Organisation

• What is the primary function of the lungs in the circulatory system?


  Gas exchange
• How does blood collect oxygen in the lungs?


  The heart pumps blood to the lungs where it collects oxygen
• What is the name of the tube through which air passes into the lungs?

  Trachea
• What is the function of the cartilage in the trachea?


  It prevents the trachea from collapsing when we inhale
• What do the trachea split into?


  Two smaller tubes called bronchi
• What are the tiny air sacs at the end of bronchioles called?


  Alveoli
• What is the role of alveoli in the lungs?

  They are the sites of gas exchange
• What happens to oxygen in the alveoli?

  It diffuses into the bloodstream
• What happens to carbon dioxide in the alveoli?


  It diffuses out of the bloodstream back into the air
• What are the adaptations of alveoli for gas exchange?


  • Millions of alveoli provide a huge surface area
  • Very thin walls create a short diffusion path
  • Good blood supply ensures rapid removal of oxygen
• Why is a good blood supply important for alveoli?


  It ensures that oxygen is rapidly removed, maintaining a steep concentration gradient
• How does breathing affect the rate of diffusion in the lungs?


  It brings fresh oxygen into the alveoli and removes carbon dioxide, increasing concentration gradients
• What should students remember about the adaptations of the lungs?


  There will be plenty of questions on the adaptations in revision workbooks
• What is the overall process of gas exchange in the lungs?


  1. Air enters the lungs through the trachea
  2. Oxygen diffuses into the bloodstream from the alveoli
  3. Carbon dioxide diffuses from the blood into the alveoli
  4. Breathing maintains concentration gradients for efficient gas exchange