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anatomy > Membrane Potentials > Flashcards

Membrane Potentials Flashcards

1
Q

Greater charge separation results in what?

A

greater # of volts

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2
Q

What is potential difference?

A

Separation of electrical charges across inside and outside of plasma membraneT

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3
Q

There are charged ____ and _____ inside the membarne

A

particles and proteins

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4
Q

Sodium tries to ____ cell, which is termed ___-

A

enter, influex

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5
Q

Why dose sodium want to enter the cell?

A

it wants to go down its concentration and charge gradient

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6
Q

When Na enters the cell, what happens to the potential difference?

A

potential difference is lessened, i.e. voltage moves towards 0

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7
Q

Sodium entering the cell causes ________

A

depolarization

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8
Q

Potassium ions try to ______ cell, this is called

A

leave, efflux

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9
Q

When K leaves the cell, what happens to the potential difference?

A

potential difference is greater, voltage becomes more - becomes + is leaving, therefore further from 0

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10
Q

Potassium leaving the cell causes

A

hyperpolarization

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11
Q

What are neurons RMP?

A

-70

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12
Q

What are the two forces acting on ions contributing to RMP?

A

charge gradient and concentration gradien

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13
Q

What are the two things that cause RMP?

A

membrane is differentially permeapse and the sodium-potassium ATPase

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14
Q

Explain what “membrane is differentially permeable” means

A

membrane is less permeable to Na than K, therefore sodium leaks slower than K, causes a net negative charge in cell

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15
Q

Explain the sodium-potasium ATPase pump

A

due to leakyness ions have to be returned to OG location

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16
Q

How many Na pumped out for every k pumped in?

A

2 sodium ions pumped out for every 2K pumped in

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17
Q

Pump can be described as

A

electrogenic

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18
Q

Describe pump mechanism

A

ATP binds to receptor, convertsit to ADP&Pi, pump becoems activated with energy, 3Na out and 2k in, ADP and Pi leave

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19
Q

ATP pushes _______ _______ and address _____

A

against gradient and addresses leakage

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20
Q

Which cells are excitable?

A

muscles and nerve cells

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21
Q

What are MPs used for?

A

to send electrical signals for communication

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22
Q

What are the two types of membrane potential changes?

A

action and graded potential

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23
Q

What are two ways of changing potential?

A

voltage gates or ligand gated ion channels

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24
Q

Cations in , potential difference ____, cell is _____

A

lessens, cell is depolarized

25
Q

cations out, potential difference ____, cell is

A

increases, cell is hyperpolarized

26
Q

Graded potentials are ______ to _______ ______

A

graded potentials are precursors to action potentials

27
Q

Graded potentials are ______ _____-

A

short lived

28
Q

Difference between AP and GP?

A

Graded potentials are local (donts spread v far), GP can be summated

29
Q

What type of ion channels are GP

A

ligand gated ion channels

30
Q

What brings GP back to RMP?

A

negative feedback mechanism

31
Q

What is spatial summation?

A

GP occurring near each other

32
Q

What is temporal summation?

A

GP occurring close enough together in time

33
Q

Graded potentials are added up if they occur w/in few ____ & ____

A

ms & mm

34
Q

Action potentials work via _____ feedback mechanism

A

positive

35
Q

Explain the positive feedback mechanism

A

increase in voltage triggers more increase

36
Q

Voltage gated sodium channels open when?

A

once membrane potential reaches threshold

37
Q

What are the five phases of AP?

A

resting phase, depolarizing phase, repolarizing phase, hyperpolarizing phase, resting phase

38
Q

What happens in the resting phase

A

all channels are closed

39
Q

What happens in the depolarizing phase?

A

Stimulation causes voltage to rise, ligand gated sodium channels open, threshold is reached and triggers voltage gated sodium channels to open

40
Q

What happens in the repolarizing phase?

A

voltage gated K channels open and sodium channels begin closing

41
Q

What happens in hyperpolarizing phase?

A

sodium channels are fully closed, voltage gated K channels are open

42
Q

which phases are sodium channels open?

A

depolarizing and repolarizing

43
Q

When cant you fire an AP?

A

once an AP has started, once K is rushing out

44
Q

Define absolute refractory period

A

start of NA threshold to end of repolarizing

45
Q

Define the term relative refractory period

A

can send a message but need strong stimulus

46
Q

Why is it called RELATIVE refractory period?

A

bc cell is hyperpolarized and therefore more negative, making it hard to stimulate an AP and need ever more channels to reach a threshold

47
Q

At what voltage do voltage sensitive sodium channels open?

A

-50

48
Q

Describe the negative feedback mechanism of AP

A

occurs at end to restore potential by opening voltage gated K+ channels and close Na channels

49
Q

What instrument measures electrical activity in muscles?

A

electromyography

50
Q

What does electromyography do?

A

EMG measures electrical activity in muscles

51
Q

Define conduction velocity

A

can be calculated by knowing when nerve is stimulated and when uscle contracts and the physical distance btw them

52
Q

How do EMGs work?

A

stimulate nerve using electrical stiulator and observe contraction

53
Q

Why is incandescent light 60Hz?

A

so light doesnt appear to flicker

54
Q

What is tetany

A

muscle cramp

55
Q

What is the AC frequency in canada?

A

110V of AC with frequency of 60Hz

56
Q

Which muscle is affected in tetany?

A

skeletal muscles

57
Q

What causes tetany

A

stimulation of currents with frequency 40-110 Hz

58
Q

What is death grip and why does it occur?

A

can’t let go bc flexors are strong than extensors and there isnt enough time to let go

59
Q

What does DC do to muscles?

A

produce a single, large muscle contraction that throws electrocuted person away from source

anatomy (12 decks)

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