Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Describe the passage of air from the outside environment to the lungs
Explain how the lungs are protected from particulate matter

The air in the alveoli is renewed regularly, thanks to the ventilation process. Gas exchange in the lungs takes place between the blood in the capillary network surrounding the alveoli, and the air in the alveoli itself.