Cardiac Cycle

Description of the Cardiac Cycle:

There are 4 phases in the cardiac cycle:

• 1st Diastole period- the deoxygenated blood goes into the right atrium and the AV node sends a signal for the heart to contract which leads the blood through the right atrium to the right ventricle
• 1st Systole period- the ventricles receive impulses from the purkinje fibers which causes them to contract. Then the blood travels to the pulmonary artery and towards the lungs to become oxygenated
• 2nd Diastole period-  the oxygenated blood within the pulmonary veins goes into the left atrium. Then the SA node sends a signal for the atria to contract which leads to the blood going to the left ventricle.
• 2nd Systole period- the ventricles receive signals and contract so the blood is pushed into the aorta which branches out into the rest of the body to provide oxygen.

• Systole- is the contraction of a heart chamber 

• Diastole- is the relaxation of a heart chamber

Normal Ranges:

• QRS Complex- Represents the onset of ventricular depolarization (x< 0.12 seconds)

• PR Interval- represents the conduction of time from the beginning of the atrial ex-citation to the beginning of the ventricular excitation. ( between 0.12 - 0.20 seconds)

• QT- represents the beginning of the ventricular depolarization to the end of the ventricular repolarization. (x< 0.40 seconds)