mammalian gas exchange system

• Where does gas exchange take place?

  in the human thorax (a collection of organs and tissues in the chest cavity)
• What role do Ciliated epithelial cells, goblet cells and mucous glands play in the mammalian gas exchange system?

  maintaining the health of the gas exchange system
• What role do Cartilage, smooth muscle, elastic fibres and squamous epithelial tissue all play in the mammalian gas exchange system?

  important structural roles in maintaining the gas exchange system
• What role does cartilage have in the mammalian gas exchange system?

  Cartilage is a strong and flexible tissue found in various places around the body.

  One place is in rings along the trachea, called tracheal rings.

  These rings help to support the trachea and ensures it stays open while allowing it to move and flex while we breathe.
• What is the trachea and what is it's role in the mammalian gaseous exchange system?

  It's a wide tube supported by C-shaped cartilage to keep the air passage open during pressure changes.

  Lined by ciliated epithelium cells which move mucus, produced by goblet cells, toward the throat to be swallowed, preventing lung infections.

  Carries air to the bronchi.
• What are the bronchi and their role in the mammalian gaseous exchange system?

  Like the trachea they're supported by rings of cartilage and are lined by ciliated epithelium cells and goblet cells.

  However they are narrower and there are 2 of them, one for each lung.

  They allow passage of air into the bronchioles.
• Ciliated epithelium?

  • Ciliated epithelium is a specialised tissue found along the trachea down to the bronchi
  • Each cell has small projections of cilia which sweep mucus, dust and bacteria upwards and away from the lungs and the epithelium itself
• What are goblet cells?

  • They are mucus-producing cells that secrete viscous mucus which traps dust, bacteria and other microorganisms and prevents them from reaching the lungs
  • The mucus is then swept along by the cilia of the ciliated epithelium upwards and is swallowed
  • The mucus and any microorganisms will then be destroyed by the acid in the stomach
  • Goblet cells can be found scattered throughout the ciliated epithelium in the trachea
• Squamous epithelium?

  • The squamous epithelium forms the structure of the alveolar wall and so is very thin and permeable for the easy diffusion of gases
  • The alveoli have a lining of thin and squamous epithelium, that allows for gas exchange
• Smooth muscle?

  • Smooth muscle can be found throughout the walls of the bronchi and bronchioles
  • It helps to regulate the flow of air into the lungs by dilating when more air is needed and constricting when less air is needed
• Elastic fibres?

  • Elastic fibres are present in all lung tissues. They are very important as they enable the lung to stretch and recoil. This ability to recoil is what makes expiration a passive process
• Capillaries?

  • Each alveolus is surrounded by an extensive network of capillaries
  • Carbon dioxide diffuses out of the capillaries and into the alveoli to be exhaled, while oxygen diffuses the other way from alveoli and into the capillaries to be carried around the body
  • These capillaries have a diameter of around 3-4µm, which is only wide enough for one red blood cell to travel through at any one time
  • This ensures that there is sufficient time and opportunity for gas exchange to occur
• What are bronchioles?

  • Bronchioles are narrow self-supporting tubes with thin walls
  • They are not usually supported by cartilage, though a few bronchioles may contain some cartilage
  • A large number of bronchioles are present in the gas exchange system
  • Bronchioles are lined with ciliated epithelium in the same way as the trachea and bronchi, though the usually do not contain any goblet cells
  • Bronchioles vary in size and structure, getting smaller as they get closer to the alveoli
• • Bronchioles vary in size and structure, getting smaller as they get closer to the alveoli
  • The larger bronchioles possess elastic fibres and smooth muscle that adjust the size of the airway to increase or decrease airflow
  • The smallest bronchioles do not have any smooth muscle but they do have elastic fibres
• What are the alveoli, what is there role?

  They are mini air sacs, lined with epithelium cells

  They are the site of gas exchange

  Walls are one cell thick, covered with a network of capillaries

  Groups of alveoli are located at the ends of the bronchioles

  A watery fluid lines the alveoli, facilitating the diffusion of gases