18 Questions
What is the conduction velocity in the AV node?
0.01 to 0.05 m/s
What is the purpose of the delay in the AV node?
To permit the ventricles to fill with blood from the atria
What is the consequence of damage to the conducting system?
Decreased conduction velocity and diminished pressure generation
What is the conduction velocity in the His-Purkinje system?
2-4 m/s
What is the importance of the normal functioning conduction system?
To permit rapid, organized, near-synchronous depolarization and coordinated contraction of ventricular myocytes
What is the time delay between the SA node and the ventricles?
220 msec
What is the normal rate of discharge in the sinus node?
70-80 impulses/min
What is the function of the SA node in the heart?
To set the heart rate
What happens to the latent pacemaker when the SA node firing rate decreases or stops?
It takes over as the pacemaker of the heart
What determines how long it takes for the action potential to spread to various locations in the myocardium?
Conduction velocity
What is the shortest refractory period of all myocardial cells?
SA node
What is the term for the suppression of latent pacemakers by the faster firing rate of the SA node?
Overdrive suppression
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
During which phase of the cardiac action potential do potassium channels open, allowing potassium ions to leave the cell?
Repolarization phase
What is the ionic basis of the relative refractory period in cardiac action potentials?
Influx of sodium ions and efflux of potassium ions
What is the function of the atrioventricular node in the cardiac conduction system?
To delay the impulse to allow ventricles to fill before contracting
Which type of cardiac cells are specialized to spread action potentials rapidly?
Conducting cells
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
Understand the conduction of the action potential through the myocardium, including the roles of the SA node, AV node, and His-Purkinje system. Learn about the conduction velocities and delays in the cardiac conduction system.
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