Epiglottis guards the front opening (glottis) of the wind pipe. It closes the wind pipe at the time of swallowing of food, and hence prevents any wrongful entry of food into the wind pipe.
Larynx contains two ligamentous folds called 'vocal cords'. Air expelled forcibly through the vocal cords vibrates them to produce sound.
Alveoli are richly supplied with blood capillaries covering their walls. The walls of the alveoli are extremely thin and moist for allowing faster diffusion of gases.
Pleura protects the lungs. The fluid filled in the space between the outer and inner pleura acts as a shock absorber for the lungs.
The lining of the nasal chamber has mucous (a sticky fluid) which traps germs and dust, so they don't enter our body.