Cardiovascular system

• Heart valves


  Ensure the unidirectional flow of blood through the heart
• Cardiac cycle


  1. Electrical impulses

  2. Muscle contractions

  3. Pressure changes

  4. Blood flow in one direction
• Cardiac output (CO)


  Volume of blood pumped out per ventricle per minute
• Factors affecting CO


  • Heart rate (HR)
  • Stroke volume (SV)
• Stroke volume (SV)


  • Volume of blood pumped out by one ventricle with each beat
  • Indicates the force of ventricular contraction
  • Difference between end diastolic volume (EDV) and end systolic volume (ESV)
• Factors affecting SV


  • Preload (degree of stretch of heart muscle)
  • Contractility (contractile strength)
  • Afterload (back pressure exerted by arterial blood)
• Regulation of heart rate

  1. Autonomic nervous system (sympathetic and parasympathetic)

  2. Chemical regulation (hormones and ions)

  3. Other factors (age, gender, exercise, body temperature)
• Coronary arteries branch from aorta just beyond aortic valve
• Most arteriole flow occurs during diastole
• Blood flow normally adjusted to meet oxygen requirements
• Cardiovascular disease (CVD)


  Diseases involving the heart or blood vessels, including coronary artery diseases such as angina and myocardial infarction
• Angina


  • Pain resulting when coronary arteries cannot deliver enough oxygen-containing blood to the heart muscle, particularly at times of higher demand
• Myocardial infarction (MI)


  • Occurs if a blood clot blocks a coronary artery
• Stroke


  • Occurs if the blood supply to part of the brain is cut off
• CVD is the most common cause of death in the UK
• CVD occurs due to atherosclerosis - a gradual build-up of fatty material within the coronary artery walls