Cardiovasucular

• Where is the human heart located?

  Just beneath the breastbone
• What is the approximate size of the human heart?

  About twice the size of a clenched fist
• What is the average weight of the human heart in females?

  250-300 g
• What is the average weight of the human heart in males?

  300-350 g
• What is the primary composition of the human heart?

  Mostly cardiac muscle (~70% of cardiac cell volume)
• How many chambers does the human heart have?

  Four separate chambers
• What is the function of the human heart?

  To pump blood around the body
• How much blood does the heart pump in a lifetime if it beats 72 bpm for a lifespan of 68.6 years?

  189,800,000 litres
• What is the blood volume pumped per minute if the heart pumps at 0.073 l/min?

  0.073 l/min
• What are the four chambers of the human heart and their functions?

  • Right atrium: Receives blood from the body
  • Right ventricle: Pumps blood to the lungs
  • Left atrium: Receives blood from the lungs
  • Left ventricle: Pumps blood to the body
• What is a ventricular septal defect?

  A gap between the left and right ventricles allowing blood to mix
• What is the prevalence of ventricular septal defects?

  ~1/500 live births
• What is coarctation of the aorta?

  A narrowing of part of the aorta that increases the workload on the left ventricle
• What is the prevalence of coarctation of the aorta?

  ~1/1500 live births
• What are the four abnormalities associated with Tetralogy of Fallot?

  1. Narrowing of the pulmonary valve

  2. Thickening of the wall of the right ventricle

  3. Displacement of the aorta over the ventricular septal defect

  4. Ventricular septal defect
• What are the four heart valves and their functions?

  • Tricuspid valve: Between right atrium and right ventricle
  • Pulmonary valve: Between right ventricle and pulmonary artery
  • Aortic valve: Between left ventricle and aorta
  • Mitral (bicuspid) valve: Between left atrium and left ventricle
• What are the atrioventricular (AV) valves and their function?

  They prevent backflow of blood between atria and ventricles
• How do semilunar valves function?


  They open when blood is pumped into arteries and close when ventricles relax
• What is the most common cardiac valvular anomaly?

  Bicuspid aortic valve
• What can a cleft mitral valve cause?

  Mitral valve stenosis
• What is aortic stenosis and what can cause it?

  Calcification of valves caused by rheumatic heart disease
• What are the effects of valve stenosis?

  • Stiff valves that do not close properly
  • Leaky valves causing backflow of blood
  • Increased workload on the heart
  • May require heart surgery
• What is the cardiac cycle?

  1. Relaxation phase (diastole)

  2. Atrial systole

  3. Ventricular systole
• How long does one complete cardiac cycle take in an adult human at rest?

  ~0.8 s
• What occurs during the relaxation phase of the cardiac cycle?

  Atria and ventricles are in diastole and blood returns to the heart
• What happens during atrial systole?

  Atria contract and force blood into the ventricles
• What occurs during ventricular systole?

  Ventricles contract and pump blood into the large arteries
• How do cardiac muscle cells contract?

  They can contract without any signal from the nervous system
• What is the role of the sinoatrial (SA) node?

  It maintains the heart's pumping rhythm by setting the contraction rate
• Where is the SA node located?

  Within the wall of the right atrium
• What happens when the SA node generates electrical impulses?

  Impulses spread through atrial walls causing them to contract
• What is the function of the atrioventricular (AV) node?

  It acts as a relay point between the right atrium and right ventricle
• Why is there a delay at the AV node?

  To ensure atria contract first and empty completely before ventricles contract
• What are Purkinje fibres responsible for?


  Conducting the signal to contract throughout the walls of the ventricle
• How is heart rate regulated?

  • SA node sets the tempo
  • Influenced by various signals and hormones
  • Body temperature affects pacemaker activity
  • Positive and negative chronotropic factors adjust heart rate
• What is an electrocardiogram (ECG)?


  A procedure that records electrical impulses during the cardiac cycle
• What does the P wave in an ECG represent?

  Impulses originating in the SA node and spreading into the atria
• What does the QRS complex in an ECG represent?


  Impulse spreading from the AV node to the ventricles
• What does the T wave in an ECG represent?

  Repolarization of the ventricle prior to the next impulse
• What happens if the SA node does not work?

  Artificial pacemakers can compensate for the heart rate