Biology cardiac cycle

• Purpose of the purkyne tissue

  Runs down the septum to the base and allows the waves of excitation to speed up the walls of the ventricles
• Explain the atrioventricular node

  Node on top of the septum separating the two ventricles - picks up waves of excitation and conducts its to a specialised tissue called the purkyne tissue
• Explain the sinoatrial node

  Small patch of tissue that sends out waves of electrical excitation at regular intervals to initiate contractions. This is the pacemaker
• The heart muscle can initiate its own reaction what is this called ?


  Myogenic
• What is the function of the cords

  Prevent valves inverting
• What is the correct term for the cords attached to the valves

  Tendons
• What is the function of the bicuspid and tricuspid valve ?

  Prevent back flow of blood from the ventricles to the atria when the ventricles contract
• Where do you find the tricuspid valve ?

  Right atrium
• Where do find the bicuspid valve ?

  Left atrium
• What is the function of the semi lunar valves ?

  Prevent backflow of blood from the arteries to the ventricles when the ventricles relax
• Where do you find the semi lunar valves in the heart ?
• Comment on the out out of the left and right ventricles

  Compare pressure, contraction, distance and force
• What is the function of the coronary artery ?

  
• Stages of 2nd diastole

  Heart muscle relaxes again

  Pressure in chambers reduces

  Blood pressure in arteries is greater than in ventricles - this forces semi lunar valves shut to prevent backflow of blood from arteries in ventricles

  Cycle continues !
• Stages of ventricular systole

  Ventricles contract

  This reduces volume and increases pressure in ventricles

  When the pressure in the ventricles is more than in the atria

  Bicuspid and tricuspid vale are forced shut which prevent back flow of blood to atria

  Tendons prevent valves inverting

  Pressure in ventricles greater than in arteries so semi lunar valves are forced open

  Blood flow out the ventricles into the arteries
• Stages in atrial systole

  Muscles in wall of atria contract

  Reduces volume and increase pressure in atria

  Bicuspid and tricuspid are forced open fully

  Blood from the atria is forced into the ventricles
• Stages of 1st diastole

  Heart muscle relax

  Blood enters the left and right atria (veins)

  Pressure in the atria increases

  Bicuspid / tricuspid valves open slightly

  Blood starts to enter ventricle
• What are the 4 stages of cardiac cycle

  Diastole,

  atrial systole

  Ventricular systole

  Diastole