Chapter 4

Question 0

resting potential

Answer 0

membrane potential of cells at rest (RMP)

- -70 mV

Question 1

membrane potential

Answer 1

separation of positive and negative charges across a membrane

Question 2

polarization

Answer 2

when the membrane potential is other than 0 mV

Question 3

depolarization

Answer 3

membrane potential moves closer to 0 mV from RMP

Question 4

repolarization

Answer 4

membrane returns to resting potential after depolarization

Question 5

hyperpolarization

Answer 5

membrane becomes more polarized than at resting potential

Question 6

electrical signals are produced by changes in _____

Answer 6

ion movement

Question 7

positive charges flow in –> _______

Answer 7

depolarization

Question 8

positive charges flow out –> _________

Answer 8

repolarization

Question 9

ion movement results from changes in ________ of cell membrane to ions

Answer 9

permeability

Question 10

leak channels

Answer 10

open all the time - unregulated diffusion

Question 11

gated channels

Answer 11

can open and close

Question 12

voltage gated channels

Answer 12

respond to changes in mp

Question 13

chemical gated channels

Answer 13

respond to chemical messengers

Question 14

mechanical gated channels

Answer 14

respond to stretch

Question 15

graded potentials

Answer 15

serve as short-distance signals

• occurs in small, specialized region of excitable cell membranes
• magnitude of GP varies directly with the magnitude of the triggering event
• decremental spread - signal gradually decreases
• if big enough, GP can initiate AP

Question 16

Action potentials

Answer 16

serve as long-distance signals

• brief, rapid, large changes in membrane potential during which inside becomes more (+) than outside
• non-decremental conduction - signal arrives at full speed
• threshold potential mp to which membrane must be depolarized to initiate action potential

Question 17

GP example

Answer 17

ripple effect

Question 18

if threshold potential is not met, an AP will _____ occur. Threshold is the _________ point

Answer 18

not

all or none

Question 19

in neuron, threshold potential is ______ mV

Answer 19

-50 to -55

Question 20

AP in detail:
Triggering event = _____ from resting potential to _____ potential then rapid depolarization then rapid _______ with a brief _______ and return to resting potential

Answer 20

depolarization
threshold
repolarizatoin
hyperpolarization

Question 21

Na+ channels

Answer 21

2 gates

1. activation - hinge door
2. inactivation - ball and chain

Question 22

K+ channels

Answer 22

1 gate:

either open or closed (hinge)

Question 23

ion movement during AP

Answer 23

1. Na+ gates open = depol (Na+ is rushing in) - open at -55 mV
2. Na+ gates close (close by +30mV)
3. K+ gates open = repol (K+ is rushing out - open at +30mV)
4. resting potential is restored
5. Na+/K+ pump restores ion concentration gradient

Question 24

sodium is pumped ____ and potassium is pumped ____

Answer 24

out | in

Question 25

refractory period

Answer 25

ensures one way propagation of AP ( a new AP cannot be generated)

Question 26

Absolute Refractory Period

Answer 26

unresponsive to further stimulate | - Na+ gate are not in resting conformation - ball and chain plugged the opening

Question 27

Relative Refractory Period

Answer 27

AP only if triggering event is STRONGER than usual - makes sure AP only occur in one direction - period of K+ outflux and hyperpolarization (-80mV)

Question 28

membrane potential

Answer 28

separation of + and - charges across a membrane

Question 29

resting potential

Answer 29

membrane potential of cells at rest (RMP) | -70 mV

Question 30

depolarization

Answer 30

membrane potential moves closer to 0 mV from RMP

Question 31

repolarization

Answer 31

membrane returns to resting potential after depolarization

Question 32

hyperpolarization

Answer 32

membrane becomes more polarized than at resting potential

Question 33

is hyperpolarization an upward or downward from RMP

Answer 33

downward

Question 34

now if diffusion is going to take place, which way will these ions move?

Answer 34

K+ wants to go out, Na+ wants to move in

Question 35

voltage gated

Answer 35

respond to changes in membrane potential

Question 36

chemically gated

Answer 36

respond to chemical messengers