Circulatory system

• Main components of the Circulatory System

  • Blood
  • Blood vessels
  • Year 12 topic I
• Major functions of the Circulatory System

  • Transport
  • Defence against disease
• Red blood cells


  • Carry oxygen from the lungs to the body
  • Biconcave in shape
  • Contain haemoglobin
  • Have no nucleus
• White blood cells (WBCs)

  • Phagocytes
  • Have a lobed nucleus
  • Engulf and digest microbes
• Platelets


  • Cell fragments
  • Assist in blood clotting
  • Convert fibrinogen into fibrin
• Plasma


  The fluid part of the blood that contains water, minerals, and proteins
• Lymphocytes


  • Type of WBC
  • Have a round nucleus
  • Produce antibodies
• Red blood cell


  Becomes turgid (swollen) in a plant cell due to water entering by osmosis, and swells and bursts in an animal cell - this is called cell lysis