5: Normal heart rate changes

Question 1

What is R-R interval used to measure

Answer 1

Heart Rate

Question 2

What does sinus mean

Answer 2

All wave forms are present in correct sequence

Question 3

3 factors determining SA ode rate of depolarization

Answer 3

1. Maximum negative potential reached
2. Rate of phase 4 spontaneous depolarization
3. Threshold for Ca influx

Question 4

What do catecholamines do to SA node B-1 receptor activation

Answer 4

Increased Na and Ca channel opening

Increase heart rate

Question 5

What does actylcholin binding to the muscarinic receptor do

Answer 5

Decrease probability Na and Ca channels are open
Increase K channel opening
Decrease heart rates

Question 6

Normal sinus arrhythmia

Answer 6

fluctuation in parasymp

activated by inspiration which inhibits vagal parasymp outflow

Question 7

Pathological arrhythmias

Answer 7

Blockade of normal conduction path
Spontaneous generation of action potential
Ectopic pacemaker

Question 8

Ectopic pacemaker

Answer 8

Latent pacemaker develops faster rate than SA node

Question 9

Conduction reentry

Answer 9

Mechanism underlying deranged impulse propagation in cardiac muscle

Question 10

Arrhythmias attributed to reentry are

Answer 10

atrial and ventricular tachycardia