Electrophysiology of Neurons

Question 1

electrical potential is the difference in the

Answer 1

concentration of charged particles between one point and another

Question 2

electrical potential is a form of potential energy that can

Answer 2

produce a current

Question 3

does resting membrane potential have the same charge across the plasma membrane?

Answer 3

no it varies

Question 4

how much potential does resting membrane potential have?

Answer 4

much less than a flashlight battery

Question 5

an electrical current is a flow of

Answer 5

charged particles from one point to another

Question 6

sodium ions generate a current in the body from the

Answer 6

flow of ions with potassium through gated channels in the plasma

Question 7

gated membrane channels can be opened and closed by what?

Answer 7

various stimuli

Question 8

from the gated membrane channels being opened and closed this allows what?

Answer 8

cells to turn electrical currents on and off

Question 9

ligand-gated ion channels can open when what binds to the receptor?

Answer 9

the appropriate chemical (neurotransmitter)

Question 10

voltage-gated ion channels open and close in response to what?

Answer 10

changes in the membrane potential

Question 11

stimulation of a neuron causes what?

Answer 11

local disturbances in membrance potential

Question 12

local potential is what kind of change in voltage?

Answer 12

short-range

Question 13

four characteristics what distinguish a local potential

Answer 13

graded
decremental
reversible
excitatory

Question 14

graded varies in

Answer 14

magnitude according to the strength of the stimulus

Question 15

decremental gets weaker

Answer 15

as they spread from the point of origin

Question 16

reversible if the stimulation

Answer 16

ceases

Question 17

diffusion out of the cell quickly returns the membrane voltage to its resting potential

Answer 17

reversible

Question 18

excitatory

Answer 18

polarize a cell and make a neuron more likely to produce an action potential

Question 19

step one of action potential

Answer 19

arrival of local potentials at axon hillock depolarizes membrane

Question 20

step two of action potential

Answer 20

depolarization must reach threshold
critical voltage required to open voltage-regulated gates

Question 21

step three of action potential

Answer 21

Voltage-gated Na+ channels open, Na+ enters and depolarizes cell
Opens more channels resulting in rapid positive feedback cycle as voltage rises

Question 22

in step three an action potential

Answer 22

is produced

Question 23

step four of action potential

Answer 23

Na+ channels are inactivated and close
Voltage peaks
Membrane polarity is reversed

Question 24

step 5 of action potential

Answer 24

Slower-voltage gated K+ channels open
Outflow of K+ repolarizes cell

Question 25

step 6 of action potential

Answer 25

K+ channels remain open for a time
Membrane briefly hyperpolarized
More negative than RMP

Question 26

step 7 of action potential

Answer 26

RMP restored as all voltage-gated channels go back to closed states
Na+ leaks into cell
K+ leaks out of cell
Sodium-potassium pump keeps working

Question 27

in the all-or-none law action potential will occur when a

Answer 27

stimulus reaches the threshold

Question 28

in an all-or-none law, if a stimulus depolarizes the neuron to threshold,

Answer 28

the neuron fires at its mox voltage

Question 29

with distance, nondecremental

Answer 29

do not get weaker

Question 30

in a nondecremental, the last action potential at the end of a nerve fiber is

Answer 30

just as strong as the first one in the trigger zone

Question 31

in irreversible, if a neuron reaches threshold, the action potential

Answer 31

goes to completion

Question 32

irreversible cannot be stopped

Answer 32

once it begins

Question 33

refractory period is a period of time after a nerve or muscle cell

Answer 33

has not responded to a stimulus in which is cannot be re excited by a threshold stimulus

Question 34

in an absolute refractory period no stimulus of any strength

Answer 34

will trigger a new potential

Question 35

in a relative refractory period is it possible to

Answer 35

trigger a new action potential, but only with an strong stimulus

Question 36

if an axon is unmyelinated

Answer 36

continuous conduction

Question 37

continuous conduction is the uninterrupted

Answer 37

wave of electrical excitation all along the fiber

Question 38

in myelinated axons, an action potential at one node of ranvier causes

Answer 38

an action potential in the next node

Question 39

myelinated axons perform

Answer 39

saltatory conduction

Question 40

saltatory conduction creates

Answer 40

jumping or leaping

Question 41

saltatory conduction cannot conduct a signal in continuous mode because

Answer 41

voltage-gated ion channels are too scarce in the myelin-covered internodal segments

Question 42

myelinated axons are ____________ than unmyelinated axons

Answer 42

much faster