External Nose: The external nose is composed of cartilage and bone, covered by skin, and includes the nostrils and nasal bridge, providing a passage for airflow and supporting olfaction.
The Trachea: The trachea, or windpipe, is a rigid tube reinforced with C-shaped cartilage rings that conducts air from the larynx to the bronchi while keeping the airway open.
The Respiratory Zone: The respiratory zone includes respiratory bronchioles, alveolar ducts, and alveoli, where gas exchange occurs between air and pulmonary capillary blood.
