Action Potential

Question 1

The membrane potential depends on

1) _____
2) _____
3) _____

Answer 1

the concentration gradient
the electrical driving force
the relative permeability of the membrane for a given ion

Question 2

Permeability for an ion (P) or conductance
• many channels open = high _____
• many channels closed = high _____

Answer 2

conductance

resistance

Question 3

At rest, Vm (resting potential) is primarily determined by _____ distribution.

Answer 3

K+

Question 4

The Goldman Equation describes _____ in an environment with _____. It takes into account the _____ of each ion

Answer 4

equilibrium
more than one ion
relative permeability (P)

Question 5

Cells vary permeability of membrane by _____.

Answer 5

opening/closing channels

Question 6

Membrane potential can be changed by altering _____.

Answer 6

permeability

Question 7

An action potential is the result of _____ increasing a cell’s permeability to ___ and ___.

Answer 7

increasing
Na+
K+

Question 8

The threshold of an action potential occurs at __ mV.

Answer 8

-55 mV

Question 9

The overshoot of an action potential occurs at __.

Answer 9

X > 0 mV

Question 10

Afterhyperpolarization / Undershoot occurs at __ mV.

Answer 10

X < -60 mV

Question 11

An action potential is the result of selective (voltage- and time-dependent) _____ in the membrane’s permeability to ___ and ___.

Answer 11

increases
Na+
K+

Question 12

The voltage clamp allows the membrane voltage to be manipulated independently of the _____, allowing the _____-_____ relationships of membrane channels to be studied.

Answer 12

ionic currents
current
voltage

Question 13

Hodgkin and Andrew Huxley used the voltage clamp to outline ______.

Answer 13

the ionic mechanisms that underlie the action potential

Question 14

The voltage clamp provides a measure of _____ in the membrane.

Answer 14

the membrane current passing through ion channels

Question 15

The direction of current flow is defined as _____ of ______.

Answer 15

net movement

positive charge

Question 16

Flow of _____ is defined as inward current.

Answer 16

positive charge into the cell

or negative charge out of the cell

Question 17

Na+ flowing into the cell along its concentration gradient brings more _____ into the cell, creating a(n) ______.

Answer 17

positive charge

inward current

Question 18

K+ flowing out of the cell taking its _____ charge with it creates a(n) _____.

Answer 18

positive

outward current

Question 19

Current-clamp experiments depict the change of the _____.

Answer 19

membrane potential

Question 20

Early inward current reverses at potentials more depolarized than _____.

Answer 20

E-(sub)-Na

Question 21

The equilibrium potential is the potential at which the _____ offsets the movement of an ion due to its _____.

Answer 21

electrical force

concentration gradient