Excessive vagal activation of the AV node leads to what effect on conduction velocity?

Unlock all questions

This demo includes only 20 questions. Upgrade to access hundreds of questions, flashcards, exam simulations, and disable ads.

Full question bankExam simulationsFlashcards
From $24.99Unlock all

Prepare for the Cardiac Electrophysiology Test. Study with interactive quizzes and multiple choice questions. Each question includes helpful hints and detailed explanations. Start your journey to success on your cardiac exam now!

Multiple Choice

Excessive vagal activation of the AV node leads to what effect on conduction velocity?

Explanation:
Excessive vagal activation slows conduction through the AV node. Parasympathetic input releases acetylcholine, which binds to M2 receptors on AV nodal cells. This activates inward-rectifier potassium channels, increasing K+ efflux, hyperpolarizing the cells, and reducing the slope of phase 4, making it harder for impulses to propagate. At the same time, acetylcholine inhibits adenylate cyclase, lowering cAMP and reducing L-type calcium current, which is crucial for AV nodal conduction. The net result is a slower conduction velocity and a longer PR interval; in extreme vagal tone, AV block can occur.

Excessive vagal activation slows conduction through the AV node. Parasympathetic input releases acetylcholine, which binds to M2 receptors on AV nodal cells. This activates inward-rectifier potassium channels, increasing K+ efflux, hyperpolarizing the cells, and reducing the slope of phase 4, making it harder for impulses to propagate. At the same time, acetylcholine inhibits adenylate cyclase, lowering cAMP and reducing L-type calcium current, which is crucial for AV nodal conduction. The net result is a slower conduction velocity and a longer PR interval; in extreme vagal tone, AV block can occur.

More Multiple Choice Questions
Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy