Neuro psych Quiz 1.2

Question 1

electrical gradient/polarization

Answer 1

The difference in electrical charge between the inside and outside of the cell during rest.

Question 2

resting potential

Answer 2

the difference between the negative electrical potential inside the membrane vs the more positive electrical potential outside the membrane

Question 3

selectively permeable

Answer 3

some chemicals pass through the membrane more freely than others.

Question 4

at rest, are the sodium and potassium channels closed or open>

Answer 4

closed. this allows for almost no flow of sodium and a small flow of potassium

Question 5

Sodium-potassium pump

Answer 5

A protein complex that transports 3 sodium ions out of the cell and two potassium ions into it.

Question 6

concentration gradient

Answer 6

the difference in distribution of ions across the membrane.

Question 7

Is sodium positively or negatively charged?

Answer 7

Positively

Question 8

When the membrane is at rest, what tends to drive the potassium ions out of the cell

Answer 8

the concentration gradient

Question 9

When the membrane is at rest, what tends to draw the potassium ions into the cell

Answer 9

Electrical gradient/sodium-potassium pump

Question 10

action potentials

Answer 10

messages sent by axons

Question 11

hyperpolarization

Answer 11

increased polarization or to further increase the negative charge inside the neuron

Question 12

depolarization

Answer 12

to reduce polarization toward zero

Question 13

what happens when one stimulates beyond the threshold of excitation

Answer 13

a massive depolarization of the membrane

Question 14

What happens when the stimulus reaches the threshold?

Answer 14

the sodium channel is opened

Question 15

What is the relationship between the threshold and an action potential

Answer 15

A depolarization that passes the threshold produces an action potential. One that falls short of the threshold does not produce an action potential.

Question 16

threshold of excitation

Answer 16

produces a massive depolarization of the membrane.

Question 17

What is the difference between hyperpolarization and depolarization?

Answer 17

Hyperpolarization is an exaggeration of the normal negative energy. Depolarization is a movement towards zero

Question 18

What is the relationship between the threshold and an action potential?

Answer 18

When the threshold is reached an action potential starts. If not, no action potential

Question 19

voltage-gated channels

Answer 19

regulate sodium and potassium. the permeability depends on the voltage difference across the membrane.

Question 20

Local anesthetic drugs

Answer 20

attach to sodium channels of the membrane, preventing sodium ions from entering, stopping action potentials (Novocain and Xylocaine)

Question 21

During the rise of the action potential, do sodium ions move into the cell or out of it?

Answer 21

they move in because the concentration and electrical gradient pull sodium in.

Question 22

As the membrane reaches the peak of the action potential, what brings the membrane down to the original resting potential?

Answer 22

The exiting of potassium from the membrane.

Question 23

All or none law

Answer 23

the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it, provided that the stimulus reaches the threshold.

Question 24

Refractory period

Answer 24

immediately after an action potential when the cell resists the production of further action potentials

Question 25

Absolute refractory period

Answer 25

when the membrane cannot produce and action potential, regardless of the stimulation

Question 26

Relative refractory period

Answer 26

when a stronger than usual stimulus is necessary to initiate an action potential

Question 27

propagation of the action potential

Answer 27

describes the transmission of an action potential down an axon.

Question 28

What does saltatory conduction come from?

Answer 28

The Latin word soltare meaning to jump

Question 29

saltatory conduction

Answer 29

the jumping of action potentials from note to node

Question 30

why is an unmyelinated axon so different from one that lost its myelin sheath?

Answer 30

Because it does not have sodium channels where the myelin used to be.

Question 31

local neurons

Answer 31

do not have axons, do not follow all or none law, has a graded potential

Question 32

graded potential

Answer 32

A membrane potential that varies in magnitude in proportion to the intensity of the stimulus

Question 33

When the membrane is at rest, where is sodium more concentrated and were is potassium more concentrated?

Answer 33

Sodium is more concentrated outside and potassium more concentrated inside.

Question 34

When at rest, the concentration gradient pulls potassium where and the electrical gradient pulls potassium where?

Answer 34

The concentration gradient pull potassium out of the neuron and the electrical gradient pulls potassium ions into the neuron

Question 35

When at rest, the concentration gradient pulls sodium where and the electrical gradient pulls sodium where?

Answer 35

Both pull sodium in

Question 36

Sodium-potassium pump pulls sodium where and potassium where?

Answer 36

It pulls sodium (3) out and potassium (2) in

Question 37

If the neuron goes from -70mV to -80mV what is it called?

Answer 37

Hyperpolarization

Question 38

Under what condition does an axon produce an action potential?

Answer 38

Whenever the membrane's potential reaches the threshold

Question 39

During the rising portion of the action potential, which ions are moving across the membrane and in which direction?

Answer 39

Sodium ions and the move in

Question 40

After the action potential reaches its peak, the potential across the membrane falls toward its resting level. Why?

Answer 40

Potassium ions move out because their channels are open and the electrical gradient pushes them out

Question 41

What is one way of stating the all or none law

Answer 41

All stimuli that exceed the threshold produce equivalent responses in the axon

Question 42

What does the myelin sheath of an axon accomplish?

Answer 42

It insulates and enables action potentials to travel more rapidly.

Question 43

Is it true we only use 10% of our brain?

Answer 43

No,