Which of the following is true concerning junctional rhythms? ...

[Chloeellawright]

Which of the following is true concerning junctional rhythms?
 
  a. They produce no P waves.
  b. They can produce inverted P waves.
  c. They are only generated high in the atrio-ventricular node.
  d. Their rates can vary from 60 beats/min to 80 beats/min.

Question 2

At what point in the figure do the semilunar valves close?
 
  a. A c. C
  b. B d. D

[taylorsonier]

Answer to Question 1

ANS: B
Junctional rhythms are impulses that originate in or near the atrioventricular node. The P wave may precede, coincide with, or follow the QRS, depending on the relative conduction times from the impulse's site of origin in the atrioventricular node to the atria and ventricles. Impulses gen-erated high in the atrioventricular node are likely to be associated with a P wave that occurs be-fore the QRS complex, whereas impulses generated low in the atrioventricular node result in a P wave that follows the QRS complex. Because of retrograde transmission of the impulse into the atria, the P wave appears inverted in the electrocardiogram leads that face the left side of the heart: leads II, III, and aVF.

Answer to Question 2

ANS: B
In the semilunar valves and aortic and pulmonic valves, closure is associated with the dicrotic notch on the aortic pressure tracing. See Figure 9-22.

[Chloeellawright]

Gracias!

Excellent