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CVRH Exam 2 > Electrical Properties of the Heart I > Flashcards

Electrical Properties of the Heart I Flashcards

1
Q

What occurs in phase zero?

A

Rapid depolarization

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2
Q

What occurs in phase one?

A

Rapid but incomplete repolarization (not SA/AV)

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3
Q

What occurs in phase two?

A

Plateau

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4
Q

What occurs in phase three?

A

Slow, delayed repolarization

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5
Q

What occurs in phase four?

A

Slow, diastolic depolarization (not atrial/ventricular myocardium)

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6
Q

What effect on action potential does hypokalemia have?

A

Prolongs action potential

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7
Q

What channels are active in phase 0?

A

Sodium current

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8
Q

What channels are active in phase 1?

A

Ikto- transient inward current potassium

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9
Q

What channels are active in phase 2?

A

Ica-t: transient

Ica-l: long

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10
Q

What channels are active in phase 3?

A

Ikur: terminates phase 2
Ikr: sustains depolarization
Iks: sustains depolarization

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11
Q

What channels are active in phase 4?

A

NCX

Voltage dependent IK1

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12
Q

What is a relative refractory period?

A

Time when the cell is still repolarizing but is still able to send an action potential with enough stimulus

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13
Q

What is effectively refractory period defined as?

A

2x the threshold current

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14
Q

What tract runs anterior?

A

Bachman’s bundle

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15
Q

What tract runs posterior?

A

Thorel’s tract

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16
Q

What tract runs middle?

A

Wenckebach’s tract

17
Q

What agents close gap junctions or cause uncoupling?

A

Acidosis/ischemia
ATP depletion/ischemia
Increased intracellular calcium/injury

18
Q

Where are connexons found in normal heart cells?

A

End to end

19
Q

Where are connexons found in fibrosis?

A

Side to side

20
Q

What PSNS nerve innervates the heart?

A

Vagus nerve

21
Q

What does the right vagus nerve innervate?

A

SA node

22
Q

What does the left vagus nerve innervate?

A

AV node

23
Q

What is If funny current?

A

Pacemaker channel present in SA and AV nodes; determinant of automaticity

24
Q

What regulates the current of If funny channels?

A

cAMP increased levels increases current

25
Q

What are the effects of acetylcholine?

A

Decreased cAMP and If (diastolic depolarization)
Increased IkACH (hyperpolarization)
Decreased Ica-L SR Ca2+ release decreased NCX

26
Q

What affect does an increase in IkACH channels cause?

A

Decreased pacemaker activity

CVRH Exam 2 (25 decks)

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