D structure of heart and cardiac conduction system

• the septum breaks heart into two sides
• atrium have thinner muscular walls as they only push blood down into ventricles
• ventricles have thicker muscular walls as they pump blood with greater force out of heart
• which side of heart is larger?

  left
• valves regulate blood flow by ensuring it moves in one direction and preventing back flow
• tricuspid valve

  located between right atrium and right ventricle
• bicuspid valve

  located between left atrium and left ventricle
• semi-lunar valves

  located between

  • right ventricle and left ventricle
  • pulmonary artery and aorta
• myogenic

  capacity of heart to generate its own impulse
• sinoatrial node

  cardiac muscle found in wall of right atrium that generates heartbeat
• the sinoatrial node is also known as pacemaker
• atrioventricular node

  relays impulse between upper and lower sections of heart
• bundle of his

  transmit electrical impulse from atrioventricular node to ventricles via bundle branches and purkinje fibres
• purkinje fibres

  muscle fibres spread through ought ventricles that conduct an electrical impulse
• cardiac conduction system

  1. electrical impulse from sinoatrial node spreads through atria as wave of excitation
  2. atria contract forcing blood into ventricles
  3. impulse passes through atrioventricular node
  4. atrioventricular node delays impulse for 0.1s to enable atria to fully contract before ventricular systole
  5. impulse passes through bundle of his within septum, bundle of his separates into purkinje fibres spread through ought ventricles causing them to contract.