Chapter 10: Rhythmical Excitation of the Heart

Chapter 10: Rhythmical Excitation of the Heart

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

1. If the sinus node stops discharging, what is the expected heart rate (in beats/minute) if the A-V node takes over as the cardiac pacemaker?
2. 15

1. 20
2. 35
3. 50
4. 72

ANS: D

2. If the S-A node discharges at 0.00 seconds, when will the action potential normally arrive at the A-V node?
3. 03 seconds

1. 0.09 seconds
2. 0.12 seconds
3. 0.16 seconds
4. 0.80 seconds

ANS: A

3. Which of the following conditions at the S-A node will cause a decrease in heart rate?

1. Increased sodium permeability
2. Decreased acetylcholine levels
3. Increased norepinephrine levels
4. Increased potassium permeability
5. Increased calcium permeability

ANS: D

4. In which phase of the ventricular muscle action potential is the potassium permeability the highest?

1. 0
2. 1
3. 2
4. 3
5. 4

ANS: D

5. If the S-A node discharges at 0.00 seconds, when will the action potential normally arrive at the A-V bundle?
6. 80 seconds

1. 0.16 seconds
2. 0.12 seconds
3. 0.09 seconds
4. 0.03 seconds

ANS: C