B3.1 Gas Exchange in Animals [IB Biology SL/HL]

What is gas exchange and why is it important for organisms?

Gas exchange is the universal function for organisms involving the intake of oxygen and the release of carbon dioxide, crucial for survival.

What type of cells make up a large portion of the lungs and aid in gas exchange?

Type 1 pneumocytes are flat cells that line the alveoli and facilitate gas exchange.

What characteristics do gas exchange surfaces typically have?

Gas exchange surfaces are thin, permeable to gases, have a large surface area to volume ratio, and are often moist.

How does diffusion contribute to gas exchange?

Diffusion is the passive movement of molecules from high concentration to low concentration, driving gas exchange.

What is the role of surfactant produced by type 2 pneumocytes?

Surfactant reduces surface tension in alveoli, preventing collapse and adding moisture for better gas diffusion.

What is the function of the diaphragm during inhalation?

During inhalation, the diaphragm contracts and flattens, increasing the chest cavity volume and creating a vacuum that draws air in.

Describe the process of exhalation. What happens to the diaphragm?

During exhalation, the diaphragm relaxes and domes up, reducing the chest cavity volume and increasing pressure to force air out.

What are tidal volume, inspiratory reserve volume, and expiratory reserve volume?

Tidal volume (TV) is the air volume per breath; inspiratory reserve volume (IRV) is extra air that can be inhaled; expiratory reserve volume (ERV) is extra air that can be exhaled.

What is vital capacity?

Vital capacity is the maximum amount of air that the lungs can hold, including tidal volume, inspiratory reserve volume, and expiratory reserve volume.

What is a spirometer used for?

A spirometer measures the volume of air inhaled and exhaled, providing data on lung function.