Regulating the Heartbeat

• What are the 6 components involved in the regulation of the heartbeat?

  Bundle of His

  AVN

  SAN

  Wave of Depolerisation

  Delay

  Purkynjie fibres
• What does SAN Stand for?

  Sinoatrial node
• What does AVN Stand for?

  Atrioventricular Node
• Why is heart tissue known as myogenic

  It is able to initiate its own contraction within the muscle cells, meaning it isn’t dependent on external signals from the nervous system.
• How does the SAN Work?

  1. The sinoatrial node produces a wave of Depolerisation. The SAN sends a wave of Deolerisation to the atrial walls which causes the atria to contract at approximately the same time.
• After the SAN has sent a W.O.D What happenes?

  1. The signal passes down the atrial septum. A thin layer of collagen tissue at the base of the atria prevents the wave of electricity from reaching the ventricles. Instead, the SAN passes the electricity to the atrioventricular node (AVN), located between both the atria.
• What happenes once the AVN has recived the wave?

  1. The atrioventricular node (AVN) conducts the signal to the ventricles. The AVN passes the wave of electricity down the nerves of the bundle of His. There is a slight delay in this, so the muscle of the ventricles don’t contract before the atria can fully empty.
• What does the Bundle of His do with this wave?

  1. The bundle of His transmits the wave to the base of the heart. The bundle is comprised of muscle fibres that extend from the AVN to the apex (bottom) of the heart, where it splits into the Purkinje fibres and branches up into each ventricle.
• What does the Purkynjie Fibres do with the wave?

  1. The electricity passes up the Purkinje fibres. This allows the ventricles to contract from the base up, which allows the ventricles to fully empty, pushing the blood into the aorta and pulmonary artery.
• Label the diagram

  A) Sinoatriol Node

  B) Atrioventricular Node

  C) Purkynjie Fibres

  D) Bundle of His