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Cardiac Conduction System

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Questions and Answers

What is the conduction velocity in the AV node?

0.01 to 0.05 m/s (correct)
0.1-0.5 m/s
2-4 m/s
1-2 m/s

What is the purpose of the delay in the AV node?

To slow down the heart rate
To permit the ventricles to fill with blood from the atria (correct)
To allow the atria to fill with blood
To ensure the ventricles contract quickly

What is the consequence of damage to the conducting system?

Decreased conduction velocity and diminished pressure generation (correct)
Increased conduction velocity
Increased refractory period
Faster heart rate

What is the conduction velocity in the His-Purkinje system?

2-4 m/s (B) Signup and view all the answers

What is the importance of the normal functioning conduction system?

To permit rapid, organized, near-synchronous depolarization and coordinated contraction of ventricular myocytes (A) Signup and view all the answers

What is the time delay between the SA node and the ventricles?

220 msec (B) Signup and view all the answers

What is the normal rate of discharge in the sinus node?

70-80 impulses/min (D) Signup and view all the answers

What is the function of the SA node in the heart?

To set the heart rate (A) Signup and view all the answers

What happens to the latent pacemaker when the SA node firing rate decreases or stops?

It takes over as the pacemaker of the heart (D) Signup and view all the answers

What determines how long it takes for the action potential to spread to various locations in the myocardium?

Conduction velocity (D) Signup and view all the answers

What is the shortest refractory period of all myocardial cells?

SA node (A) Signup and view all the answers

What is the term for the suppression of latent pacemakers by the faster firing rate of the SA node?

Overdrive suppression (A) Signup and view all the answers

What is the primary function of the internodal pathway in the cardiac conduction system?

To transmit the impulse from the sinoatrial node to the atrioventricular node (C) Signup and view all the answers

During which phase of the cardiac action potential do potassium channels open, allowing potassium ions to leave the cell?

Repolarization phase (A) Signup and view all the answers

What is the ionic basis of the relative refractory period in cardiac action potentials?

Influx of sodium ions and efflux of potassium ions (C) Signup and view all the answers

What is the function of the atrioventricular node in the cardiac conduction system?

To delay the impulse to allow ventricles to fill before contracting (C) Signup and view all the answers

Which type of cardiac cells are specialized to spread action potentials rapidly?

Conducting cells (C) Signup and view all the answers

What is the function of the bundle of His in the cardiac conduction system?

To transmit the impulse from the atrioventricular node to the ventricles (D) Signup and view all the answers

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