Lecture 5

Question 1

What does cell polarization mean?

Answer 1

A difference in electrical charge between in inside and outside of cell.

Question 2

When is a cell polarized?

Answer 2

At rest; the inside of the cell is negative

Question 3

What is the normal polarity of a cell at rest?

Answer 3

About -80; negative

Question 4

What is depolarization?

Answer 4

Happens during an action potential; when the cell is stimulated/turned on; the cell becomes more positively charged which is less polar.

Question 5

What is hyperpolarization?

Answer 5

Happens during/after repolarization; Cell polarity becomes more negative than the resting cell polarity.

Question 6

What happens when a cell is more negatively charged?

Answer 6

Cell becomes more difficult to excite

Question 7

What is repolarization?

Answer 7

Happens after depolarization when you return back to V(rm); anything that makes the cell more negative after an action potential.

Question 8

What happens during depolarization?

Answer 8

Sodium channels open and rushes into the cell and pNa+ increases; membrane potential will become closer to Nernst for Na+

Question 9

What happens during hyperpolarization?

Answer 9

Increase in potassium channels opening; Membrane potential becomes even closer to Nerst for K+; Deals with the AV node in the heart.

Question 10

What happens to the cell when the polarity of the cell goes above 0?

Answer 10

The Na+ channels are opening and the cell becomes more permeable to Na+ than K

Question 11

What is happening during repolarization?

Answer 11

Na+ channels are closing and the K+ channels are opening

Question 12

Why does hyperpolarization happen?

Answer 12

It is a result for the slowly closing K+ channels

Question 13

What contributes the membrane potential?

Answer 13

Leaky K+ and Na+ channels

Question 14

What drugs affect the V-G Na+ Channels and how?

Answer 14

-caine

Affects the activation gate of sodium channels

Question 15

At rest, the activation gate for Na+ channels are_____

Answer 15

Closed

Question 16

What are 2 traits of the Na+ channels?

Answer 16

Fast and highly selective

Question 17

What is the M-gate? Where is it located?

Answer 17

Activation gate

On the outside of cell

Question 18

What is H-gate? Where is it located?

Answer 18

Inactivation gate

On the inside of cell

Question 19

Describe a Na+ channel in a resting cell?

Answer 19

The M-gate is closed and the H-gate is open

Question 20

Describe a Na+ channel in an activated cell?

Answer 20

Both M- and H- gates are open but H- gate will close immediately; Na+ will flood into cell for a short period of time

Question 21

Why does the resetting of ion channels need to be quick?

Answer 21

To get ready for another action potential; especially important in the heart

Question 22

Describe a Na+ channel in repolarization?

Answer 22

The channel will go from having the H gate closed;

The M- gate will close

The H gate will open; process starts over. Na+ channel ready for another action potential

Question 23

Describe a K+ channel during rest.

Answer 23

The gate is closed

Question 24

Describe a K+ channel during activation?

Answer 24

The K+ channel gate slowly open

Question 25

Describe a K+ channel

Answer 25

Only has 1 gate; the gate opens AND closes slowly

Question 26

What does V-G mean?

Answer 26

Voltage gated

Question 27

What is the purose of K+ channels?

Answer 27

Help speed up repolarization

Question 28

What is the difference between K+ and Na+ channels?

Answer 28

K+ channels only has 1 gate and opens slower than Na+ channels. The Na+ channel has 2 gates and opens and closesly quickly.

Question 29

What happens when your cell membrane is off?

Answer 29

It can affect how fast we can reset our fast Na+ channels therefore the next action potential will be slower.

Ex) In hyperkalemia the HR will decrease

Question 30

Describe the action potential in the heart?

Answer 30

It plateaus. The action potential is sustained for a long time.

Question 31

Driving force depends on what 3 things?

Answer 31

1. Charge of the ion
2. Concentration gradient
3. Charge inside the cell

Question 32

What does equilibirum potential mean?

Answer 32

Charge thats required on the inside of the cell to prevent the net movement of that ion down its concentration gradient; no net movement into cell

Question 33

What happens when your membrane potential is equal to your ion permeability?

Answer 33

The ion will not move down its concentration gradient

Question 34

What happens when your membrane potential is more/less than your ion permeability?

Answer 34

The cell will push the ion in the opposite of its concentration gradient

Question 35

What does driving force mean?

Answer 35

Motivation to go into the cell

Question 36

What is a common cardiac rhythm you see with hyperkalemia?

Answer 36

V-fib