Human Gas Exchange

• Where does gas exchange take place in humans?

  In the human thorax
• What is the thorax composed of?

  A collection of organs and tissues
• What types of tissues are present in the mammalian gas exchange system?

  Different tissue types
• How are tissues in the gas exchange system adapted?

  Each is adapted for a specific purpose
• What roles do ciliated epithelial cells, goblet cells, and mucous glands play?

  Maintain health of the gas exchange system
• What structural roles do cartilage, smooth muscle, elastic fibres, and squamous epithelial tissue have?

  Maintain the gas exchange system
• What is cartilage?

  A strong and flexible tissue
• Where is cartilage found in the body?

  In various places, including trachea
• What do tracheal rings do?

  Support the trachea and keep it open
• How do tracheal rings assist breathing?

  Allow movement and flexing while breathing
• Where is ciliated epithelium found?

  Along the trachea down to the bronchi
• What do cilia do in ciliated epithelium?

  Sweep mucus, dust, and bacteria upwards
• What are goblet cells?

  Mucus-producing cells in the trachea
• What is the function of mucus produced by goblet cells?

  Traps dust, bacteria, and microorganisms
• What happens to mucus after it traps microorganisms?

  It is swept upwards and swallowed
• How is mucus destroyed after swallowing?

  By acid in the stomach
• What type of epithelium lines the alveoli?

  Thin squamous epithelium
• Why is squamous epithelium important for the alveoli?

  Allows for easy diffusion of gases
• Where is smooth muscle found in the gas exchange system?

  In the walls of bronchi and bronchioles
• What does smooth muscle do in the gas exchange system?

  Regulates airflow into the lungs
• What is the role of elastic fibres in lung tissues?

  Enable lung to stretch and recoil
• Why is the ability to recoil important for expiration?

  It makes expiration a passive process
• What surrounds each alveolus?

  An extensive network of capillaries
• What happens to carbon dioxide in the capillaries?

  Diffuses into the alveoli to be exhaled
• What happens to oxygen in the alveoli?

  Diffuses into the capillaries to be carried
• What is the diameter of capillaries surrounding alveoli?

  Around 3-4 µm
• Why is the small diameter of capillaries important?

  Ensures time for gas exchange to occur
• What are the components of the gas exchange system?

  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
• What is the function of the trachea?

  Allows air to travel to the lungs
• What ensures the trachea remains open?

  C-shaped rings of cartilage
• Why are tracheal rings C-shaped?

  To prevent friction with the oesophagus
• What lines the trachea?

  Ciliated epithelium
• What is the function of mucus in the trachea?

  Traps dust and bacteria
• What is the structure of bronchi compared to the trachea?

  Thinner walls and smaller diameter
• How does the cartilage in bronchi differ from that in the trachea?

  Forms full rings and irregular blocks
• What are bronchioles?

  Narrow self-supporting tubes with thin walls
• What do bronchioles lack?

  Usually do not contain goblet cells
• What happens to bronchioles as they get closer to the alveoli?

  They get smaller in size and structure
• What do larger bronchioles possess?

  Elastic fibres and smooth muscle
• What do the smallest bronchioles have?

  Elastic fibres but no smooth muscle