Cardiac conduction system

• What is the function of the sinoatrial (SA) node in the cardiac conduction system?

  The SA node is the heart's natural pacemaker that initiates each heartbeat.
• Where is the sinoatrial (SA) node located?

  The SA node is located in the right atrium of the heart.
• What role does the atrioventricular (AV) node play in the cardiac conduction system?

  The AV node acts as a gatekeeper that briefly delays the electrical signal.
• Where is the atrioventricular (AV) node situated?

  The AV node is situated between the atria and ventricles.
• What happens when the electrical signal travels down the bundle of His?

  The signal divides into left and right branches.
• What are Purkinje fibres responsible for in the cardiac conduction system?

  Purkinje fibres rapidly transmit the electrical signal throughout the ventricle walls.
• What is the effect of Purkinje fibres transmitting electrical signals?

  They cause the ventricles to contract forcefully and pump blood out to the body.
• How does the cardiac conduction system respond during exercise?

  • Increased heart rate due to sympathetic nervous system activation
  • Enhanced conduction speed through the AV node
  • Stronger contractions from the Purkinje fibres
• What neurotransmitters are released by the sympathetic nervous system during exercise?

  Norepinephrine (noradrenaline) and epinephrine (adrenaline).
• How does the sympathetic nervous system affect the SA node?

  It increases the rate of electrical impulses, speeding up the heart rate.
• What is the role of the parasympathetic nervous system (PNS) in heart rate regulation?

  The PNS promotes rest and recovery, slowing down the heart rate.
• What neurotransmitter does the vagus nerve release to slow down the heart rate?

  Acetylcholine.
• How does the PNS affect the AV node?

  The PNS slows the speed of electrical conduction through the AV node.
• What is the dynamic balance between the sympathetic and parasympathetic nervous systems?

  • At rest, the PNS dominates, keeping heart rate low.
  • During exercise or stress, the SNS takes over, increasing heart rate.
  • After activity, the PNS gradually regains control to lower heart rate back to normal.
• Why is understanding the balance between the SNS and PNS important for sports science students?

  It helps optimize athletic performance and improve heart response to exercise.
• What effect does endurance training have on the PNS response?

  It enhances the PNS response, leading to a lower resting heart rate.
• What are indicators of good cardiovascular health related to heart rate?

  A lower resting heart rate and greater heart rate variability.