Cardiac cycle

• Who is the presenter of the A Level Biology video on the cardiac cycle?

  Miss Esther
• What does the cardiac cycle focus on?

  Volume and pressure changes in the heart
• What should you watch before the cardiac cycle video?

  The video on heart structure
• Why is it important to learn heart structures before the cardiac cycle?

  It helps understand the cardiac cycle better
• What are the three key stages of the cardiac cycle?

  Diastole, atrial systole, ventricular systole
• What does diastole mean in the context of the cardiac cycle?

  Relaxation of the heart muscles
• What does systole mean in the context of the cardiac cycle?

  Contraction of the heart muscles
• What happens to the volume of the atria during atrial systole?

  The volume decreases as they contract
• What causes the atrioventricular valves to open during atrial systole?

  Increased pressure in the atria
• What happens during ventricular systole?

  The ventricles contract and pressure increases
• What is the role of the semilunar valves during ventricular systole?

  They open to allow blood to exit the heart
• How is cardiac output calculated?

  Heart rate times stroke volume
• What is stroke volume?

  Volume of blood leaving the heart per beat
• What do the valves in the heart ensure?

  Unidirectional flow of blood
• What are the two sets of valves in the heart?

  Semilunar and atrioventricular valves
• When do the atrioventricular valves open?

  When pressure is higher in the atria
• What causes the semilunar valves to close?

  Higher pressure in the arteries compared to ventricles
• How do pressure changes affect the opening and closing of valves?

  Higher pressure behind opens, higher pressure in front closes
• What happens to the pressure in the ventricles during ventricular systole?

  The pressure significantly increases
• What is the relationship between atrial systole and ventricular pressure?

  Atrial pressure must exceed ventricular pressure to open valves
• What are the stages of the cardiac cycle and their effects on heart chambers?

  • Diastole: Both chambers relax, volume increases
  • Atrial Systole: Atria contract, volume decreases, pressure increases
  • Ventricular Systole: Ventricles contract, volume decreases, pressure increases
• How do the valves function during the cardiac cycle?

  • Atrioventricular valves: Open when atrial pressure > ventricular pressure
  • Semilunar valves: Open when ventricular pressure > arterial pressure
  • Prevent backflow of blood
• What happens to pressure and volume during the cardiac cycle?

  • Atrial systole: Pressure increases in atria, volume decreases
  • Ventricular systole: Pressure increases in ventricles, volume decreases
  • Diastole: Pressure decreases in both chambers, volume increases
• How would you interpret a pressure change graph of the cardiac cycle?

  • Identify when valves open/close based on pressure differences
  • Relate pressure changes to systole and diastole phases
  • Visualize the flow of blood through the heart
• What is the significance of the thickness of the ventricular walls?

  • Allows for strong contractions
  • Generates high pressure to pump blood
  • Essential for effective circulation
• What is the role of the cardiac cycle in the heart's function?

  • Coordinates heartbeats
  • Ensures efficient blood flow
  • Maintains proper pressure in chambers