Generation/conduction heartbeat & EKG

Question 1

Effect of sympathetic on SA conduction

Answer 1

lower threshold, faster diastolic depolarization

Question 2

Effect of parasympathetic on SA conduction

Answer 2

decrease rate of diastolic depolarization, more negative maximum diastolic potential, higher threshold

Question 3

Hyperkalemia on HR

Answer 3

depolarizes membrane, decreasing activation of If, (slower phase 4) = slower HR

Question 4

Hypokalemia on HR

Answer 4

hyperpolarization of membrane potential, increase If activation (faster phase 4) = higher HR

Question 5

Hypoxia on HR

Answer 5

depolarization of resting membrane potential bc of inhibition of Na/K ATPase, decreasing If activation = slower HR

Question 6

Hyperthyroidism on HR

Answer 6

T3 increases If via increasing expression of HCN channels - faster HR

Question 7

Body temp on HR

Answer 7

increases due to ion channel kinetics, 10bpm per Centigrade degree

Question 8

EKG interval tested on all drugs

Answer 8

QT interval

Question 9

P wave

Answer 9

atrial depolarization

Question 10

PR interval

Answer 10

conduction through AV node

Question 11

QRS

Answer 11

conduction through the bundle of His and L/R bundle branches

Question 12

T wave

Answer 12

ventricle repolarization

Question 13

QT interval

Answer 13

Onset of ventricular depolarization to termination of Ventricular repolarization