Lungs and gas exchange

• What is the primary function of the lungs?

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

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

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

  It divides between the two bronchi
• What are the small sacks in the lungs called?

  Alveoli
• How are alveoli adapted for gas exchange?

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

  It creates a short diffusion pathway
• 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 for diffusion
• What is the concentration gradient for oxygen in the alveoli?

  Higher in alveoli than in blood
• How is carbon dioxide transported in the blood?

  It is dissolved in the blood plasma
• What happens to deoxygenated blood in the lungs?

  It enters the capillaries for oxygenation
• What changes occur in breathing rate during exercise?

  Breathing rate increases
• How do you calculate breathing rate?

  Divide breaths taken by time in minutes
• If you took 42 breaths in three 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
• Describe 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