Respiratory system

Respiratory system

• Performs the function of external respiration — gas exchange between the external and internal environment of the body.
• Is also involved in providing a number of non-respiratory functions (blood deposition, thermoregulation, coagulogenesis, electrolyte and water balance and lipid metabolism, endocrine, immune).
• Includes: nasal cavity with paranasal sinuses, nasopharynx, larynx, trachea, main bronchi and lungs.
• Structurally and functionally is divided into airways and respiratory portion.

Airways

• Are formed by a complex of hollow tubular organs connecting the external environment with the respiratory portion of the lungs.
• Provide conduction, warming, humidification and purification of inhaled air; participate in the processes of voice formation and chemoreception.
• Are divided into extrapulmonary and intrapulmonary.

Wall of the airways is formed by mucous membrane, submucosa, fibrous cartilaginous layer and adventitia. Along the course of the extrapulmonary and intrapulmonary airways, the degree of development and the tissue composition of these membranes undergo regular changes.

The inner surface of the airways is lined with respiratory (ingle-layered multi-row ciliated) epithelium, which together with secretory elements of the wall of organs forms mucociliary transport system, providing purification of the mucous membrane from dust particles and microorganisms settling on it.

Respiratory epithelium of the airways

Mucociliary tracheal transport system

Respiratory portion

• Form the parenchyma of the lung.
• Provide gas exchange between the blood flowing through the capillaries of the lung and the air in the cavity of the pulmonary alveoli.