human circulatory system

• origin of heart is

  mesodermal
• number of action potentials that can be generated by the SAN

  70-75 per minute
• the volume of blood pumped out by each ventricle is called

  stroke volume
• cardiac output can be defined as

  the amount of blood pumped by each ventricle per minute
• cardiac output =

  stroke volume x heart rate
• value of cardiac output

  5 L/min
• end systolic volume is

  the amount of blood remaining in the heart
• duration of cardiac cycle is

  0.8 s
• duration of atrial systole and atrial diastole respectively is

  0.1 s and 0.7 s
• duration of ventricular systole and ventricular diastole respectively is

  0.5 s and 0.3 s
• lub sound is associated with the closure of

  atrioventricular valves
• dull and prolonged sound is of

  lub
• lub is produced at

  start of ventricular systole
• dub sound is associated with the closure of

  semilunar valves
• sharp, short and high pitched sound is of

  dub
• dub sound is produced at

  start of ventricular diastole
• P wave represents

  depolarisation of atria
• QRS complex represents

  depolarisation of ventricles
• T wave represents

  repolarisation of ventricles
• electrolytic activity is represented by

  T wave
• enlarged P wave represents

  enlarged atria
• enlarged Q wave represents

  myocardial infarction
• enlarged R wave represents

  enlarged ventricles
• enlarged T wave represents

  high K+
• flat T wave represents

  Hypoxia (ischemic heart disease)
• reduced flat wave represents

  coronary ischemia
• tunica intima is a

  internal lining of squamous endothelium
• tunica media is the middle layer consisting

  layer of circular smooth muscles and elastic fibres
• tunica externa is an external layer of

  fibrous CT with collagen fibres, elastin and longitudinal smooth muscles