Chapter 6 & 7

Question 1

What is the normal resting potential of a cell

Answer 1

-65 to -70 mV

Question 2

What measures the resting potential of a cell

Answer 2

Oscilloscope

Question 3

How does the oscilloscope measure the resting potential

Answer 3

One probe is in the intracellular fluid and the other is in the extracellular fluid

Question 4

What are the major players in membrane and action potentials (5)

Answer 4

1. K+
2. Na+
3. Cl-
4. Ca++
5. Proteins (A-)

Question 5

Which of the major players are in greater concentration inside the cell (2)

Answer 5

1. K+

2. A-

Question 6

Which of the major players are in greater concentration outside the cell (3)

Answer 6

1. Na+
2. Cl-
3. Ca++

Question 7

What is equilibrium potential

Answer 7

A balance between diffusion and electrostatic pressure

Question 8

What is the equation used to determine the equilibrium potential

Answer 8

Nernst equation

Question 9

What is the Nernst equation

Answer 9

V= RT/zF ln([X]out/[X]in)

Question 10

What is R

Answer 10

Gas constant 8.314

Question 11

What is T

Answer 11

Temperature 298.15K (room temp)

Question 12

What is F

Answer 12

Faraday’s constant 96500

Question 13

What is z

Answer 13

Charge of ion

Question 14

What are glial cells permeable to at rest

Answer 14

K+ only

Question 15

What are neurons permeable to at rest

Answer 15

Na+ and K+

Question 16

How many open channels are there for K+ and Na+ in a neuron (roughly)

Answer 16

K+: Many open channels

Na+: Only a few open channels

Question 17

What does the Na+/K+ pump move

Answer 17

3 Na+ out and 2 K+ in

Question 18

What is a graded potential

Answer 18

The stimuli is able to vary in size from small to big

Question 19

What does depolarization at the dendrites give you

Answer 19

Only graded potentials

Question 20

What does depolarization at the axon hillock/axon give you

Answer 20

Only action potentials

Question 21

True or False:

A graded potential diffuses to nearby areas and leaks out of the neuron as it moves down the neuron

Answer 21

True

Question 22

Where does the signal need to go in order to initiate an action potential

Answer 22

Axon hillock

Question 23

What is an action potential

Answer 23

A nerve impulse that is an electrical signal that moves from the axon hillock down the axon to the terminal button

Question 24

What is it called when you send a signal from the axon hillock to the terminal button

Answer 24

Internal neuronal communication

Question 25

What are the 4 properties of an action potential

Answer 25

1. Threshold 2. All-or-none 3. Does not diminish 4. Followed by refractory period

Question 26

What is the threshold

Answer 26

The point at which an AP will occur when the graded potential is big enough

Question 27

What is all-or-none

Answer 27

When the threshold is met the action potential will be the same but if the threshold isn't met no action potential is formed

Question 28

True or False: | The action potential is the exact same at the start and end of the axon

Answer 28

True

Question 29

What is the refractory period

Answer 29

Time during which an AP can't occur or it is much harder to get an AP

Question 30

What are 2 critical voltage gated channels for causing an AP

Answer 30

1. Na+ | 2. K+

Question 31

What happens when there is a conformational change in the voltage gated channel

Answer 31

An action potential occurs

Question 32

What causes a conformational change in the voltage gated channel

Answer 32

Positively charged amino acids moving inside the voltage gated channel do to a big enough graded potential

Question 33

What are 2 key differences between the Na+ and K+ voltage gated channels

Answer 33

1. Na+ channel opens faster | 2. Na+ channel becomes inactivated

Question 34

When are the Na+ channels deactivated based on the graph

Answer 34

At the peak of the graph

Question 35

What close the voltage gated Na+ channels

Answer 35

The ball and chain

Question 36

What prevents the neuron from getting to +55 mV which is the equilibrium potential of Na+

Answer 36

K+ prevents it

Question 37

What occurs once the Na+ channels close

Answer 37

K+ continues to leave the cell bringing the cell back to it's negative potential

Question 38

What causes the over shoot

Answer 38

The remaining K+ outside the cell makes the inside of the cell negative making it briefly hyperpolarized

Question 39

What are the 6 steps of an action potential firing

Answer 39

1. Na+ channels open and Na+ begins to enter the cell 2. K+ channels open K+ begins to leave cell 3. Na+ channels close so no more Na+ enters the cell 4. K+ continues to leave the cell bringing the membrane potential back to normal 5. K+ channels close and Na+ channels reset 6. Extra K+ outside diffuses away

Question 40

What is the absolute refractory period

Answer 40

The period of time following an action potential during which no stimulus can initiate another action potential

Question 41

What mediates the absolute refractory period

Answer 41

The Na+ channels being inactivated by the ball and chain

Question 42

What is the relative refractory period

Answer 42

The period of time following an action potential during which an action potential can be initiated but only by a stronger than normal stimulus

Question 43

When does the relative refractory period occur

Answer 43

When the Na+ channels are de-inactivated (ball and chain is no longer closing channel)

Question 44

What are at the axon hillock the cause an action potential

Answer 44

Voltage gated Na+ channels

Question 45

Do dendrites have voltage gated Na+ channels

Answer 45

No

Question 46

What does myelin do to an axon

Answer 46

Makes the conduction of the AP faster because cells can't leak out

Question 47

Where are there a lot of unmyelinated axons

Answer 47

Cerebrum

Question 48

Which pain neuron is myelinated and unmyelinated

Answer 48

Myelinated: Sharp pain Unmyelinated: Dull pain

Question 49

How does MS prevent a neuron from conducting the impulse properly

Answer 49

The myelin on the neuron is lost and the AP diminshes because there are no voltage gated Na+ channels where the myelin was located.

Question 50

Card #50

Answer 50

Good luck on the test