Chapter 3: Neurophysiology

Question 1

Two ways neurons communicate with each other

Answer 1

Electrical and chemical communication

Question 2

Nerve impulse

Answer 2

Neurons receive, integrate, and send electrochemical signals

Question 3

When salts go into solution, they break apart into ____

Answer 3

Ions

Question 4

Is there more or less of potassium inside a cell?

Answer 4

More

Question 5

Is there more or less of potassium outside a cell?

Answer 5

Less

Question 6

Is there more or less of Sodium inside cell?

Answer 6

Less

Question 7

Is there more or less of sodium outside of a cell?

Answer 7

More

Question 8

Inside of cell is more (negative/positive) than outside

Answer 8

Negative

Question 9

Outside of cell is more (negative/positive) than outside

Answer 9

Positive

Question 10

Resting potential of a neuron

Answer 10

-70 mv

Question 11

What does -70 mv resting potential mean?

Answer 11

Inside of cell is 70 mv less than outside of cell

Question 12

Ions mostly move through _____

Answer 12

Channels

Question 13

Protein channels are ______ for one type of ion

Answer 13

Specific

Question 14

Ion channels are normally closed or ____

Answer 14

gated

Question 15

The two forces that act to drive ion movement

Answer 15

Concentration gradient and electrical gradient

Question 16

Concentration gradient

Answer 16

Ions in high concentrations move where it is less concentrated

Question 17

What is the movement of Na+ due to concentration gradient?

Answer 17

From outside to inside

Question 18

What is the movement of K+ due to concentration gradient?

Answer 18

Inside to outside

Question 19

Electrical Gradient

Answer 19

Similar charges repel each other and opposites attract

Question 20

Movement of Na+ because of electrical gradient

Answer 20

It is driven inside where it is more negative

Question 21

Electrochemical gradient

Answer 21

Both electrical and concentration gradients

Question 22

Where do action potentials begin?

Answer 22

Axon hillock

Question 23

From where to where do axons send information?

Answer 23

From cell body to axon terminal

Question 24

Depolarization

Answer 24

If you add positive current to inside of cell and polarity moves toward 0; more positive

Question 25

Hyperpolarization

Answer 25

If you add negative current to inside of cell; polarity moves away from resting potential; more negative

Question 26

Threshold of excitation

Answer 26

-55 mV

Question 27

What happens when neuron reaches threshold of excitation?

Answer 27

When voltage gated Na+ channels open and enough positive current flow into to trigger an action potential

Question 28

All-or-none

Answer 28

Either generate action potential or you don't (no in-between)

Question 29

At resting potential, the voltage gated Na+ channels are _____

Answer 29

Closed

Question 30

What happens to voltage gated Na+ channels when the membrane is depolarized?

Answer 30

Conformation changes open the voltage gated channel

Question 31

What happens after voltage gated Na+ channels open?

Answer 31

Na+ enters cell through channels and inside becomes more positive or depolarized

Question 32

When cell reaches positive +50 mV, what happens to the Na+ and K+ channels?

Answer 32

Na+ channels inactivate or close. K+ channels open

Question 33

When K+ voltage gated channels are opened, what happens to K+ and inside of cell?

Answer 33

It exits cell and inside becomes more negative

Question 34

After-hyperpolarization

Answer 34

K+ channels slow to close; more K+ leaks out

Question 35

Na+/K+ Pump | What is the exchange and does it require energy?

Answer 35

- Helps to restore balance of Na+ and K+ - Moves 3 Na+ ions outside and 2 K+ ions outside - It requires ATP

Question 36

Absolute refractory period

Answer 36

- Impossible to generate another AP | - When inside of cell is above threshold of excitation

Question 37

Relative refractory period

Answer 37

- Can generate another AP, but harder - During the after-hyperpolarization - Need much more positive current to bring membrane to threshold (-55mV)

Question 38

The three phases of an action potential

Answer 38

Depolarization, Repolarization, Hyperpolarization

Question 39

What phase(s) of the AP constitute the absolute refractory period?

Answer 39

Depolarization and repolarization

Question 40

What phase(s) of the AP constitute the absolute refractory period?

Answer 40

Hyperpolarization

Question 41

Toxins and what they affect

Answer 41

They are noxious or poisonous substances. They have effects on action potential.

Question 42

Tetrodotoxin and saxitoxin

Answer 42

Block voltage gated Na+ channels

Question 43

Scorpion venom

Answer 43

Keeps voltage-gated Na+ channels open; closes voltage gated K+ channels

Question 44

2 examples of local anesthetics

Answer 44

Lidocaine and novocaine

Question 45

Local anesthetics

Answer 45

Block voltage gated Na+ channels in a localized area

Question 46

To propagate

Answer 46

To generate/give rise to

Question 47

Is action potential re-generated along axon?

Answer 47

Yes

Question 48

What is pattern of action potential along a myelinated axon?

Answer 48

It appears to skip along the axon

Question 49

Nodes of ranvier

Answer 49

- Spaces between sections of myelin | - High concentrations of ion channels

Question 50

Myelin

Answer 50

Good insulator

Question 51

Multiple sclerosis

Answer 51

- Autoimmune disease - Lose insulation, ions leak out - Propagation affected; muscle slowness, weakness

Question 52

Non-decremental

Answer 52

- regenerate along the axon | - Size and shape same every time

Question 53

Neurons receive

Answer 53

Graded potentials

Question 54

Neurons integrate

Answer 54

What happens at axon hillock (does the membrane each threshold of excitation?)

Question 55

Neurons send

Answer 55

action potential and release of chemicals

Question 56

Graded potentials

Answer 56

Small membrane potentials that can be excitatory or inhibitory

Question 57

Grade potentials' size is proportional to

Answer 57

size of stimulus that generates them

Question 58

Are graded potentials persistent over time?

Answer 58

No, they decay over time and space. They are non-regenerative

Question 59

EPSP occur due to ____ or ____ influx

Answer 59

Na+ or Ca++

Question 60

EPSPs are each ____ for generating action potential

Answer 60

sub threshold

Question 61

IPSPs usually result from ___ or ___

Answer 61

Cl- influx or K+ efflux

Question 62

How do EPSPs and IPSPs add together?

Answer 62

The ions diffuse inside cell and their concentration decays with space and time. They summate at axon hillock.

Question 63

Neuronal decision-maker

Answer 63

Axon hillock; decides if enough to reach threshold of excitation and if so, it generates an action potential

Question 64

Neurons that receive signals receive them from other neurons that send them

Answer 64

True; concept check