Quiz

• What keeps the blood pumping through your arteries?

  The cardiac conduction system
• What is the role of the sinoatrial (SA) node?

  It acts as the pacemaker of the heart
• What are the main components of the cardiac conduction system?

  • Sinoatrial (SA) node
  • Atrioventricular (AV) node
  • Bundle of His
  • Right and left bundle branches
  • Purkinje fibers
• What color represents low oxygen blood in diagrams?

  Blue
• What color represents high oxygen blood in diagrams?

  Red
• How does blood flow from the right atrium to the lungs?

  Through the pulmonary artery
• What prevents the atria and ventricles from contracting simultaneously?

  The non-conductive fibrous tissue
• What is the function of the atrial and ventricular syncytium?

  They allow electrical connection among cardiac cells
• What is the significance of the delay in the AV node?

  It separates atrial contraction from ventricular contraction
• What is the bundle of His also known as?

  Atrioventricular bundle
• How do Purkinje fibers function in the heart?

  They spread the signal throughout the ventricles
• What are the phases of the cardiac cycle as represented in an ECG/EKG?

  • P-wave: Atrial depolarization
  • QRS complex: Ventricular depolarization
  • T-wave: Ventricular repolarization
• What does the P-wave in an ECG represent?

  Atrial depolarization
• What does the QRS complex in an ECG represent?

  Ventricular depolarization
• What does the T-wave in an ECG represent?

  Ventricular repolarization
• How does the cardiac conduction system ensure coordinated heart contractions?

  • SA node initiates heartbeat
  • Signals travel through internodal pathways
  • AV node introduces delay
  • Bundle of His and branches transmit quickly
  • Purkinje fibers spread signal to ventricles
• What do the pingi fibers stimulate in the heart?

  Cardiac muscle and ventricles to contract
• What does an ECG measure?

  Electrical activity happening in the heart
• What are the three regions of an ECG?

  P-wave, QRS complex, T-wave
• What does the P-wave correspond to?

  Depolarization of the atria
• What is the PR interval?

  Time from the beginning of P to R
• What happens during the PR interval?

  Atria contract and send blood to ventricles
• What is the difference between the PR interval and the PR segment?

  PR interval includes P to R; PR segment is P to R
• What does the QRS complex represent?

  Depolarization of the ventricles
• Why is the R spike in the QRS complex so large?

  More electrical activity in the ventricles
• What happens during the QRS complex?

  Ventricles depolarize and atria repolarize
• What is the ST interval?

  Time from S to the end of T-wave
• What occurs during the ST interval?

  Ventricles contract and pump blood
• What sound is associated with the first heart sound (S1)?

  Closure of tricuspid and mitral valves
• What does the T-wave represent?

  Repolarization of the ventricles
• What causes the second heart sound (S2)?

  Closure of aortic and pulmonary valves
• What is the sequence of the cardiac conduction pathway?

  1. SA node initiates signal
  2. Interatrial pathway depolarizes left atrium
  3. Internal pathway depolarizes right atrium
  4. AV node delays signal
  5. Bundle of His separates into left and right branches
  6. Signal passes through bundle branches and Purkinje fibers
  7. Ventricles contract
• What happens during the cardiac cycle as shown in an ECG?

  • P-wave: Atria depolarize
  • PR interval: Atria contract
  • QRS complex: Ventricles depolarize, atria repolarize
  • ST interval: Ventricles contract
  • T-wave: Ventricles repolarize
• What are the heart sounds associated with the cardiac cycle?

  • S1: Closure of tricuspid and mitral valves
  • S2: Closure of aortic and pulmonary valves
• How does the electrical conduction system ensure coordinated heart contractions?

  Signals travel quickly through pathways
• How does the contraction of the ventricles differ from that of the atria?

  Ventricles contract forcefully to pump blood far
• What happens if the AV node fails to delay the signal?

  Atria and ventricles contract simultaneously
• What is the role of the Purkinje fibers?

  Distribute signals throughout the ventricles
• Why is it important for the ventricles to contract as a unit?

  To pump blood efficiently to the body
• What is the primary function of the heart?

  Pumping blood throughout the body