Respiration is the rhythmic (uniform) expansion and contraction process of the pulmonary alveoli, which ensures the interaction of atmospheric air with the blood in the capillaries of the alveolar walls of the lungs. The respiratory system consists of air-conducting pathways including the nasal cavity, larynx, trachea and bronchi, as well as respiratory sections consisting of pulmonary vesicles – alveoli. In the airways, the air is humidified, warmed, and cleaned from various dust particles. In the respiratory sections, gas exchange occurs between the blood and the alveoli. In the nasal cavity, the vestibule and respiratory parts are distinguished. The vestibule is covered with stratified squamous epithelium, which is a continuation of the skin epithelium. Under the epithelium are sebaceous glands and hair roots. Many hairs located here retain dust particles from the inhaled air. The respiratory system is prone to various diseases. One of the most common diseases is bronchitis, which is characterized by inflammation of the bronchi and manifests with coughing and sputum production. Pneumonia is inflammation of the lung tissue, characterized by fever, shortness of breath and severe cough. Bronchial asthma is a chronic disease in which the bronchi narrow due to allergic or other causes, making breathing difficult.