Circ. System pg. 40-48

• Sinoatrial node (SA node)


  Embedded nerve fibers in the wall of the right atrium that initiate heart muscle contraction
• Heart muscle contraction


  1. Stimulation of SA node

  2. Electrical signal from SA node stimulates contraction of atria
• Electrocardiogram (ECG)


  Electrical machine that can observe the electrical activity of the heart
• Electrocardiogram (ECG)


  • Generates a graph of the heart's electrical activity
• Atrial systole


  Contraction of the atria
• Diastolic blood pressure


  Blood pressure reading when the atria relax and blood moves through the AV valves into the ventricles
• P wave


  Sound of the AV valves closing after atrial contraction
• Electrical signal conduction


  AV node conducts signals to Bundle of His and Purkinje Fibers in ventricle walls
• QRS complex


  Electrical activation of the ventricles
• PR interval


  Time between atrial and ventricular activation
• QT interval


  Time between ventricular activation and recovery
• The Bundle of His is named after the discoverer, Swiss cardiologist, Wilhelm His Jr in 1893
• Ventricular contraction


  1. Simultaneous contraction of right and left ventricles

  2. Pushes blood through semilunar valves
• Systolic blood pressure


  Blood pressure reading during ventricular contraction
• T wave


  Ventricular relaxation and recovery
• Semilunar valve closure


  Causes the 'dubb' sound of the heart