10/12 Action Potentials - Roger 2017

Question 1

Define Polarization? 7

Answer 1

any deviation from the equilibrium potential from 0mv

Question 2

Define depolarization? 8

Answer 2

Membrane potential becomes more positive

Question 3

Define Hyperpolarization? 7

Answer 3

Membrane potential becomes more negative

Question 4

Define Repolarization? 9

Answer 4

Membrane potential returning to resting membrane potential

Question 5

What is the time interval for a motor neuron, skeletal muscle, and cardiac ventricle action potential? 10

Answer 5

Motor neuron —> 2 ms

Skeletal muscle —> 5 ms

Cardiac ventricle —> 200 ms

Question 6

What are the key properties of action potentials? 11

Answer 6

PAN

P ropagated or self-reinforcing
A ll-or-none
N on-decremental

Question 7

What are the characteristics of graded potentials? 12

Answer 7

Small/local changes in membrane potential

Dissipates with distance

Question 8

What is the resting phase? 15

Answer 8

Phase 4

Question 9

What phase is Depolarization (-90mv —> +30mv)

Answer 9

Phase 0

Question 10

What phase is repolarization? 15

Answer 10

Phase 3

Question 11

What else do we refer to hyperpolarization as during an action potential? 15

Answer 11

Refractory period

Question 12

What occurs during depolarization of an action potential? 19

Answer 12

Increased permeability of membrane to Na+

Voltage-gated Na+ open rapidly

Channels close automatically almost as soon as they open

Question 13

What are the two gates of the voltage-gated Na+ channel? 20

Answer 13

Activation gate

Inactivation gate

Question 14

Prior to potential what is the condition of the gates of the voltage-gated Na+ channels?

Answer 14

Inactivation gate is open

Activation gate is closed

Question 15

At the commencement of the action potential was is the condition of the gates of a voltage-gated Na+ channel? 20

Answer 15

Inactivation gate is open (still)

activation gate opens (previously closed)

Question 16

After the initiation of the action potential was is the condition of the gates of the voltage-gated Na+ channels? 20

Answer 16

Inactivation gate now closes (previously open)

Activation gate remains open

Question 17

Slide 20

Answer 17

Listen to recording

Question 18

Slide 21

Answer 18

Listen to recording

Question 19

Slide 22

Answer 19

Listen to recording

Question 20

What are the key characteristics of Voltage-gated K+ channels? 23

Answer 20

Selectivity (an ability to close)

Question 21

24

Answer 21

Listen to recording

Question 22

25

Answer 22

Draw out:
Gates open/closed
What each phase is

Question 23

Describe the absolute refractory period? 26

Answer 23

Na+ channels are either open or the inactivation gate is closed

Incapable of reopening (protects the cell)

Question 24

Describe Relative refractory period? 26

Answer 24

Inactivation gate is open
Activation gate is closed

Action potential can be initiated but it requires a stronger stimulus

Question 25

What occurs exactly at threshold potential? 28

Answer 25

Add

Question 26

What occurs once threshold is reached? 31

Answer 26

Add

Question 27

32- 34

Answer 27

Listen to recording

Question 28

What occurs in Hypokalemic Periodic Paralysis (HypoPP)? 35

Answer 28

Periodic (but not always) dips in blood K+

Membrane hyperpolarized and therefore harder to reach threshold

Repolarization occurs more quickly

Question 29

What occurs in Hyperkalemic Periodic Paralysis? 37

Answer 29

Add

Question 30

38

Answer 30

ADD