Electrical conduction in myocardial cells

Question 1

Which cells spontaneously fire action potentaials.

Answer 1

autorhythmic cells

Question 2

Depolarizations of autorhythmic cells then spread rapidly to adjacent contractile cells through

Answer 2

gap junctions

Question 3

also called pacemaker potential

Answer 3

prepotential

Question 4

What is prepotential

Answer 4

Also called pacemaker potential
Resting potential of conducting cells
Gradually depolarizes toward threshold
SA node depolarizes first, establishing heart rate

Question 5

Which node depolarizes first, establishig the heart rate

Answer 5

SA node

Question 6

For heart rate: SA node generate how many action potentials per minute? How much does the AV node generate

Answer 6

80-100 per minute

AV node generate 40-60 AP per minute

Question 7

What are the steps of the conducting system of the heart (5)

Answer 7

1. SA node depolarizes

2.Electrical activity goes rapidly to AV node via internodal pathways

3. depolarization spreads more slowly across atria. Conduction slows through AV node

4.Depolarizationmoves rapidly through ventricular conducting system to the apex of the heart

5. Depolarization wave spreads upward from the apex

Question 8

Bradycardia

Answer 8

abnormally slow heart rate

Question 9

Tachycardia

Answer 9

abnormally fast heart rate

Question 10

Abnormal cells
Generate high rate of action potentials
Bypass conducting system
Disrupt ventricular contractions

Answer 10

Ectopic pacemaker

Question 11

Ectopic pacemaker

Answer 11

Abnormal cells
Generate high rate of action potentials
Bypass conducting system
Disrupt ventricular contractions

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