Cardiac Action Potentials Flashcards Preview

Ex Phys Test 3 > Cardiac Action Potentials > Flashcards

Flashcards in Cardiac Action Potentials Deck (15)
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1
Q

Pacemaker Cells

A

(Slow APs)

2
Q

Pacemaker Potential

A

Unstable phase 4, Spontaneous Depolarization; Inward current caused by Na+ influx (IF), Inward Ca2+ current (ICa), Decreasing outward K+ current (IK)

3
Q

AP upstroke

A

Caused by L-VGCC Ca2+ influx, This SLOW AP triggers the FAST AP seen in the heart (This interaction what allows coordinated heart beat!)

4
Q

Repolarization

A

Increased K+ efflux (IK), Decreased Ca2+ Influx (ICa)

5
Q

Contractile Cells

A

(Fast APs); order of phases: 4, 0, 1, 2, 3

6
Q

Phase 4

A

Resting/resetting the RMP; Na+/K+ pump; RMP is -90mV

7
Q

Phase 0

A

Depolarization; Influx of Na+ through FAST Na+ channels

8
Q

Phase 1:

A

Early Rapid Repolarization;

FAST Na+ channels close, K+ efflux

9
Q

Phase 2

A

Slow Repolarization (plateau phase); Purpose of plateau is to extend AP in cardiac muscle cell is as long as the time the heart is contracting to prevent tetanus, K+ efflux, influx of Ca2+ & Na+ (SLOW Na+ channels)

10
Q

Phase 3

A

Final Rapid Repolarization; K+ efflux, Ca2+ & SLOW Na+ channels close

11
Q

Normal Pacemakers

A

SA node; normally suppresses other “ectopic” foci

12
Q

Electrical Conduction System Step 1

A

Action potentials originate in the SA node (pacemaker), and travel across the wall of the atrium to the AV node

13
Q

Electrical Conduction System Step 2

A

Action potentials pass through the AV node and along the atrioventricular bundle, which extends from the AV node through the fibrous skeleton into the interventricular septum

14
Q

Electrical Conduction System Step 3

A

The AV bundle divides into right and left bundle branches and action potentials descend to the apex of each ventricle along the bundle branches

15
Q

Electrical Conduction System Step 4

A

Action potentials are carried by the Purkinje fibers from the bundle branches to the ventricular walls