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CARDIO > Electrical properties > Flashcards

Electrical properties Flashcards

1
Q

Right side of heart pumps blood into

A

Pulmonary circulation

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2
Q

Left side of heart pumps blood into

A

Systemic circulation

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3
Q

What is atrial fibrillation

A

When atria do not contract correctly but ventricles can contract on their own

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4
Q

How before has the atria have to contract before the ventricle

A

1/6 of a second before

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5
Q

Do ventricles contract at the same time?

A

Yes

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6
Q

The cell membrane potential becomes more NEGATVIE when

A

Polarization

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7
Q

Cell membrane potential becomes more POSITIVE when

A

Depolarization

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8
Q

PHASE 0 corresponds to which ion

A

Fast Na+ influx

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9
Q

Why is there in PHASE 0 such a vertical increase in membrane potential (more positive)

A

Because of the rapid Na+ influx in the cell –> depolarized cell

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10
Q

What ion keeps the cell in a negative resting potential (inside)

A

K+

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11
Q

What returns membrane potential back to 0mV in PHASE 1

A

The slow opening of K+ channels so there is K+ efflux

+ ions outside of cell so -30mV –> 0 mV

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12
Q

Through what channel Ca++ ions INFLUX in PHASE 2

A

L-type Ca++ channels

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13
Q

Between what 2 ions is there an electrical balance during PHASE 2

A

Between Ca++ INFLUX and K+ EFFLUX

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14
Q

Through what channel do K+ ions EFFLUX in PHASE 2

A

Delayed rectifier K+ channels

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15
Q

What occurs in rapid REPOLARIZATION, rapid decrease of membrane potential mV? PHASE 3

A

The L-type Ca++ channels close but the K+ rectifier channels stay open so K+ ions flow outside of cell, making mV more negative

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16
Q

To what value does mV return to after rapid REPOLARIZATION

A

-90mV

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17
Q

What occurs in PHASE 4 during stable -90mV membrane potential

A

Both L-type Ca++ channels and Na+ channels closed

K+ rectifier channels opened to keep the membrane potential at -90mV

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18
Q

Why is there a plateau in action potential diagram

A

Due to an electric balance between Ca++ INFLUX and K+ EFFLUX

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19
Q

Why is the SA node different in generating an action potential

A

Because they have no resting potential

Generate regular, spontaneous AP

20
Q

EX. Of muscle undergoing these PHASES

A

Ventricular action potential

21
Q

Which phases are missing in pacemaker action potential

A

Phases 1 and 2 because there is no plateau

22
Q

In PHASE 4 PAP what causes depolarization before -50mV

A

The funny Na+ currents. Na+ INFLUX into cell that causes SPONTANEOUS depolarization

23
Q

What starts PHASE 4 PAP

A

Funny Na+ currents

24
Q

What occurs at -50mV and -40mV in PAP

A
  • 50mV the T-Type Ca++ channels open that contribute to depolarization along with Funny Na+ currents
  • 40mV the threshold is crossed and L-type Ca++ channels open that cause great depolarization
25
Q

What closes when L-type Ca++ channels open

A

Funny Na+ currents and T-type Ca++ channels

26
Q

PHASE 3 PAP

A

K+ channels open causing HYPERPOLARIZATION so L-type Ca++ channels close (stopping depolarization)

27
Q

What is refractory period

A

Time between phase 0 and next possible depolarization

28
Q

0.15 sec is atrial or ventricular refractory period

29
Q

0.25-0.3 is atrial or ventricular refractory period

A

Ventricular

30
Q

Which refractory period is longer, atrial or ventricular

A

Ventricular refractory period

31
Q

Is troponin C only present in cardiac muscle cells

32
Q

Why does cardiac automatism occur in nodes

A

Because phase 4 is unstable so cells tend to automatically depolarize

33
Q

What allows for shorter refractory period in the pacemaker action potential

A

Because it lacks phase 1 and 2 so there is no plateau, faster depolarization

34
Q

80bmp of

35
Q

40-60 bpm

36
Q

15-40 bpm

A

Purkinje system

37
Q

What is an ectopic pacemaker

A

Pacemaker not on SA node / atria / ventricle

38
Q

Why is AV node block dangerous

A

Because there are 2 different heart rates so atria contracts faster than ventricle

39
Q

Which is the most common arrythmia

A

Atrial fibrillation

40
Q

Why does ventricular fibrillation lead to cardiac arrest

A

Because there is not enough blood pumped to systemic circulation

41
Q

Why are we able to slow down heart rate

A

Bc AV node is NOT AN ELECTRICAL TISSUE –> electricity cannot go back to atria

42
Q

Sympathetic chain connects heart to

A

Sympathetic chain

42
Q

Parasympathetic system connects heart to

A

Vagus nerve

42
Q

What will never have a denervated (transplanted heart)

A

Parasympathetic / sympathetic innervation

43
Q

Parasympathetic system inhibits

A

Na+ and Ca+ entry to cell –> causing depolarization

44
Q

Under which system is the resting potential more negative

A

Parasympathetic nervous system

45
Q

Refractory period is shorter under which nervous system

A

Sympathetic

CARDIO (8 decks)

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