Module 3: Exchange & Transport

• What are alveoli?

  Tiny air sacs that serve as the primary gaseous exchange surface.
• What is the structure of alveoli?

  They consist of a thin epithelial cell layer, collagen, and elastic fibres.
• What is the definition of breathing rate?

  The number of breaths per minute.
• What are bronchi?

  Divisions of the trachea that lead into the lungs.
• What supports the structure of bronchi?

  They are small tubes supported by incomplete rings of cartilage.
• What are bronchioles?

  Many small divisions of the bronchi.
• What is the function of smooth muscle in bronchioles?

  It restricts airflow to the lungs.
• What type of cells line the bronchioles?

  They are lined with a thin layer of ciliated epithelial cells.
• What is the role of ciliated epithelial cells?

  They waft bacteria-containing mucus up to the back of the throat.
• What is countercurrent flow?

  An adaptation for gaseous exchange in bony fish.
• How does countercurrent flow work?

  Blood in the gill filaments and water flow in opposite directions.
• What are elastic fibres in the alveoli responsible for?


  They allow the alveoli to stretch and recoil.
• What defines an effective exchange surface?

  It has a large surface area, thin layers, a good blood supply, and ventilation.
• What happens during expiration?

  The diaphragm relaxes and reverts to a dome shape.
• What occurs to thoracic pressure during expiration?

  Thoracic pressure exceeds air pressure.
• What are gill filaments?

  The main site of gaseous exchange in fish.
• What is the function of gill lamellae?

  They provide a large surface area for exchange.
• What are gills?

  The organs of gaseous exchange in fish.
• What is the role of goblet cells?

  They secrete mucus onto the trachea lining.
• What happens during inspiration?

  The diaphragm contracts and flattens.
• What is the effect of thoracic pressure during inspiration?

  Thoracic pressure falls below air pressure.
• What are internal intercostal muscles responsible for?

  They are responsible for forced exhalation.
• What is the mammalian gaseous exchange system?

  A complex system in mammals for exchanging oxygen and carbon dioxide gases.
• What is the function of the operculum in bony fish?

  It protects the gills and helps maintain a constant stream of water over them.
• What is the role of smooth muscle in the trachea and bronchi?

  It constricts the lumen of the bronchi, reducing airflow.
• What are spiracles?

  Small external openings for gas exchange in insects.
• What is the function of spiracle sphincters?

  They open and close the spiracles to control gas exchange.
• What is a spirometer?

  A device used to examine patterns of breathing.
• What does tidal volume refer to?


  The volume of air that moves into and out of the lungs during a normal breath.
• What is the trachea in mammals?

  The primary airway carrying air from the nasal cavity to the chest.
• What supports the trachea?

  It is supported by incomplete rings of cartilage.
• What are tracheae in insects?

  Large tubes that run from the spiracles into the insect's body.
• What is the function of tracheal fluid?

  It affects the surface area available for gaseous exchange.
• What are tracheoles?

  Divisions of the tracheae that run throughout the tissues of an insect.
• What is the role of ventilation?

  It is the movement of fresh air into the lungs and stale air out.
• What is vital capacity?

  The largest volume of air that can be breathed in after the strongest exhalation.
• What does affinity refer to in biology?

  The tendency of one substance to bind with another substance.
• What is the aorta?

  The artery that takes oxygenated blood away from the heart to the body.
• What is an arteriole?

  A type of blood vessel that connects arteries and capillaries.
• What is the structure of arteries?

  They have walls containing collagen, smooth muscle, and elastic fibres.