Cardiac Excitation Flashcards Preview

S&F III: Exam 1 > Cardiac Excitation > Flashcards

Flashcards in Cardiac Excitation Deck (14):
1

what determines rate of SA firing?

rate of phase 4 depol (decreases time)
max neg. diastolic potential (increases time)
threshold potential (less neg, dec time)

2

how does SNS control excitation?

increases HR by increasing # of diastolic depol events
(B1 increases, increases Phase 4)
**all of heart**

3

how does PNS control excitation

**pacemaker cells**
decreases HR by hyperpolarizing thru ACh and K efflux

4

what is overdrive suppression

whatever pacemaker fires faster takes over as primary (usually SA)

5

escape rhythm

impulse initiated by not SA

6

Junctional escape

AV node or prox. bundle of His (40-60 bpm)

7

Ventricular escape

purkinje fibers or RT/LT AV bundles
*PNS* 15-40 bpm

8

Ectopic rhythm

premie beat from latents due to electrolyte change or drugs by increase in Catecholamine concentration

*non pacemaker too*

9

early afterdepolarizations

phase 2&3--> torsades de pointes
prolonged action potential

10

delayed afterdepolarizations

post repolarization; digitoxin, TACHY

11

Conduction block

common in AV, induces escape rhythm
no excitability due to ischemia

12

Reentry

due to unidirectional block, reexcites retropath

13

anatomical reentry

AVNRT, WPW Syndrome, VT from MI, Atrial Flutter
**monomorphic tachy on EKG**

14

functional reentry

no fixed path
*polymorphic tachy** the fibs