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Block 5 ellen > Action potential L8 > Flashcards

Action potential L8 Flashcards

1
Q

action potential=

A

rapid change in electrical potential across the plasma membrane of a cell.

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2
Q

Cells that generate action potentials (3)

A 
neurons (nerve cells)
Muscle fibres (muscle cells)
Endocrine cells
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3
Q

Action potential in neurons

A

initiates cell to cell communication

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4
Q

action potential in muscle

A

initiates steps leading to muscle contraction

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5
Q

Action potential in endocrine

A

initiates hormone release

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6
Q

Graded response=

A

the response is proportional to the amount of excitation it receives.

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7
Q

What is the space between cell body and axon called

A

axon hillock

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8
Q

Where does an action potential first arrive

A

dendrites

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9
Q

How do action potentials pass from the dendrites to soma

A

passively (graded response)

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10
Q

What happens to negative and positive electronic potentials in the soma

A

they are integrated (summed)

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11
Q

Sum of action potentials reaches the _____

A

axon hillock

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12
Q

What response ensues at the axon hillock

A

all or nothing action potential

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13
Q

What need to happen for an action potential at the hillock;

A

net electric potential> threshold

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14
Q

What is a non-decremental spread

A

all or non response

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15
Q

membrane potential=

A

the difference in electrical potential between inferior and exterior of a cell.

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16
Q

What is a membrane potential measured in

A

volts or millivolts

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17
Q

Stages of an action potential

A 
stimulus 
depolarisation 
action potential 
repolarisation 
refractory period
resting state
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18
Q

What is the normal resting membrane potential

A

-70 mv

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19
Q

The charge of the inside of a neuron is

A

negative

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20
Q

The charge of the outside of a neuron=

A

positive

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21
Q

main ions involved in neurons action potential

A

sodium (Na+)

potassium (K+)

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22
Q

The extracellular fluid contains lots (2)

A

sodium ions and chloride

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23
Q

The inside of the cell contains (3)

A

negative proteins
phosphate ions
potassium ions

24
Q

leak ion channels are

A

always open, continually leak specific ions across membrane

25
Q

voltage-gated ion channels=

A

open or close in response to voltage change

26
Q

ligand gated ion channels=

A

open or close in response to chemical or drug

27
Q

Na+/ K+ pump is powered by

A

active transport (needs ATP)

28
Q

Na+/K+ ratio

A

pumps 3 Na+ out for every 2 K+ in

29
Q

Three main factors that set up the resting membrane potential

A
  1. low protein permeability ( negative proteins can’t leave)
  2. Na+/K+ pump
  3. High K+ permeability (moves freely through leak channels)
30
Q

More Na+ is

A

extracellular

31
Q

Equilibrium potential=

A

voltage at which ion’s net flow across membrane is 0

32
Q

Equation that can predict a single ions equilibrium potential

A

nernst equation

33
Q

equilibrium potential for K+

A

-80mV

34
Q

Equilibrium potential for Na+

A

+61mV

35
Q

2 main things nernst equation considers

A

valence (charge)

Concentration gradient

36
Q

What equation can measure the resting membrane potential

A

goldmans equation

37
Q

Why is the resting membrane potential close to equilibrium potential of K

A

Because neurons are highly permeable to K+

38
Q

explain resting state of AP

A

-70mV
all voltage-gated Na+ and K+ channels closed
Only leak channels open

39
Q

Explain depolarisation (AP)

A 
-55mV
voltage sensitive (fast activation) gates of Na+ channels open----> sodium rushes into cells making it more positive
40
Q

What is threshold potential

A

-55mV

41
Q

explain repolarisation (AP)

A

+40mV

Voltage sensitive K+ channels open—> potassium rushes out of cell making the inside of the cell more negative again

42
Q

Explain after hyperpolarisation

A

-80mV

voltage sensitive K+ channels stay open and Na+ fast activation gates close

43
Q

below threshold what determines the action potential

A

magnitude of graded response

44
Q

Above threshold what determines the response

A

Frequency of action potentials (strong stimulus–> rapidly fire)

45
Q

What ensues one-way propagation of the action potential

A

refractory period (previous Na+ channels are inactivated)

46
Q

What happens on a myelinated axon

A

saltatory conduction

47
Q

2 things axon conduction velocity depends on

A

axon diameter

myelination

48
Q

unmyelinated axons are better for

A

smaller axons

49
Q

Myelinated axons are needed for

A

larger diameter axons

50
Q

In myelinated axons velocity ;

A

linear with diameter

51
Q

(3) myelinated axons

A

A alpha
A beta
A delta

52
Q

unmyelinated axon=

A

C fibres

53
Q

What does Tetrodotoxin do

A

Na+ channels blocker

54
Q

What is multiple sclerosis

A

T-cells attack myelin sheaths causing inflammation

55
Q

What does local anaesthetic do

A

reversibly block voltage-gated sodium channels

Block 5 ellen (17 decks)

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