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Cardiac Conduction

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Cardiac Conduction

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Module: Distribution Activity: Animations Title: Cardiac Conduction

1. What is the function of the Conduction System? All cells must contract in a specific sequence. This sequence is determined by the pathway known as the conduction system.

2. Cardiac cells are connective and autorhythmic. What does this mean? Connective cells, action potentials, (excitatory signals) can propagate from one cell to another via gap junctions. Autorhythmic cells can excite themselves spontaneously without stimulation of the nervous system and contract at a regular rhythm.

3. Cells from different parts of the heart’s conduction system have different natural rhythms. What are the average beats per minute at each of the following parts of the heart?

a. Sinoatrial Node (SA) 100 bpm

b. Atrioventricular Node (AV) 40-50 bpm

c. Ventricles 20-40 bpm

4. What is the function of the SA Node? Describe how this happens. The healthy heart’s pacemaker, SA node triggers contraction because it depolarizes at a faster rate than other parts of the conduction system.

5. The AV node starts a series of events that leads to ventricular contraction. Describe this series of events. The AV node is the only connection between the atria and ventricles, once the signal passes the AV node, it propagates through the ventricular portion of the conduction system.

AV bundle and left and right bundle branches, apex of the heart, larger diameter conduction myofibers (purkinje fibers), the conduction myofibers then directly stimulate the cardiac cells in the ventricles to contract. During ventricular contraction blood is squeezed out from the apex to the base and into the

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