Gas Exchange and Lungs

• What is the primary function of the lungs?


  To get oxygen from the air into the bloodstream
• Why do all cells need oxygen?


  For the process of cellular respiration to produce energy
• What is the trachea also known as?


  The windpipe
• What happens to air after it passes through the trachea?


  It divides between the two bronchi and further into bronchioles
• What are the small sacks in the lungs called?

  Alveoli
• How are alveoli adapted for gas exchange?


  They have a thin cell layer and a large surface area
• Why does the thin cell layer of alveoli increase the rate of diffusion?


  It creates a short diffusion pathway for gases
• How many alveoli do adults have approximately?


  Hundreds of millions
• What would happen if all alveoli were spread out flat?


  They would cover half a tennis court
• Why are the walls of alveoli moist?


  To allow gases to dissolve and increase diffusion rate
• How is carbon dioxide transported in the blood?


  It is dissolved in the blood plasma
• What is the concentration gradient for oxygen in the alveoli?


  Higher in the alveoli than in the blood
• What happens to carbon dioxide during gas exchange?


  It diffuses from the blood into the alveoli
• What happens to the blood during gas exchange?

  Deoxygenated blood enters the capillaries and oxygenated blood leaves
• How does exercise affect breathing rate?


  It increases the breathing rate
• How do you calculate breathing rate?


  Divide the number of breaths taken by the time in minutes
• If you took 42 breaths in 3 minutes, what is your breathing rate?


  14 breaths per minute
• What are the key features of alveoli that facilitate gas exchange?


  • One layer of thin cells
  • Large surface area
  • Moist walls for gas dissolution
• What is the process of gas exchange in the lungs?


  1. Oxygen diffuses from alveoli to blood
  2. Carbon dioxide diffuses from blood to alveoli
  3. Oxygenated blood is transported to the body
  4. Deoxygenated blood returns to the lungs