SC F3 2.2

• The Movement and Exchange of Gases in The Human Body

  Definition

  • Oxygen and carbon dioxide gas exchange occurs in the alveoli in the lungs and is transported using red blood cells to all cells of the body
• Gas exchange in the alveoli and cells of the body

  1. High oxygen content in the alveoli causes oxygen diffusion into the blood capillaries

  2. Oxygen combines with hemoglobin to form oxyhaemoglobin in the blood capillaries

  3. Oxyhaemoglobin is transported using red blood cells to all cells of the body and oxygen is released

  4. Oxidation (cellular respiration) takes place in the cells of the body to produce energy and carbon dioxide

  5. Carbon dioxide permeates from the cells into the capillary tissue and is subsequently transported to the lungs for elimination
• The adaptation of alveolar structure to maximize gas exchange:

  • A large surface area for gas exchange in the alveoli can increase the oxygen content
  • The surface of the alveoli is moist so that gas easily permeates out and into the alveoli
  • The alveoli are thin-walled as thick as one cell to facilitate gas prescription
  • The alveoli are surrounded by a network of blood capillaries to facilitate rapid gas transport