Gas Exchange in the Lungs

• What is the name of the tube that air passes into the lungs through?

  Trachea
• What is a key feature of the trachea?

  It contains rings of cartilage
• What is the function of the cartilage in the trachea?

  To prevent the trachea from collapsing
• What do the trachea split into?

  Two smaller tubes called bronchi
• What are bronchioles?

  Smaller tubes that branch from the bronchi
• What do bronchioles end in?

  Tiny air sacs called alveoli
• What is the primary function of alveoli?

  Sites of gas exchange
• How do gases diffuse in and out of the bloodstream in the alveoli?

  Oxygen diffuses in, carbon dioxide diffuses out
• What adaptations do alveoli have for gas exchange?

  Millions of alveoli, thin walls, good blood supply
• Why is a large surface area important for alveoli?

  It increases the rate of gas exchange
• Why do alveoli have very thin walls?

  To shorten the diffusion path
• How does a good blood supply aid gas exchange in alveoli?

  It ensures a steep concentration gradient
• What happens to oxygen once it diffuses into the blood?

  It is rapidly moved to the heart to be pumped the rest of the body’s cells
• How does breathing affect the rate of diffusion?

  It brings fresh oxygen and removes carbon dioxide
• What does breathing do to concentration gradients for gases?

  It makes them higher
• What are the adaptations of the lungs for gas exchange?

  • Millions of alveoli for large surface area
  • Very thin walls for short diffusion path
  • Good blood supply for steep concentration gradient
• What is the process of gas exchange in the alveoli?

  1. Oxygen diffuses into the bloodstream
  2. Carbon dioxide diffuses out of the bloodstream