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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
What closes when L-type Ca++ channels open
Funny Na+ currents and T-type Ca++ channels
26
PHASE 3 PAP
K+ channels open causing HYPERPOLARIZATION so L-type Ca++ channels close (stopping depolarization)
27
What is refractory period
Time between phase 0 and next possible depolarization
28
0.15 sec is atrial or ventricular refractory period
Atrial
29
0.25-0.3 is atrial or ventricular refractory period
Ventricular
30
Which refractory period is longer, atrial or ventricular
Ventricular refractory period
31
Is troponin C only present in cardiac muscle cells
Yes
32
Why does cardiac automatism occur in nodes
Because phase 4 is unstable so cells tend to automatically depolarize
33
What allows for shorter refractory period in the pacemaker action potential
Because it lacks phase 1 and 2 so there is no plateau, faster depolarization
34
80bmp of
SA
35
40-60 bpm
AV
36
15-40 bpm
Purkinje system
37
What is an ectopic pacemaker
Pacemaker not on SA node / atria / ventricle
38
Why is AV node block dangerous
Because there are 2 different heart rates so atria contracts faster than ventricle
39
Which is the most common arrythmia
Atrial fibrillation
40
Why does ventricular fibrillation lead to cardiac arrest
Because there is not enough blood pumped to systemic circulation
41
Why are we able to slow down heart rate
Bc AV node is NOT AN ELECTRICAL TISSUE --> electricity cannot go back to atria
42
Sympathetic chain connects heart to
Sympathetic chain
42
Parasympathetic system connects heart to
Vagus nerve
42
What will never have a denervated (transplanted heart)
Parasympathetic / sympathetic innervation
43
Parasympathetic system inhibits
Na+ and Ca+ entry to cell --> causing depolarization
44
Under which system is the resting potential more negative
Parasympathetic nervous system
45
Refractory period is shorter under which nervous system
Sympathetic

CARDIO (8 decks)

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