Study Question Five

• Q5. Trace the movement of air through the conducting zones of the respiratory system to the respiratory zone. Be able to distinguish between the anatomical structures that are in the conducting zone vs. the respiratory zone.
• The conducting zone functions primarily to conduct air into the lungs. It also serves to filter, warm, and humidify the incoming air. It does not participate in gas exchange.
• Anatomical Structures in the Conducting Zone

  • nasal cavity
  • pharynx
  • larynx
  • trachea
  • bronchi
  • bronchioles
  • terminal bronchioles
• Anatomical Structures in the Conducting Zone

  • Nasal cavity: Air enters respiratory system through nostrils (nares), where it is filtered by the mucous membranes and cilia, which trap dust, debris, and pathogens.
• Anatomical Structures in the Conducting Zone

  • Pharynx: Air moves from the nasal cavity into the pharynx (throat). Pharynx is a passageway for both air and food, but air moves through nasopharynx, oropharynx, and laryngopharynx.
• Anatomical Structures in the Conducting Zone

  • Larynx: Air then passes through larynx (voice box), responsible for producing sound and also acts as a passage for air. The larynx is protected by the epiglottis, a flap that prevents food from entering the trachea.
• Anatomical Structures in the Conducting Zone

  • Trachea: After the larynx, air travels into the trachea, a rigid tube lined with cilia and mucus that further helps to filter and moisten the air. The trachea splits into the left and right main bronchi at the carina.
• Anatomical Structures in the Conducting Zone

  • Bronchi: Trachea divides into primary bronchi, each leading to one lung. Bronchi further divide into secondary (lobar) bronchi and then into tertiary (segmental) bronchi, which continue to branch smaller and smaller.
• Anatomical Structures in the Conducting Zone

  • Bronchioles: Bronchi eventually divide into smaller bronchioles. Do not have cartilage in their walls. Bronchioles are lined with smooth muscle, allowing for some regulation of airflow.
• Anatomical Structures in the Conducting Zone

  • Terminal bronchioles: Smallest bronchioles and are the last structures in the conducting zone. They lead to the respiratory bronchioles of the respiratory zone.
• The respiratory zone is where gas exchange takes place. It includes the alveoli, tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged between the air and the blood.
• Anatomical Structures in the Respiratory Zone:

  • respiratory bronchioles
  • alveolar ducts
  • alveolar sacs
  • alveoli
• Anatomical Structures in the Respiratory Zone:

  • Respiratory bronchioles: First structures in respiratory zone. Have some alveoli in their walls for limited gas exchange, but they are still mostly involved in conducting air.
• Anatomical Structures in the Respiratory Zone:

  • Alveolar ducts: Respiratory bronchioles lead into these, which are passageways that direct air to the alveolar sacs.
• Anatomical Structures in the Respiratory Zone:

  • Alveolar sacs: Clusters of alveoli at the end of the alveolar ducts. Alveoli are the primary site for gas exchange. They are lined with a thin membrane and have a rich network of capillaries surrounding them, allowing for efficient oxygen and carbon dioxide exchange between the air and the bloodstream.
• Anatomical Structures in the Respiratory Zone:

  • Alveoli: Tiny, balloon-like structures are where the actual gas exchange takes place. Have extremely thin walls and are surrounded by capillaries. Oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood to be exhaled.
• Pathway

  • Nasal cavity
  • Pharynx (nasopharynx, oropharynx, laryngopharynx)
  • Larynx
  • Trachea
  • Primary bronchi (left and right)
  • Secondary (lobar) bronchi
  • Tertiary (segmental) bronchi
  • Bronchioles
  • Terminal bronchioles (end of conducting zone)
  • Respiratory bronchioles (start of respiratory zone)
  • Alveolar ducts
  • Alveolar sacs
  • Alveoli (site of gas exchange)
• Differences

  • Conducting Zone: No gas exchange occurs, instead air is conducted and conditioned (filtered, warmed, humidified). Structures include the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles up to terminal bronchioles.
  • Respiratory Zone: Gas exchange occurs. Structures includes respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli.
• Trace movement of air through conducting zones and respiratory zone. Distinguish between the anatomical structures that are in the conducting zone vs. the respiratory zone.

  The movement of air starts at the nasal cavity, then to the pharynx, larynx, trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles. This is the conducting zone, there is not gas exchange here but air is conditioned. The next part is the respiratory zone, including respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli. Here is where gas exchange actually occurs.