Electrical conduction in the heart

From the AV node, the action potential enters the atrioventricular (AV) bundle what happens?

atrioventricular (AV) bundle (also known as the bundle of His, pronounced HIZ). This bundle is the only site where action potentials can conduct from the atria to the ventricles. (Elsewhere, the fibrous skeleton of the heart electrically insulates the atria from the ventricles.) Atrioventricular (AV) bundle depolarizes in the interventricular septum.

Where does cardiac excitation normally begin?

begins in the sinoatrial (SA) node, located in the right atrial wall just inferior and lateral to the opening of the superior vena cava.

Atrioventricular node (AV) Inherent rhythm

40-50/min or 40-50APs/min (APs= action potentials)

Sinoatrial node (SA) inherent rhythm

90-100/min or 90-100APs/min (APs= action potentials)

By conducting along atrial muscle fibers, the action potential reaches the atrioventricular (AV) node what does the AV node do?

At the AV node, the action potential slows considerably as a result of various differences in cell structure in the AV node. This delay provides time for the atria to empty their blood into the ventricles.

What is pacemaker potential?

It is the result of the inability of the cell membrane to maintain a resting membrane potential, as soon as the membrane potential repolarizes, it immediately begins to depolarize again

What happens when pacemaker potential reaches threshold?

It triggers an action potential. Each action potential from the SA node propagates throughout both atria via gap junctions in the intercalated discs of atrial muscle fibers. Following the action potential, the two atria contract at the same time

Finally, the large-diameter __________

Purkinje fibers (pur-KIN-jē) rapidly conduct the action potential beginning at the apex of the heart upward to the remainder of the ventricular myocardium Then the ventricles contract, pushing the blood upward toward the semilunar valves. Ventricular systole occurs shortly after the Purkinje fibers depolarizes.

What does the atrioventricular border do?

border provides a fibrous skeleton insulator for action potential propagation

After propagating through the AV bundle, the action potential enters both ?

right and left bundle branches. The bundle branches extend through the interventricular septum toward the apex of the heart.