Conducting cells are specialized muscle cells which function to rapidly spread action potentials over the entire myocardium.

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#Unit 7. System Physiology – Animal

Atrial systole 

Preceded by the depolarization of the atria

Contraction of the atrium causes an increase in atrial pressure.

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#Unit 7. System Physiology – Animal

Atrial systole

The P wave is caused by spread of depolarization through the atria and is followed by atrial contraction.

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#Unit 7. System Physiology – Animal

Atrial systole 

Increase in atrial pressure is reflected back to the veins, it appears on the venous pulse record as the a wave.

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#Unit 7. System Physiology – Animal

Atrial systole 

ventricle is relaxed, & because the AV valve is open, the ventricle is filling with blood from the atrium, even prior to atrial systole.

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#Unit 7. System Physiology – Animal

When blood is actively ejected from the atrium to the ventricle through the open AV valves. The corresponding “blip” in ventricular pressure reflects this additional volume added to the ventricle from atrial systole.

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#Unit 7. System Physiology – Animal

Fourth heart sound (S4)

Not audible in normal adults

Heard in ventricular hypertrophy, where ventricular compliance is decreased