CV 2: Cardiac Cell Electrophysiology

Atrium and Ventricles APs

SAN & AVN APs

MP and APs (General)

Phase 0: Upstroke

Phase 1: Early repolarization

Phase 2: Plateau

Phase 3: Repolarisation

Phase 4: Resting

Na Influx

Na close

Transient outward K+

L-type Ca channels

Delayed Rectifier K+ Channels

Rapidly activating

Slowly activating

Inward Rectifying K+ Channels

Pumps

3Na: 2K pump

3Na:1Ca2+ pump

ATP-driven Ca2+ pump

Slow and small Upstroke

L-Type Ca 2+

No early repolarization

No plateau

L-type Ca2+ are already closed

No transient K+ channels

No resting potential

Diastolic depolarization

Hyperpolarization-activated inward current channels

Depolarization from Na-Ca exchanger

T-type Ca2+ channels

ANS

Sympathetic

Parasympathetic

increase activity

Decrease activity via acetylcholine regulated K+ channels