Final answer:
The cells and structures that defend against bacteria and foreign particles entering the lungs include the mucus escalator, type II cells, and macrophages.
Step-by-step explanation:
The cells and structures that defend against bacteria and foreign particles entering the lungs include the mucus escalator, type II cells, and macrophages.
The mucus escalator is a mechanism in the respiratory system that moves mucus and trapped particles out of the lungs. Goblet cells secrete mucus, which helps trap particles and pathogens.
Type II cells in the alveolar wall secrete pulmonary surfactant, which reduces surface tension and helps protect the lungs. Macrophages are phagocytic cells that remove debris and pathogens from the alveoli.