6.1 Membrane Potentials

Question 1

All cells have membrane potential which is

Answer 1

The difference in charge across a membrane

Question 2

Sodium, Potassium ATPase moves

Answer 2

Three Sodium 2+ ions out and
two Potassium + ions in

Question 3

examples of negatively charged ions in the cell

Answer 3

DNA, proteins

Question 4

Difference in charge across a membrane can be measured using a

Answer 4

Voltmeter

Question 5

More positive charge found _____ and less positive (more negative) charge found ______.

Answer 5

Outside, inside

Question 6

Inverting the membrane potential is known as creating

Answer 6

Action potential

Question 7

Action potential is known as

Answer 7

Work being done

Question 8

Which cells can create action potential (converting membrane potential)

Answer 8

Excitable tissues (nervous and muscle)

Question 9

RMP

Answer 9

Resting membrane potential

Question 10

A neurons RMP is around

Answer 10

-70 mv

Question 11

Depolarization is when

Answer 11

The cell becomes less negative (more positive)

Question 12

Hyper-polarization is when

Answer 12

The cell becomes more negative (less positive)

Question 13

Voltage gated Na+ channel

Answer 13

• open at approx -55mv
• allow sodium in
• quick to respond

Question 14

Voltage gated K+ channel

Answer 14

• open at approx 30mv
• potassium will go out
• slower to respond

Question 15

After -55mv threshold is reached what happens

Answer 15

Depolarization: Charge jumps to 30mv (positive) because sodium channels opened.
Then, when the sodium channels close, the potassium channels open causing potassium to flow out (Less positive in the cell aka hyper polarization). Drops to -70 - -90 mv.

Question 16

After the depolarization and hyper polarization, what happens

Answer 16

The -70 mv gradient is re-established by the sodium potassium atpase pump

Question 17

Steps of action potential

Answer 17

1. RMP -70mv
2. Excitable stimulus
3. Threshold reached -55mv
4. Voltage gated Na+ channel opens
5. Depolarization
6. Na+ channels close (+30mv)
7. K+ channels open, re-polarization
8. Hyper polarization (goes beyond -70)
9. K+ channels close
10. Na+/K+ ATPase returns RMP

Question 18

Absolute refractory period is

Answer 18

When you cannot have another action potential occur (channels already open can’t open again or further)

From the threshold point to the RMP (before hyperpolarization)

Question 19

Relative refractory period

Answer 19

From after the absolute refractory period to when RMP is re-established (all of the hyper polarization bit) Hard to stimulate but you can.