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

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Flashcards in Chapter 1.a Concept Review: Action Potential - Myocardial Cell Deck (17)
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1

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

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

2

phase 0 represents

ventricular depolarization

3

rapid depolarization depends on initial entry of which electrolyte?

Na+

4

resting potential of myocardial cell

-90 mV

5

positive potential of myocardial cell

20 mV

6

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

QRS wave

7

ventricular repolarization occurs during which phases?

phases 1, 2, and 3

8

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

- Na+
- K+

9

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

- efflux of K+
- ENTRY of Ca++

10

phase 2 is AKA

plateau phase

11

what is phase 1 represented as on the ECG?

J point

12

what is phase 2 represented as on the ECG?

ST segment

13

what does phase 3 represent?

rapid repolarization to negative resting potential

14

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

- continued efflux of K+
- CLOSURE of Ca++

15

what is phase 3 represented as on the ECG?

T wave

16

how is the resting membrane potential maintained during phase 4?

- continued efflux of K+
- Na+/K+ ATPase pump

17

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

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