The lungs + gas exchange

• What structure keeps the trachea open?

  Rings of cartilage
• What are the smaller branches of the bronchus called?

  Bronchioles
• Where does gas exchange take place in the lungs?

  In the alveoli
• What are the adaptations for gas exchange in the alveoli?

  • Air is ventilated, maintaining a steep concentration gradient
  • Surrounded by capillaries for good blood supply
  • Very thin walls for a short diffusion pathway
  • Large surface area to volume ratio for maximizing diffusion
• Why is a good blood supply important for gas exchange in the alveoli?

  It helps maintain a steep concentration gradient
• How do the walls of the alveoli contribute to gas exchange?

  They are very thin, providing a short diffusion pathway
• What is the significance of a large surface area to volume ratio in the alveoli?

  It maximizes diffusion
• Why do fish need an efficient gas exchange process?

  To extract oxygen from water effectively
• Where does water enter in fish for gas exchange?

  Through the gills
• Where does gas exchange occur in fish?

  In the spaces of the gill filaments
• What are the adaptations of gill filaments for gas exchange?

  • Provide a large surface area
  • Have a good blood supply with many capillaries
  • Are only two cells thick for a short diffusion pathway
  • Are ventilated to maintain a counter-current flow
• What does maintaining a counter-current flow in fish gills achieve?

  It helps maintain a steep concentration gradient
• What is the exchange of oxygen and carbon dioxide between living things and their environment called?

  Gas exchange
• What are the main structures involved in the respiratory system?

  • Trachea
  • Bronchus
  • Bronchioles
  • Alveoli
  • Diaphragm
• What are the main components of the heart?

  • Atria
  • Ventricles
  • Valves
  • Blood vessels