B2.7 Lung 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
• How many alveoli do adults have approximately?

  Hundreds of millions
• What is the significance of the large surface area of alveoli?

  It increases the rate of gas exchange
• Why are 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 is carbon dioxide transported in the blood?

  It is dissolved in the blood plasma
• What happens to blood during gas exchange in the lungs?

  Deoxygenated blood enters and oxygenated blood leaves
• Which organ system are the lungs part of?

  Respiratory system
• How can 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
• What happens to breathing rate during exercise?

  • Breathing rate increases
  • More oxygen is needed for energy
• B

  
• D

  
• C

  
• Which structures connect the bronchi to the alveoli?

  Bronchioles
• What are the tiny air sacs in the lungs called?

  Alveoli
• What is the name of the process by which oxygen moves through the wall of the alveoli, into the blood?

  Diffusion
• How are alveoli adapted for efficient gas exchange?

  • Their walls are only one cell thick which provides a short distance for diffusion
  • There are many of them giving a large total surface area 
  • They are moist, which allows the gases to dissolve, and therefore diffuse more easily 
• Which gas diffuses from the blood in the capillaries, into the air in the alveoli?

  Carbon dioxide 
• Oxygen passes down its concentration gradient from the alveoli, into the bloodstream. 
• Which substance inside red blood cells does oxygen bind to?

  Haemoglobin 
• True or false? Carbon dioxide is transported around the body dissolved in the blood plasma. 

  True