Cardiac Cycle

• Diastole


  relaxing
• systole


  contracting
• why do the tricuspid valve open

  there is a higher pressure in the right atrium compared to the right ventricle
• why do the bicuspid valve open

  when there is a higher pressure in the left atrium compared to the left ventricle
• why do the tricuspid valve close

  when there is a higher pressure in the ventricles compared to the atrium
• when do the semilunar valves open

  when there is a higher pressure in the ventricles compared to the arteries
• why do the semilunar valves close

  when there is a higher pressure in the arteries compared to the ventricles
• Define the cardiac output

  the volume of blood that leaves one ventricle in one minute
• equation for cardiac output

  heart rate X stroke volume
• Heart rate

  the beats of the heart per minute
• Stroke volume

  Volume of blood that leaves the heart every minute
• Atria diastole

  Both the artia and the ventricular muscular walls are relaxed, Blood enters the atria from the veins (vena cava and the pulmonary vein) The pressure and volume of the artia at this point increase
• Atria systole

  The atria muscular walls contract this increases the pressure of the atria the volume of the atria decreases. This causes the atrioventricular valves to open, The blood flows into the ventricles in ventricular diastole
• ventricular systole

  The ventricular walls contract this causes the pressure of the ventricles to increase more than the pressure in the atria, the volume decreases. This causes the atrioventricular valves to close and the semi-lunar valves open, The blood is then passed into the arteries. The pressure of the arteries increases and exceeds the pressure in the ventricles the semi-lunar valves close