Potentials

Question 1

Do all neurons and all cells have a resting membrane potential?

a) yes
b) only neurons
c) only other cells
d) neither

Answer 1

yes

Question 2

True or False: Neurons can rapidly change their resting membrane potential in a positive direction.

Answer 2

True

Question 3

Neurons are highly excitable like ________ cells

Answer 3

Voluntary Muscle

Question 4

What is required to keep opposite charges separated across a membrane?

Answer 4

Energy

Question 5

What happens when energy is liberated?

Answer 5

Charges move towards one another

Question 6

Do opposite charges attract?

Answer 6

Yes

Question 7

When does the system have potential energy?

Answer 7

When opposite charges are seperated

Question 8

What does it mean when a membrane is polarized?

Answer 8

Negative on the inside and positive on the outside

Question 9

What is voltage?

Answer 9

A measure of potential energy generate by separated charge

Question 10

How is voltage measured?

Answer 10

Between two points in volts (V) or millivolts (mV)

Question 11

Define potential difference or potential

Answer 11

The charge difference across the plasma membrane

Question 12

What results in a higher voltage?

Answer 12

Greater charge difference between points

Question 13

What is current?

Answer 13

The flow of electrical charge (ions) between two points

Can be used to do work

Question 14

What is the flow of current dependent on?

Answer 14

Voltage and resistance

Question 15

What is resistance?

Answer 15

It hinders current

Question 16

What is a substance with high electrical resistance called?

Answer 16

Insulator

Question 17

What is a substance with low electrical resistance called?

Answer 17

Conductor

Question 18

What are the two main types of ion channels?

Answer 18

Leakage (nongated)
Gated

Question 19

Which types of channels are always open?

Answer 19

Leakage (nongated)

Question 20

How do gated channels work?

Answer 20

Part of the protein changes shape to open/close the channel

Question 21

What are the three main gated channels?

Answer 21

Chemically gated
Voltage-gated
mechanically gated

Question 22

What is the role of membrane ion channels?

Answer 22

Large proteins (channels) that selectively let ions through the membrane

Question 23

What passes through k+ ion channels?

Answer 23

k+ ion

Question 24

Which channel will only open with the binding of a specific chemical? Name one chemical that might bind to it.

Answer 24

Chemically gated (ligand-gated)

Neurotransmitter

Question 25

Which channels open and close in response to changes in membrane potential?

Answer 25

Voltage-gated ion channels

Question 26

Which channels open and close in response to physical deformation of receptors such as sensory receptors?

Answer 26

Mechanically gated channels

Question 27

What is the electrochemical gradient

Answer 27

The combination of the electrical and chemical gradient ion flow create an electrical current + voltage changes across membrane

Question 28

What factors are important to cell voltage?

Answer 28

the difference in ion concentration inside and outside the cell + conductance (permeability) for that ion across the membrane *One cannot work without the other*

Question 29

What causes the resting membrane potential to change?

Answer 29

Change in [] of ions across membrane Change in membrane permeability to ions

Question 30

What types of signals do changes in membrane potential cause?

Answer 30

Graded potentials- Incoming signals over short distances Action potentials- Long distance signals of axons

Question 31

What is the purpose of changes in the membrane potential?

Answer 31

Used to create signals to receive, integrate, and send information

Question 32

What is depolarization?

Answer 32

decrease in membrane potential (moves toward zero and above) Inside of the membrane less negative then the resting membrane potential

Question 33

Does depolarization decrease the probability of impulses occurring?

Answer 33

No- It increases the probability of producing impulses

Question 34

What is hyperpolarization?

Answer 34

Increase in membrane potential (away from 0) Increase of membrane becomes more negative than resting membrane potential

Question 35

Does hyperpolarization increase or decrease the probability of producing impulses

Answer 35

decrease

Question 36

Describe Graded potentials in detail

Answer 36

Short-lived changes in membrane potential that are triggered by a stimulus that opens gated ion channels

Question 37

What are graded potentials names according to?

Answer 37

Location and function

Question 38

What are the types of graded potentials? What are there differences?

Answer 38

Receptor/generator potential- graded potentials in receptors of sensory neurons Postsynaptic potential- Neurons graded potential at a synapse

Question 39

True or false: In graded potentials, a stronger stimulus results in more voltage changes and farther current flows?

Answer 39

True

Question 40

True or false: In graded potentials, the current flows for a long time without decaying?

Answer 40

False- The current flows but dissipates quickly and decays because the current is lost through "leaky" plasma membrane and voltage is decremental

Question 41

What is the principal way that neurons send signals?

Answer 41

Action Potentials

Question 42

Where do action potentials occur?

Answer 42

Muscle cells and axons of neurons

Question 43

True or false: Action potentials decay over long distances?

Answer 43

False- Action potentials do not decay over long distances because it is constantly being regenerated graded potentials do

Question 44

What is another term for an action potential?

Answer 44

Nerve impulse

Question 45

How are action potentials generated?

Answer 45

Na+ influx causes depolarizations down the length of the axon

Question 46

Why does the action potential move in one direction down the axon?

Answer 46

Absolute refractory period

Question 47

What is the difference between the relative and absolute refractory period?

Answer 47

The relative refractory period can be overcome by a strong enough stimulus while the absolute refractory will not respond to any stimulus no matter how strong

Question 48

What is a refractory period? How does it occur?

Answer 48

The time in which a neuron cannot trigger another AP This occurs because the voltage-gated Na+ channels are open so the neuron cannot respond to another stimulus

Question 49

Which refractory period enforces one-way transmission of nerve impulses and ensures that each action potential is an all-or-none event?

Answer 49

Absolute

Question 50

What is happening during the absolute refractory period on a biological basis?

Answer 50

The time from the opening of Na+ channels until resetting of the channels

Question 51

What comes first, the absolute or relative refractory period?

Answer 51

Absolute, then refractory

Question 52

What is happening on a biological basis during the relative refractory period?

Answer 52

Most Na+ channels have returned to their resting state Some K+ channels are still open Repolarization is occurring

Question 53

How does the CNS tell the difference between a weak stimulus and a strong one?

Answer 53

Frequency of impulses- Aps received per second Higher frequency means stronger stimulus

Question 54

True or false: The intensity of the stimulus increases the strength of the action potential?

Answer 54

False- Only the frequency of APs has an effect on the strength of the action potential

Question 55

What are the subdivisions of postsynaptic potentials?

Answer 55

Excitatory (EPSP) Inhibitory (IPSP)

Question 56

What are the differences between excitatory postsynaptic potentials and inhibitory postsynaptic potentials?

Answer 56

EPSP- Trying to generate an AP by depolarizing the membrane and moving the membrane potential toward the threshold Opens channels that allow simultaneous fluxes in Na+ and K+ Moves toward 0 mV IPSP- Trying to move the membrane away from the threshold by hyperpolarizing Opens K+ or Cl- channels Moves toward - 90 mV

Question 57

What are the similarities between EPSPs and IPSPs?

Answer 57

Their gates are both opened by chemicals ex. neurotransmitters The refractory period is absent The summations are present; temporal or spatial Conduction distance is the same Voltage independent; Occurs when NT is no longer present