Arrhythmia

Question 1

Non-pacemaker (contractile myocytes)

Ventricular Action Potential

Answer 1

atria
ventricles
Bundle of His
Purkinje fibers

Question 2

Pacemaker (conducting myocytes)
SA Node Action Potential

Answer 2

SA node

Question 3

a function of the unequal distribution of ions

– sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl−)

– across the plasma membrane and the relative permeability of the membrane to each ion

Answer 3

Cardiac Action Potential

Question 4

• Na+ enter the cell through fast Na+ channels
• cell membrane changes charge from negative to positive

Answer 4

Phase 0 / Rapid depolarization

Question 5

• as fast as Na+ channels close K+ leave the cell through the K+ channels
• cell rapidly repolarize

Answer 5

Phase 1 / Early or Initial Repolarization

Question 6

• Ca2+ enter the cells through slow L-type Ca2+ channels, while K+ exit through the K+ channels
• cell membrane’s electrical activity temporarily stabilizes = action potential reaches a plateau

Answer 6

Phase 2 / Plateau