Lungs

• What does oxygen enter?

  Blood capillaries in the alveoli in the lungs

  • Alveoli have a HIGHER pO2, so oxygen loads onto haemoglobin to form oxyhaemoglobin
• What do cells do when they RESPIRE??

  • They use up oxygen- this lowers the pO2
  • Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen
• What happens after red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen?

  The haemoglobin then returns to the lungs to pick up more oxygen