Ch 5 Membrane Potential and Action Potential Flashcards Preview

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Flashcards in Ch 5 Membrane Potential and Action Potential Deck (28):
1

after-hyperpolarization

membrane potential following an action potential.

2

Which ions are actively concentrated within and which extruded to generate membrane potential?

K+: in. Na+, Cl-, and Ca2+: out

3

reversal potential

the membrane potential at which the net current flips

4

membrane potential

difference in electrical potential between the interior and exterior of cells

5

grand mal/tonic-clonic seizure

large numbers of neurons on the cerebral cortex dump K+

6

Na+ -K+ pump

moves Na+ out of the cell while moving -K+ in through hydrolysis

7

equilibrium potential

K+ ions flowing out due to concentration gradient is offset by K+ ions entering due to negative potential inside the cell

8

How many Na to K are transferred in the pump?

3 Na for 2 K

9

Na+ Ca2+ exchanger

keeps Ca low inside the cell by exchanging 1 for 1

10

3 properties that influence passive charge response

membrane resistance, axial resistance, membrane capacitance

11

capacitance

the ability to store electrical charge

12

axial resistance

resistance in the movement of axial current due to properties of organelles and cytoplasm

13

length constant

the point at which membrane potential drops to 37%

14

TTX

Tetradotoxin, poison found in the pufferfish that blocks voltage dependent Na+ currents

15

differences in Na and K action potentials

K+ current activates slowly. Na+ activates and deactivates rapidly.

16

mutagenesis

genetic material is changed in a stable manner

17

Graded Potential, 3 things...

1)Depolarization or hyperpolarization
2)Travel short distances
3) Lose strength as travel through cell

18

Action potential, 3 things...

1) Large uniform depolarizations
2) Travel rapidly without losing strength
3) Travel long distances

19

Where do graded potentials begin?

Dendrites or cell body at point of ion entry

20

In a graded potential what determines amplitude size. hyperpolarization?

More Na+ channels open, higher amplitude. K+ open, hyperpolarization.

21

Trigger Zone

Where the action potential occurs, where there are a lot of sodium channels.

22

Where are the trigger zones?

MOTOR neurons: axon hillock. SENSORY neurons, the 1st unmyelinated area (first node of ranvier).

23

What do axon potentials result from?

Changes in membrane permeability to Na+ and K+

24

3 phases of an action potential

1. rising (Na+ open) 2. falling (K+ channels open) 3. hyperpolarization (due to excess K+)

25

Na channel gates, resting vs. depolarized

Resting: Activation gate closed/inactivation gate open.
Depolarized: opens activation gate and opens channel

26

Which ions are usually high inside and low outside?

Potassium and Phosphates

27

Which ions are usually low inside and high outside?

Sodium and Chloride

28

Which 3 ions generally determine membrane potential?

Na+, K+, Cl-