Exam 2 Powerpoint 8

Question 1

Sodium potassium pump

Answer 1

3 Na + out 2K+ in

Question 2

In neurons, how does the
increase in sodium permeability
occur during the Action
Potential?

Answer 2

Voltage gated sodium channels, open at threshold

Question 3

Voltage gated K channels are important at

Answer 3

falling phase

Question 4

Is permeability voltage dependent?

Answer 4

yes

Question 5

Inward current

Answer 5

Early
Transient(comes and goes)
Fast
Na+

+ charge enters

Question 6

Outward current

Answer 6

Late
Sustained
Delayed
Slow
K+

+ charge leaves

Question 7

Current flow across a membrane is sensitive to

Answer 7

membrane voltage

Question 8

There are____different types of voltage dependent ion currents

Answer 8

2

Question 9

How could researchers tell that Na+ and K+ were responsible

Answer 9

they changed to concentration of those ions

Question 10

TTX (tetrodotoxin)

Answer 10

Puffer fish, skin of frogs, and salamanders

Blocks Na+ channels

Question 11

TEA: tetraethylammonium

Answer 11

Large organic cation

Blocks K+ channels

Question 12

The solutions of the body (solution inside and outside cells)
are ____________, and they will therefore conduct electricity

Answer 12

ionic solutions

Question 13

Membrane potentials are voltages, which ______________ made
up of the movement of ions

Answer 13

drive currents

Question 14

Ions can cross membranes through ion channels, the resistance being smaller the _______________________

Answer 14

more channels are open

Question 15

We can therefore use Ohm’s law to predict how much current
would flow when the ion channels opened, if we knew the
_____________- (the voltage across the membrane) and
the ___________ of the membrane to the passage of the ions.

Answer 15

membrane potential
resistance

Question 16

Number of open channels is called ____________

Answer 16

permeability

Question 17

Vdf=

Answer 17

Vdf= (Vm – Erev)

Question 18

Iion =

Answer 18

Iion = gion * (Vm – Erev)

Question 19

There are two factors for an ion
that determine how much influence that ion will have over the membrane potential of a cell

Answer 19

◦ That ion’s driving force and,
◦ That ion’s permeability

Question 20

A positive driving force (i.e., VDF > 0) predicts ion movement ___________________

Answer 20

out of the cell

Question 21

A negative driving force (i.e., VDF < 0) predicts ion movement _______________

Answer 21

into the cell