Gas Exchange in Animals

• Why is gas exchange considered a universal function?

  All organisms, including aquatic ones, perform it
• What are type 1 pneumocytes part of?

  Structure of lungs called alveoli
• What is a key characteristic of gas exchange surfaces?

  They are very thin to decrease diffusion distance
• Why do gas exchange surfaces need to be moist?

  Gases diffuse better when dissolved in solution
• How does diffusion occur in gas exchange?

  It is the passive movement from high to low concentration
• What drives the diffusion process in unicellular organisms?

  Low oxygen concentration due to consumption
• What is the role of ventilation in gas exchange?

  It moves air or water to drive diffusion
• What are the main components of mammalian lungs for gas exchange?

  • Mouth connects to trachea
  • Trachea splits into bronchi
  • Bronchi split into bronchioles
  • Bronchioles end in alveoli
• What is the singular form of bronchi?

  Bronchus
• What is the function of type 2 pneumocytes?

  They produce surfactant to reduce surface tension
• What is surfactant's role in the alveoli?

  It prevents alveoli from collapsing
• How does the diaphragm contribute to inhalation?

  It contracts and flattens to increase chest volume
• What happens during exhalation?

  Diaphragm relaxes, increasing chest pressure
• What is vital capacity in lung volumes?

  • Total maximum air lungs can hold
  • Includes tidal volume, inspiratory reserve, and expiratory reserve
• What is tidal volume?

  Volume of air inhaled or exhaled in each breath
• What is inspiratory reserve volume (IRV)?

  Air that can be inhaled after a normal breath
• What is expiratory reserve volume (ERV)?

  Air that can be exhaled after a normal breath
• What is the purpose of a spirometer?

  To measure lung volumes during breathing
• How can lung volumes be measured without a spirometer?

  Using a bell jar filled with water
• What happens to water level in a bell jar during exhalation?

  • Air bubbles rise in water
  • Water level decreases as air is exhaled