Gas exchange & lungs

• 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?

  The 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 large surface area and thin walls
• How does the structure of alveoli facilitate diffusion?

  Thin walls create 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 alveolar walls moist?

  To allow gases to dissolve for diffusion
• What happens to hemoglobin in red blood cells in the lungs?

  It gives up oxygen to the tissues
• What is the concentration gradient for oxygen in the alveoli?

  Higher in the alveoli than in the blood
• How does carbon dioxide move in the lungs?

  It diffuses from blood to alveoli
• How is carbon dioxide carried in the blood?

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

  Gas exchange occurs all the time
• What changes in breathing rate occur during exercise?

  Breathing rate increases to meet demand
• 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
  • Short diffusion pathway
• 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
• What happens to the blood during the gas exchange process?

  • Deoxygenated blood enters capillaries
  • Oxygenated blood leaves capillaries
  • Continuous cycle of gas exchange
• What factors affect breathing rate during physical activity?

  • Increased oxygen demand
  • Increased carbon dioxide production
  • Body's need to maintain homeostasis