Arrhythmias

Question 1

At what phase does diastole occur?

Answer 1

phase 4

Question 2

At what phase does the plateau form

Answer 2

phase 2

Question 3

at what phase does repolarization take place

Answer 3

phase 3

Question 4

At what phase does early, fast repolarization occur?

Answer 4

phase 1

Question 5

at what phase does upstroke occur?

Answer 5

phase 0

Question 6

what are the 3 major phases of an SA nodal cell, and what occurs at each?
what type of current is in each?

Answer 6

phase 4 = slow depolarization = pacemaker current
phase 0 = action potential upstroke = inward Ca
phase 3 = repolarization = outward K current

Question 7

what are the phases of a ventricular cell, and what occurs at each?
what type of current is in each?

Answer 7

Phase 4 = resting potential = equal currents in and out
Phase 0 = rapid depolarization = Inward Na
Phase 1 = early phase of repolarization = decrease of inward Na,
and outflow of K ions
Phase 2 = plateau = balance of inward Ca and outward K
phase 3 = rapid repolarization = decrease inward Ca,
large increase of outward K

Question 8

when what channel opens, the heart moves rapidly towards 150 mV?
Is this depolarization or repolarization?

Answer 8

Calcium channel

depolarization

Question 9

when what channel opens, the heart moves rapidly towards -94 mV?
Is this depolarization or repolarization?

Answer 9

Potassium Channel

repolarization

Question 10

what is considered a transient phase in ventricle AP?

Answer 10

phase 1

Question 11

name the 3 types of cardiac pacemaker cells

Answer 11

1. SA node = 60-100 bpm
2. AV node = 50-60 bpm
3. ventricular myocytes = 30-40 bpm

Question 12

non-pacemaker electrical cardiac cells have what two characteristics.

Answer 12

1. can’t initiate AP’s

2. contract in response to depolarization around them

Question 13

what has a slow conduction of about 0.15 seconds?

why is it slow

Answer 13

AV node

allow time for atrial contraction to move blood to ventricle

Question 14

what are the characteristics of AV node electric impulses

Answer 14

1. slow conduction

2. allows atrial contraction

Question 15

What part of cardiac electric path has a fast conduction time?

Answer 15

his-purkinje system

impulse spreads throughout entire ventricle

Question 16

ECG meaures what?

Answer 16

body surface manifestation of the overall electrical activity of the heart

Question 17

what measures atrial depolarization in an ECG

Answer 17

P wave

Question 18

what measures ventricular depolarization in an ECG

Answer 18

QRS complex

Question 19

What measures ventricular repolarization in an ECG

Answer 19

T wave

Question 20

describe what part of an ECG the PR interval describes?

what do problems here indicate?

Answer 20

starts at front of P wave, ends at end of R, beginning of S

problems here diagnose problems w/ AV node

Question 21

what interval of an ECG measures entire ventricular AP

Answer 21

QT interval

Question 22

what segment of an ECG measures plateau phase?

Answer 22

ST segment