Circulatory System

• components of the circulatory system

  • heart
  • veins
  • arteries
  • capillaries
  • red blood cells - erthocytes
  • white blood cells - leukocytes
  • platelets - thrombocytes
  • plasma
• erythrocytes (red blood cells)

  • contains iron (red colour)
  • contains protein haemoglobin (carries oxygen to cells and carbon dioxide to lungs)
  • produced in bone marrow
• leukocytes (white blood cells)

  • protects the body from invading bacteria/harmful substances
  • helps the body to fight off infections and diseases
  • fewer WBC to RBC
• thrombocytes (platelets)

  • type of WBC to aid blood clotting of a damages vessel
• plasma

  • carry nutrients, hormones and proteins around the body
  • remove waste from the body
• what are the functions of the blood?


  • transportation - oxygen, nutrients and hormones
  • regulation - pH, temperature and water content
  • protection - clotting and white blood cells
• what are the different blood vessels?


  • areteries
  • veins
  • capillaries
• arteries

  • transports oxygen rich blood from heart - except the pulmonary artery (carries deoxygenated blood to lungs)
  • blood is at high pressure - thick muscular walls - tunica intime (inner layer), tunica media (middle layer) and tunica externa (outer layer)
  • elastic fibers and smooth muscle to the arteries can expand and contract
• veins

  • transports deoxygenated blood from the body back to heart - except the pulmanory veins which carry oxygenated blood from the lungs to the heart
  • thinner walls, less smooth muscle and elastic fibres
  • contains valves - prevents backflow of blood
  • lumen is larger than arteries to hold a larger volume of blood
• capillaries

  • easy exchange of gas, nutrients and waste products
  • narrow lumen (wide enough for red blood cells in single file)
  • walls are one cell thick
  • site of exchange between tissues
  • connects arterioles (small arteries) to venules (small veins) for efficient exchange of substances
• what are the components of the heart


  • superior vena cava
  • pulmonary artery
  • pulmonary vein
  • right atrium
  • tricuspid valve
  • right ventricle
  • inferior vena cava
  • aorta
  • pulmonary artery
  • pulmonary vein
  • left atrium
  • mitral valve
  • left ventricle
  • septum
• chambers of the heart

  • right atrium - receives deoxygenated blood from body through vena cava. During heatbeat it contracts pushing blood to right ventricle
  • right ventricle - receives blood from right atrium + pumps it to lungs via pulmonary artery. Contraction causes blood to be pushed through the pulmonary valve into pulmonary artery
  • left atrium - receives oxygenated blood from lungs through pulmonary veins. Contraction causes oxygen-rich blood to be pushes into left ventricle
  • left ventricle - receives blood from left atrium + pumps to body through aorta. Has thick muscular walls
• valves of the heart

  • bicuspid valve (mitral valve) - located between left atrium and ventricle
  • tricuspid valve - located between right atrium and ventricle
  • chordae tendineae - tough fibrous cords attatched to bicuspid and tricuspid valves, connecting flaps to the papillary muscles in the ventricles and preventing the valves from inverting