Cardiac Conduction

735 Words Jan 11th, 2016 3 Pages
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
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The signal moves quickly from the SA node through the atria where it experiences a slight delay when it reaches the AV node and it must pass into fibers with smaller diameters. The signal then quickly resumes along its path through the AV bundle branches apex and base of the ventricles contraction begins.

7. What happens at each of the following points of a normal ECG?

P – Atrial excitation (atrial depolarization).

QRS – Ventricular excitation (ventricular depolarization).

T – End of ventricular excitation (ventricular repolarization).

8. Contrast a healthy heart ECG with an abnormal one in which ventricular excitation is independent of atrial excitation (P waves). The sequence of depolarization and repolarization can be seen in a normal electrocardiogram usually called the ECG. The electrocardiogram can also show problems with the conduction system. Look at this trace showing complete heart block by comparing the QRS waves to the P waves. You can see that ventricular excitation is independent of atrial excitation. The pace of ventricular excitation is being sent by the ventricles slower natural rhythm not by stipulation from the SA node atria.

9. Contrast the resting potential of typical myocardial cells with that of SA nodaL cells. A typical contractile cell in the
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