Exam 4 Review - Basic heart function

Sinoatrial (SA) node

Generates electrical impulses throughout heart to set normal heart rate and rhythm. Forces atria to push blood into ventricles.

Atrioventricular (AV) node

Electrical gateway between atria and ventricles. Receives signal from SA node and delays it briefly to allow atria time to empty into ventricles.

Right and left bundle branches

Carries electrical signal from AV node to ventricles, causing ventricular contraction.

Purkinje fibers

Carries electrical signals from Bundle of His to the bottom of the heart.

Depolarization

Shift of electrical potential of a cell membrane from a negative to a more positive value.

Repolarization

Shift in the electrical potential of a cell membrane from a positive to a more negative value.

Preload

The amount of stretch caused by the blood volume in the ventricles just prior to contraction.

Afterload

Amount of resistance and pressure the heart must overcome to pump blood out to the rest of the body.