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1. Cardiac cycle
HUMAN ANATOMY AND PHYSIOLOGY
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2. Introduction
 The function of the heart is to maintain a
constant circulation of blood through out the
body.
 The heart acts as a pump and its action consist
of series of events known as the cardias cycle.
 During each heart beat or cardiac cycle, the
heart contracts and then relaxes.
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3. Introduction
 The period of contraction is called systole and
the of relaxation called diastole.
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4. Event of cardiac cycle
 It is classified into two types of cardiac cycle.
1). Atrial events
2). Ventricular event
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6. Atrial systole
 SA node wave of contraction spreads through
the atria and the bicuspid and tricuspid valves
open up and thus pumping blood from the atria
into ventricles.
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7. ventricular systole
 Next, AV node wave contraction spreads through
both the ventricles.
 The bicuspid and tricuspid valves close and
produce the first heart sound lub.
 As the ventricles contract blood flows aorta from
the left vernicle and pulmonary artery from the
right ventricle.
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8. ventricular Diastole
 As ventricles relax both semilunar valves close with
a sound of dub.
 The pressure of the atrium both the bicuspid and
tricuspid valves open and the blood again flows
into the ventricles.
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9. Joint Diastole
 Before the cycle starts again atria and ventricles
are relaxed this state is known as the joint diastole
during the state blood flow from superior and
inferior vena cava into the atria to the ventricles.
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10. Thank you
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