What exactly does it mean when you hear the term Cardiac Cycle?

It is a period or cycle of time from the start of one heart beat to the start of the next. Chambers within the heart are all alternating periods of contractions and relaxations.
Did you know that the heart beats 100,000 times each day and pumps about 5 quarts of blood each minute! That would be equal to approximately 2,000 gallons of blood each day!

COORDINATION

The heart chambers cyclically contract and relax, which causes pressure on the blood within the chambers and will alternately increase and decrease.

• Blood flows continuously into both atria under low pressure
• Blood passes from atria to ventricles if the AV valves are open
• Ventricular filling is about 70% when both chambers are relaxing
• Ventricular filling is about 30% when the atria contract
• Ventricular contraction's
  
• Increases pressure
• AV valves close
• Semilunar valves open to permit blood

There are 2 main phases of the Heart.

• Systole
• Contraction of the heart which pushes the blood out of the chambers
• Normal Systolic Blood pressure should be about 120 mmhg
  
• Diastole
• Relaxation of the heart chambers
  
• Normal Diastolic blood pressure should be about 80 mmhg

Steal my BEATING heart

The heart has 4 normal beats, accompanied by 2 familiar heart beat sounds "Lubb Dupp" and 2 minor sounds.

• "Lubb" signifies closing of the AV valves
• "Dupp" signifies closing of the semilunar valves

To hear certain valves in the heart more clearly the best places are:

1. The 2nd intercostal space to the right of the sternum
1. Aortic Semilunar valve can be heard at this spot
   
2. The 2nd intercostal space to the left of the sternum
1. Pulmonary semilunar valve can be heard at this spot
   
3. Right side of the inferior end of the sternum
1. Right AV valve
   
4. Near the apex of the heart
1. Left AV valve

CONDUCTION SYSTEM

There are collectives of specialized cells that are part of the hearts conduction system. These cells/muscle fibers are specialized to conduct muscle impulses to the contractile muscle cells of the myocardium.