In this sub-unit we are going to explore the contents of:

Understandings:

• Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries
• Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles
• Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange
• Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension