3 - Nervous System 1: Action Potential

Front 1

E - hyperpolarization
B - depolarization
A - rest
C - initiation of repolarization
D - repolarization

Back 1

Which part of the graph to the right corresponds to the following:
hyperpolarization
depolarization
rest
initiation of repolarization
repolarization

Front 2

D

Back 2

Which part of the graph to the right corresponds to:
A time when voltage-gated sodium channels are inactivated, then reset to the closed state. Potassium channels continue to open.

Front 3

A

Back 3

Which part of the graph to the right corresponds to:

A time when voltage-gated sodium and potassium channels are closed.

Front 4

C

Back 4

Which part of the graph to the right corresponds to:

A time when voltage-gated sodium channels begin to inactivate and voltage-gated potassium channels begin to open.

Front 5

B

Back 5

Which part of the graph to the right corresponds to:

A time when voltage-gated sodium channels open rapidly, resulting in movement of sodium into the cell.

Front 6

A. rest

Back 6

Which phase of the action potential does the diagram below best correspond to?
a. rest
b. depolarization
c. peak
d. repolarization
e. hyperpolarization

Front 7

A. rest

Back 7

Which phase of the action potential does the diagram below best correspond to?
a. rest
b. depolarization
c. peak
d. repolarization
e. hyperpolarization

Front 8

C. Peak

Back 8

Which phase of the action potential does the diagram below best correspond to?
a. rest
b. depolarization
c. peak
d. repolarization
e. hyperpolarization

Front 9

D. repolarization

Back 9

Which phase of the action potential does the diagram below best correspond to?
a. rest
b. depolarization
c. peak
d. repolarization
e. hyperpolarization

Front 10

E. hyperpolarization

Back 10

Which phase of the action potential does the diagram below best correspond to?
a. rest
b. depolarization
c. peak
d. repolarization
e. hyperpolarization

Front 11

B

Back 11

What letter on this graph to the right corresponds to the absolute refractory period?

Front 12

C

Back 12

What letter on this graph to the right corresponds to the relative refractory period?

Front 13

nerve impulse

Back 13

What is another name for an action potential?

Front 14

A large membrane potential change

Back 14

What does an action potential consist of?

Front 15

axon hillock

Back 15

Where is the action potential generated?

Front 16

when it receives signals from dendrites & the cell body.

Back 16

What causes an axon potential to occur at the axon hillock?

Front 17

They open rapidly to increase permeability to Na+

Back 17

What happens to ion channels when the membrane depolarizes at the axon hillock?

Front 18

15 mV

Back 18

How much does the axon hillock have to depolarize to reach threshold?

Front 19

threshold

Back 19

An action potential is generated.

Weak stimuli that DO NOT reach _________ do no produce action potentials. The action potential is an "all or none" event.

Front 20

the action potential is NOT produced.

Back 20

What happens if there is a weak stimulus at the axon hillock and threshold is not reached?

Front 21

yes

Back 21

Do action potentials always have the same amplitude and the same duration?

Front 22

This means a positive feedback loop is established.

Back 22

Threshold is a special membrane potential where the process of depolarization becomes regenerative. What does this mean?

Front 23

It opens more Na+ voltage-gated channels

Back 23

What happens to sodium voltage-gated channels at threshold?

Front 24

The more Na+ flow into the cell causes the cell to depolarize further and open more Na+ voltage-gated channels.

Back 24

Explain how the positive feedback loop maintains the rising phase of the action potential.

Front 25

1. Inactivation of Na+ voltage-gated channels
2. The opening of voltage gated K+ channels

Back 25

The rising phase of the action potential ends when the positive feedback loop is interrupted. What two processes break the loop?

Front 26

1. voltage-sensitive gatd
2. time-sensitive inactivation gate

Back 26

What are the names of the two gates on the voltage-gated sodium channels?

Front 27

When the cell is depolarized

Back 27

When does the voltage-sensitive gate open?

Front 28

it stops the movement of Na+ through the channel after the channel has been open for a fixed time.

Back 28

What is the function of the time-sensitive inactivation gate?

Front 29

They begin to inactivate the inward flow of Na+ decreases, and positive feedback loops are interupted.

Back 29

What happens to the voltage gated sodium channels at the peak of the action potential?

Front 30

when action potential reaches it peak

Back 30

When do the voltage-gated potassium channels open?

Front 31

depolarization ends and positive feedback loop is interupted.

Back 31

What happens when the voltage-gated potassium channels open and the potassium moves out of the cell?

Front 32

When Na+ moving into the and more K+ moving out of the cell.

Membrane pot. becomes more -, moving toward the resting value.

Back 32

When does repolarization occur? What happens to the membrane potential?

Front 33

hyperpolarization

Back 33

Process by which the membrane potential of a cell changes to become more - than its resting membrane potential.

Front 34

Because K+ keeps moving out of the cell, making it -.

Back 34

Why does hyperpolarization occur?

Front 35

B. During the rising phase of the action potential

Back 35

During the action potential, when does sodium permeability increase rapidly?

a. during repolarization
b. during the rising phase of the action potential
c. during hyperpolarization
d. during repolarization

Front 36

A. during repolarization

Back 36

During the action potential, when does sodium permeability decrease rapidly?

a. during repolarization
b. during the rising phase of the action potential
c. during hyperpolarization
d. during repolarization

Front 37

a. during repolarization

Back 37

During the action potential, when is potassium permeability the greatest?

a. during repolarization
b. during the rising phase of the action potential
c. during hyperpolarization
d. during repolarization

Front 38

C. during hyperpolarization

Back 38

During the action potential, when does potassium permeability decrease slowly?


a. during repolarization
b. during the rising phase of the action potential
c. during hyperpolarization
d. during repolarization

Front 39

C. the rising phase of the action potential

Back 39

The rapid increase in sodium permeability is responsible for _____.

a. the repolarization of the cell
b. the hyperpolarization
c. the rising phase of the action potential

Front 40

A. the repolarization of the cell

Back 40

The rapid decrease in sodium permeability and simultaneous increase in potassium permeability is responsible for _____.

a. the repolarization of the cell
b. the hyperpolarization
c. the rising phase of the action potential

Front 41

B. The hyperpolarization

Back 41

The slow decline in potassium permeability is responsible for _____.
a. the repolarization of the cell
b. the hyperpolarization
c. the rising phase of the action potential

Front 42

absolute refractory period

Back 42

The period of time following an action potential when an excitable cell cannot generate another action potential no matter how large a stimulus it receives.

Front 43

Because Na+ can't move in through inactive channels & because K+ continues to move through open voltage gated channels.

Back 43

Why can't a neuron generate another action potential during the absolute refractory period?

Front 44

relative refractory period

Back 44

The period of time following an action potential when an excitable cell can generate another action potential only if it receives a stimulus stronger than normal.

Front 45

It is more difficult because it has to be depolarized to a value more positive than normal threshold.

Back 45

Why is it more difficult for a neuron to generate another action potential during the relative refractory period?

Front 46

1. the diameter of the axon
2. How well the axon is insulated w/myelin.

Back 46

What two factors does conduction velocity depend on?

Front 47

As the axon diameter increases, the internal resistance to the flow of charge decreases
The potential travels faster.

Back 47

What is the effect of axon diameter on conduction velocity?

Front 48

It makes the action potential travel faster down the axon.

Back 48

What is the effect of myelin on conduction velocity?

Front 49

More speed is gained by insulating an axon w/myelin than by increasing the axon diameter.

Back 49

Why do myelinated axons conduct action potentials faster than non myelinated axons?

Front 50

it is propogated down the axon

Back 50

What happens after an action potential is generated at the axon hillock?

Front 51

+ charges flow along axon
depolarizing adjacent areas of membrane
reaches the threshold
generate an action potential (which moves along the axon as a wave of depolarization traveling away from the cell body.)

Back 51

How is an action potential propagated down the axon?

Front 52

conduction velocity

Back 52

The speed with which an action potential is propagated along an axon.