Guyton And Hall Textbook of Medical Physiology -12e by John E. Hall – Test Bank

Guyton And Hall Textbook of Medical Physiology -12e by John E. Hall – Test Bank

Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition

Chapter 10: Rhythmical Excitation of the Heart Test Bank

1. If the sinus node stops discharging, what is the expected heart rate (i beats/minute) if the A-V node takes over as the cardiac pacemaker? A. 15 B. 20 C. 35 D. 50 E. 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? A. 0.03 seconds B. 0.09 seconds C. 0.12 seconds D. 0.16 seconds E. 0.80 seconds ANS: A 3. Which of the following conditions at the S-A node will cause a decrease in heart rate? A. Increased sodium permeability B. Decreased acetylcholine levels C. Increased norepinephrine levels D. Increased potassium permeability E. Increased calcium permeability ANS: D 4. In which phase of the ventricular muscle action potential is the potassium permeability the highest? A. 0 B. 1 C. 2 D. 3 E. 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? A. 0.80 seconds B. 0.16 seconds C. 0.12 seconds D. 0.09 seconds E. 0.03 seconds ANS: C 6. A patient entered the local emergency room and had an EKG taken. The attending physician stated that the patient had an A-V nodal rhythm. What is the likely heart rate? A. 30/min B. 50/min C. 65/min D. 75/min E. 85/min ANS: B 7. Which of the following conditions at the S-A node will cause a decrease in heart rate? A. Increased sodium permeability B. Increased acetylcholine levels C. Increased norepinephrine levels D. Decreased potassium permeability E. Increased calcium permeability ANS: B 8. Which of the following conditions at the A-V node will cause a decrease in heart rate? A. Increased sodium permeability B. Decreased acetylcholine levels C. Increased norepinephrine levels D. Increased potassium permeability E. Increased calcium permeability ANS: D 9. If the S-A node discharges at 0.00 seconds, when will the action potential normally arrive at the ventricular septum? A. 0.22 seconds B. 0.16 seconds C. 0.12 seconds D. 0.09 seconds E. 0.03 seconds ANS: B 10. What is the normal total delay of the cardiac impulse in the A-V node + bundle? A. 0.22 seconds B. 0.18 seconds C. 0.16 seconds D. 0.13 seconds E. 0.09 seconds ANS: D 11. Which of the following are caused by acetylcholine? A. Hyperpolarization of the S-A node B. Depolarization of the A-V node C. Decreased permeability of the S-A node to potassium ions D. Increased heart rate E. Increased permeability of the cardiac muscle to calcium ions ANS: A 12. 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? A. 5 B. 30 C. 50 D. 70 E. 90 ANS: C 13. Sympathetic stimulation of the heart: A. Releases acetylcholine at the sympathetic endings B. Decreases sinus nodal discharge rate C. Decreases excitability of the heart D. Releases norepinephrine at the sympathetic endings E. Decreases cardiac contractility ANS: D