Chapter 1.a Concept Review: Action Potential - Myocardial Cell Flashcards

1
Q

how many phases is action potential of myocardial cell divided into?

A

5; phases 0, 1, 2, 3, 4

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2
Q

phase 0 represents

A

ventricular depolarization

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3
Q

rapid depolarization depends on initial entry of which electrolyte?

A

Na+

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4
Q

resting potential of myocardial cell

A

-90 mV

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5
Q

positive potential of myocardial cell

A

20 mV

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6
Q

what is phase 0, ventricular depolarization, represented as on the ECG?

A

QRS wave

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7
Q

ventricular repolarization occurs during which phases?

A

phases 1, 2, and 3

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8
Q

which electrolyte channel is closed (and inactivated), and which electrolyte channel is opened during phase 1?

A
  • Na+

- K+

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9
Q

during phase 2, neutral potential is maintained by balancing which electrolytes?

A
  • efflux of K+

- ENTRY of Ca++

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10
Q

phase 2 is AKA

A

plateau phase

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11
Q

what is phase 1 represented as on the ECG?

A

J point

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12
Q

what is phase 2 represented as on the ECG?

A

ST segment

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13
Q

what does phase 3 represent?

A

rapid repolarization to negative resting potential

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14
Q

which electrolytes are opened and closed during phase 3, rapid repolarization?

A
  • continued efflux of K+

- CLOSURE of Ca++

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15
Q

what is phase 3 represented as on the ECG?

A

T wave

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16
Q

how is the resting membrane potential maintained during phase 4?

A
  • continued efflux of K+

- Na+/K+ ATPase pump

17
Q

when is the ventricular myocardium in its resting potential (phase 4) on the ECG?

A

between end of T wave and beginning of next QRS wave (T-Q segment)