4 - Nervous 1 : Membrane Potential

Front 1

gradient

Back 1

As used here, the gradual continuous increase or decrease in solute concentration from one region to another.

Front 2

membrane potential

Back 2

The electrical potential, or voltage, across a cell membrane that results from the separation of charged particles across the membrane.

Front 3

Na+ - outside
K+ - inside
CI- - outside

Back 3

Which of these ions have a high concentration outside the cell and which have a high concentration inside the cell? Na+, K+, Cl-

Front 4

through ion channels

Back 4

What is the only way that ions can get across the cell membrane?

Front 5

it lets certain ions through, but prevents others from crossing

Back 5

What does it mean to say that cells exhibit selective permeability with respect to ions.

Front 6

K+

Back 6

Which ion are most cells in the body permeable to?

Front 7

They are selectively permeable towards ions

??

Back 7

How do neurons differ from most of the other cells in the body with respect to ion permeability?

Front 8

Excitable cells are very permeable to potassium & slightly permeable to sodium.

Back 8

What's the difference between a neuron's permeability to sodium and potassium?

Front 9

1. # of channels
2. the ease w/which the ion can move through that channel

Back 9

What two factors will affect the permeability of a cell for a particular ion?

Front 10

gated channels

Back 10

What mechanism used by the nervous system to produce rapid changes in membrane permeability?

Front 11

K+

Back 11

As opposed to neurons, simple, non-excitable cells are permeable only to one ion. What is that ion?

Front 12

gradient (high to low concentrations)

Back 12

What major factor causes ions to move through ion channels?

Front 13

a chemical force

Back 13

What type of force is the concentration gradient?

Front 14

When ions move out of the cell, it makes more + outside, and more - inside.

Back 14

How does the cell membrane become more positive outside and more negative inside?

Front 15

electrical potential (voltage)

Back 15

What type of force is the separation of charge?

Front 16

+
-
diffuse ?

Back 16

As potassium diffuses out of a cell, the outside of the cell becomes more _______ and the inside of the cell becomes more ________. Since opposite charges attract each other, and potassium is positive, the potassium will __________.

Front 17

electrical potential

Back 17

The force that is responsible for the movement of positive potassium ions back into the cell, where it is more negative is called the _________.

Front 18

electrical potential
voltage

Back 18

What are two alternative names for the electrical force?

Front 19

1. the concentration gradient or chemical force
2. The electrical potential (force)

Back 19

What are the two parts of the electrochemical gradient?

Front 20

chemical force causes K+ to diffuse out of the cell.

electrical force pulls K+ back into the cell.

Back 20

.) What effect does both the chemical force and the electrical force have on K+?

Front 21

when K+ is at equalibrium

Back 21

When is there no net movement of K+ across a membrane?

Front 22

Yes

Back 22

When there is no net movement, does that mean that ions are not moving across the membrane?

Front 23

What is a membrane potential?

Back 23

The electrical potential or voltage, across a cell membrane that results from the sep. of charged particles across the membrane.

Front 24

millivolts

Back 24

In what units is both the concentration and the membrane potential measured?

Front 25

-90mV

Back 25

What is the equilibrium potential in general?

Front 26

150mM K+ inside and 5mM K+ outside. This means that K+ is equal and opposite when the membrane potential is 90 mV.

Back 26

What is the equilibrium potential for K+ in a non-excitable cell? What does this mean?

Front 27

Chemical force pull Na+ into the cell, because it has a net neg. charge K+ in the cell. Wants to pull Na+ into the cell. Electrical force pulls Na+ into cell, because the charge sep. acts as the force.

Back 27

Neurons are slightly permeable to sodium ions. a. In which direction is the chemical force for sodium? Why? b. In which direction is the electrical force for sodium? Why?

Front 28

The electrical potential & chemical potential. It pulls Na+ into the cell.

Back 28

What is the electrochemical gradient for sodium a combination of ? In which direction is the electrochemical gradient for sodium?

Front 29

Ty means that the neuron is at rest. A typical value is -70mV.

Back 29

What does the term "resting membrane potential" in a neuron mean. What is a typical value for the resting membrane potential.

Front 30

The non-excitable cells only depend on K+. K+ comes to equalibrium when membrane potential is -90mV. The resting membrane potential depend ob both Na+ and K+ across cell membrane.

Back 30

Why do non-excitable cells have a membrane potential of -90 mV while neurons have a resting membrane potential of -70 mV?

Front 31

Because the chemical force out of the cell is greater than the electical force back into the neuron.

Back 31

.) At -70 millivolts, the resting membrane potential, why does potassium leak out of the neuron?

Front 32

Because the force is very large, but neuron only slightly is permeable to Na+.

Back 32

At -70 millivolts, the resting membrane potential, why does sodium slowly leak into the neuron?

Front 33

K+/Na+ pump

Back 33

What compensates for the leakage of sodium and potassium ions?

Front 34

against their chemical gradients

Back 34

Does the sodium-potassium pump move sodium and potassium with or against their gradients?

Front 35

ATP

Back 35

What provides the energy to pump sodium and potassium against their gradients?

Front 36

3
2

Back 36

The sodium-potassium pump pumps out ______ sodiums for every _____ potassiums that are pumped in.

Front 37

It maintains Na+ & K+ leaks

Back 37

How does the sodium-potassium pump keep the resting membrane potential at -70 millivolts.

Front 38

B

Back 38

The sodium–potassium pump ___________.
a. creates the membrane potential
b. maintains the membrane potential

Front 39

concentration gradient

Back 39

The difference in the concentration of a particular substance between two adjacent areas.

Front 40

electrical potential

Back 40

An electrical force across a cell membrane that results from the separation of charged particles across that membrane.

Front 41

electrochemical gradient

Back 41

The combined electrical and chemical forces on an ion. This force determines the net movement of charged particles.