membrane potentials

Question 1

usual RMP (resting membrane potential)

Answer 1

-70 mV to -90 mV

Question 2

types of excitable cells that transduce and transmit the impulse/electric event down the cell membrane

Answer 2

muscle, heart, nerve

Question 3

what does RMP stand for

Answer 3

resting membrane potential inside the cell

Question 4

what are the most important ions involved in cell membrane potentials?

Answer 4

sodium, chloride, potassium

Question 5

what do you call an electrical potential across the cell where the electrical forces balance concentration forces?

Answer 5

nernst potential

Question 6

what 3 things determine the nernst potential for a specific ion

Answer 6

concentration gradient
electrical gradient (electrical charge of the ion)
the electrolyte permeability across cell

Question 7

the nernst potential for potassium is?

Answer 7

-94 mV

Question 8

the nernst potential for sodium is ?

Answer 8

+ 61 mV

Question 9

the nernst potential for calcium is?

Answer 9

+134

Question 10

which is 100 times more permeable to the membrane and contributes more to the RMP Na+ or K+

Answer 10

K+

Question 11

at rest, high ____ “leak” out of the cell

Answer 11

K+

Question 12

who created the nerve action potential

Answer 12

alan hodgkins and andrew huxley

Question 13

what initiates the opening of the Na+ channels?

Answer 13

strong stimulus

Question 14

if the stimulus is strong enough, what might occur?

Answer 14

threshold will be reached

Question 15

the threshold is reached and the voltage gated Na+ channels fly open (activation gate) in which stage?

Answer 15

depolarization
the membrane potential rises rapidly towards zero

Question 16

the action potential now rises beyond the zero level and the interior of the cell becomes positive

Answer 16

in the overshoot stage “action potential”

Question 17

which stage do the Na+ channels (inactivation gates) close and the voltage-gated K+ channels open?

Answer 17

repolarization
K+ rapidly diffuses out of the nerve cell and the interior of the cell becomes more negative

Question 18

Na+ channels “inactivation gates” will not reopen until they are “reset” to the original RMP level
-In a depolarized state, Na+ channels will not reopen and muscle membrane cannot conduct action potential
ex: when using succinylcholine, muscle relaxants

Question 19

in which stage does K+ move of out of the cell during the repolarization stage and passes the RMP moving toward the nernst potential?

Answer 19

hyperpolarization

Question 20

hyperpolarization contributes to which period?

Answer 20

refractory period

Question 21

what happens in the refractory period

Answer 21

the nerve/muscle is more difficult to stimulate because its hyperpolarized

Question 22

during the hyperpolarization/refractory period is the cell more negative or positive?

Answer 22

more negative because it’s trying to reach its nernest potential while K+ channels are open

Question 23

how much % of energy from brain fuels the Na+/K+ pump to carry out action potentials

Answer 23

70%

Question 24

w/ each action potential, ___ leaves cell and ____ enters

Answer 24

K+, Na+

Question 25

which stimuli invades the membrane and causes Na+ to diffuse inward through the nerve or muscle membrane and has the potential to set off an action potential?

Answer 25

mechanical disturbance, chemical effects, electrical stimulation

Question 26

threshold is all or none

Answer 26

it’s either reached or not reached

Question 27

what do you call it when the stimulus is not strong enough so an action potential is not generated?

Answer 27

local subthreshold potentials

Question 28

which refractory period can still generate an action potential if the stimulus is stronger than normal?

Answer 28

relative refractory period

Question 29

which refractory period cannot generate an action potential regardless of a strong stimulus

Answer 29

absolute refractory period

Question 30

in the relative refractory period the cell is more negative than it usually is

Question 31

local anesthetics- binds to and blocks the insides of Na+ channels making it difficult to open
low ECF K+ concentration- hyperpolarizes the membrane and RPM becomes more (-) = less excitability
High ECF Ca+ concentration

are all examples of what

Answer 31

membrane stabilizers