disease?

Answer 30

causes misfolding in endogenous prion membrane proteins

resulting in amyloids

Question 31

what is Creutzfeldt-Jakob?

Answer 31

Subacute spongiform encephalopathy prion disease