The promoters for Classes I and II, 5S and tRNA genes, are internal; they lie downstream of the start point.

TLS Online TPP Program

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#Unit 7. System Physiology – Animal

Each cardiac cycle is initiated by spontaneous generation of an action potential in the sinus node.

TLS Online TPP Program

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#Unit 7. System Physiology – Animal

Period of relaxation called diastole, during which the heart fills with blood A period of contraction called systole

TLS Online TPP Program

#Id: 5300

#Unit 7. System Physiology – Animal

The total duration of the cardiac cycle, including systole and diastole, is the reciprocal of the heart rate.

TLS Online TPP Program

#Id: 5301

#Unit 7. System Physiology – Animal

Atrial systole 

Preceded by the depolarization of the atria

Contraction of the atrium causes an increase in atrial pressure.

TLS Online TPP Program

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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.

TLS Online TPP Program

#Id: 5303

#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.