Respiratory

• Pleural fluid


  Liquid located between the pleural membranes
• Pleural membrane


  Two-layer membrane that covers the lungs and lines the chest cavity
• Function of pleural fluid


  • Keeps the pleural membranes moist
  • Reduces friction between the membranes when you breathe
• Air entry


  1. Enters through the nasal cavity

  2. Warmed and filtered

  3. Continues into the lungs and other parts of the respiratory system
• Function of the respiratory system

  • Provide the tissues with oxygen
  • Remove carbon dioxide to facilitate the process of respiration
• Respiratory surfaces


  Parts of the body where gas exchange takes place between the atmosphere and the blood
• Respiratory surfaces in humans

  • Gas exchange takes place in the alveoli
  • Oxygen diffuses into the blood
  • Carbon dioxide diffuses from the blood into the alveoli
• Adaptations of respiratory surfaces in humans


  • Many alveoli with large surface area
  • Thin walls with only two layers of cells
  • Moist walls
  • Permeable membranes
  • Good blood supply
  • Ventilation
• Ventilation


  The process of breathing that ensures a high diffusion gradient to encourage oxygen into the blood and carbon dioxide from the blood
• Respiratory surfaces in plants

  The spongy mesophyll cells surrounding air spaces in the leaf
• Adaptations of respiratory surfaces in plants

  • Large surface area from many cells in contact with the airspace
  • Thin, moist and permeable cell membranes