Chapter 2 Resting potential Flashcards Preview

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Flashcards in Chapter 2 Resting potential Deck (55)
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1

simply a device that separates positive and negative
charges

battery

2

The separation of charges
is due to two major things. Please enumerate

First is that there is an imbalance of various ions on the inside compared to the outside
of the cell.

Inside, more K
Outside, more Na

Second is that the cell membrane is semipermeable

3

simply means that
the membrane has pores or channels that allow only certain molecules to pass while preventing
others from crossing from one side to the other.

Semipermeable

4

The semipermeable membranes of all cells
allow _____ ions to pass through easily

K+ ions

5

The semipermeable membranes of all cells
allow K+ ions to pass through easily, but act as barriers for the passage of

Na+, Cl-, and Ca++ ions.

6

law of diffusion

that all molecules move
from a region of higher concentration to a region of lower concentration, and will continue to do
so until the concentrations become equal throughout.

7

In other words, there are
two opposing forces acting on K+ ions;

the concentration force driving K+

electrical force driving K

8

In other words, the net movement of K+ across the membrane will cease when

the two
opposing forces acting on K+ are equal

9

ccurs when the
concentration force tending to drive K+ from left to right is exactly balanced by the electrical force
tending to attract K+ from the right back into the left compartment.

equilibrium

10

This electrical force, or
electrical potential, that counterbalances the concentration force is called the

equilibrium potential for that ion.

11

the greater the
concentration difference for the permeable ion, K+ in this case, the more _____ the left
compartment has to be to counteract the concentration force

more negative

12

is a statement of the equilibrium condition for a single ion species
across a membrane that is permeable only to that ionic species.

Nernst Equation

13

Nernst equation tell you

what electrical force (electrical potential E in equation below) has to act on that ion in
order to exactly balance the concentration force acting on the same ion.

14

The E in the Nernst equation is referred to as the

equilibrium
potential for the ion

15

is the potential at which equilibrium is attained

equilibrium
potential for the ion

16

Cell membranes are impermeable to large organic anions existing inside the
cell, such as

aspartate, isothionate, and other amino acids as well as proteins

17

All Cells have a Resting Potential Determined Largely by

Potassium

18

Nernst Equation is

58/z log (ion ouside/ ion inside)

19

in squit, K+ concentration in the interstitial
(extracellular) fluid is

20 mM

20

squid : K+ concentration inside the cell

400 mM.

21

The actual resting potential of the squid giant axon can be accurately measured and is only
about

-70 mV.

22

is the electrical state of the cell (the voltage across its
membrane) when it is not active and thus not generating action potentials.

resting membrane potential

23

The reason that the actual resting potential of the cell is not equal to Ek is that

both Na+ and
Cl- play a small role in determining the electrical state of the cell (the cell's resting potential).

The membrane is not absolutely impermeable to Na+.

24

force/s that drive Na into the cell

concentration
and electrical forces

25

[Na]o

450 mM

26

[Na]i

50 mM

27

ENa

+55 mv

28

Ek,

-70 mV

29

Based on
concentrations of Cl-, the Nernst equation tells us that the equilibrium potential for Cl-

-67 mV

30

The Concentration Gradients of All Ions Should Run Down but the cell has a means to combat this problem which is

it has sodium-potassium pumps.