Cardiac cycle and output

• What is the cardiac cycle

  1 heart beat
• What is Systole

  Contraction
• The cardiac cycle consists of two phases

  Systole and Diastole
• What is Diastole

  Relaxation
• Label the diagram of the cardiac cycle

  X

  A) Atrial contraction

  B) Isovolumetric contraction

  C) Ventricular ejection

  D) Isovolumetric relaxation

  E) Ventricular filling

  
• Why does SV volume decrease once heart rate is over 200bpm

  The cardiac cycle would last 0.3 seconds. This leaves 0.2 seconds for atrial filling which is not enough.
• Which of the heart sounds are audible with a stethoscope

  The first and second.
• What causes heart sounds

  Turbulence when valves close.
• What causes the first heart sound

  Turbulence caused by the closure of the Atrioventricular valves
• What causes the second heart sound

  Turbulence when the Semilunar valves close
• When is the 3rd heart sound audible

  With specialist equipment
• When is the 4th heart sound audible

  When the ventricles are stiff
• What is cardiac diastole

  Atrial systole
• Describe atrial systole

  • Atrioventricular valves open
  • Semilunar valves are closed
  • Atria contract and blood enters the ventricles
• What is End diastolic pressure

  The volume in the ventricles before ejection
• What is the formula for EDV

  Ventricle volume + Atrial contribution (10% at rest)
• What is the units for volume of the heart

  ml
• What happens to atrial pressure in atrial systole

  Increases by a little
• What stage accounts for the EDV

  Atrial systole
• Describe isovolumetric contraction

  • Semilunar valves closed
  • Heart shape changes
  • Increase in intraventricular pressure closes atrioventricular valves [LUBB]
• Describe ventricular ejection 


  • Atrioventricular valves are closed
  • The atrium continues to fill
  • Intraventricular pressure is higher than aortic or pulmonary pressure
  • Causes the Semilumar valves to open
• What do heart sounds in ventricular ejection indicate

  A shunt is present or a valve disease.
• Describe reduced ejection

  • Atrioventricular valves are closed
  • Semilunar valves are open
  • No movement of blood through the semilunar valves
  • Ventricular muscles relax, so ventricular pressure decreases
  • Blood leaves the heart using kinetic energy
  • Atrial pressure continues to increase as the Atrium are still filling
• Describe isovolumetric relaxation 


  • Atrioventricular valves closed
  • Atrium pressure increases as venous blood returns
  • Semilunar valves close as ventricular pressure decreases [DUBB]
  • Ventricular volume remains the same
• Which semilunar valve closes first

  Aortic
• What is the end-systolic volume

  The volume in the ventricles after ejection
• Describe rapid filling

  • Atrioventricular valves open
  • Semilunar valves closed
  • Ventricle fill passively [3rd sound]
  • Atrium pressure falls
• Describe reduced filling

  Ventricles are at full stretch so pressure rises. Pressure in large vessels decreases as blood enters circulation.
• What are the two ventricular filling stages of the heart

  Rapid and reduced filling
• What are the two ventricular ejection stages

  Ventricular and reduced ejection
• What is the cardiac output

  How much blood the heart ejects per minute.
• What is the formula for cardiac output 


  CO = SV * HR
• What are the units for cardiac output

  ml/min
• What are the units for stroke volume

  ml/beat
• What are the units for heart rate

  beats/min
• What is the formula for stroke volume

  EDV -ESV
• How is cardiac output changed

  By regulation of the heart rate
• What are the two methods of regulating the heart rate

  Neural and ionic control.
• What happens to the heart when calcium levels are decreased 


  Weak contractions
• What is the role of potassium in the heart

  It is involved in muscle contraction and nerve conduction