7.3.2 Cardiac Cycle

• What is the cardiac cycle?

  Sequence of events in heartbeat
• During diastole, the heart muscles relax
• During diastole, atrial and ventricular pressure are low.
• What happens to atrial pressure during systole?

  Remains low
• Stages of the cardiac cycle in order

  1️⃣ Atrial Systole

  2️⃣ Ventricular Systole

  3️⃣ Diastole
• What happens to atrial pressure during atrial systole?

  Increases briefly
• During ventricular systole, blood is forced into the pulmonary artery and aorta
• During diastole, both atrial and ventricular pressure decrease.
• Match the heart valves with their function:

  Atrioventricular Valves ↔️ Prevent backflow into atria

  Semilunar Valves ↔️ Prevent backflow into ventricles
• What triggers the opening of the atrioventricular valves?

  Atrial pressure > Ventricular pressure
• The proper opening and closing of heart valves ensure blood flows in the right direction
• Which neurotransmitter is released by the sympathetic nervous system to increase heart rate?

  Epinephrine
• The parasympathetic nervous system releases acetylcholine to decrease heart rate.
• The sympathetic nervous system increases both heart rate and force of contraction.