Cardiac cycle

• Sinoatrial node


  pacemaker of the heart
• Atrioventricular node


  node that picks up the signal of contraction from the sinoatrial node and passes the signal along to the ventricle muscle
• ECG


  electrocardiogram

  A measurement of heart electrical activity
• P wave

  atrial depolarization

  
• QRS Complex

  ventricular depolarization and atrial repolarization

  
• T wave

  ventricular repolarization

  
• systolic pressure

  first number of a blood pressure reading; measures the pressure on artery walls when heart ventricles contract
• diastolic pressure

  second number of a blood pressure reading; measurement of the pressure on artery walls when the heart is relaxed
• 120/80

  Normal blood pressure
• P wave

  Length of depolarisation to contract the Atria
• P-R Interval

  Time for the electrical signal to travel from the SA node to the AV node
• Q-T Interval


  time for signal to completely travel through the ventricles (depolarization - repolarization)
• Purkinje fibers


  carry electrical signal to the myocardium
• AV bundle


  receives signal from AV node, connection between atria and ventricles
• AV branches


  transmit signal from AV bundle, through septum, to left and right ventricle Purkinje fibers
• S-T segment


  plateau phase, ventricular systole
• P-Q segment


  plateau phase, atrial systole
• Depolarization


  Na+ channels open, trigger contraction
• Plateau


  Ca2+ channels open with K+ channels to maintain depolarization for duration of contraction
• Repolarization


  Only K+ channels are open for return to RMP (relaxation occurs)
• Systole


  contraction of a heart chamber
• Diastole


  relaxation of a heart chamber
• Blood pressure


  force per unit area exerted by the blood against the walls of blood vessels
• Systolic pressure


  arterial blood pressure during contraction of the ventricles
• Diastolic pressure


  arterial blood pressure during relaxation of the ventricles