hengitysvirrat

Hengitysvirrat, or breathing currents, describe the movement of air through the respiratory tract during breathing. In physiology the term refers to the pattern and rate of air flow between the atmosphere and the lungs as driven by pressure differences. The concept is also used in building engineering to refer to controlled indoor air movement created by ventilation systems.

In the human respiratory system, inspiration occurs when respiratory muscles contract, enlarging the thoracic cavity and making intrapleural pressure more negative. Alveolar pressure falls below atmospheric pressure, drawing air into the lungs. Expiration is typically passive, driven by elastic recoil, with air leaving as alveolar pressure rises above atmospheric pressure; during forced breathing expiratory muscles contribute. Key descriptors include tidal volume, minute ventilation, and flow measures such as the flow-volume loop, FEV1 and FVC. Airflow tends to be laminar in small airways and can be turbulent in larger airways; airway resistance and lung compliance shape the overall hengitysvirrats. Surfactant lowers surface tension and facilitates ease of flow.

Clinical relevance: Disturbed hengitysvirrat are characteristic of respiratory diseases. Asthma and COPD increase airway resistance and alter expiratory flow, while restrictive diseases reduce lung volumes. Spirometry can reveal reduced FEV1, FVC, or abnormal flow-volume patterns, guiding diagnosis and management.

Environmental context: The term also describes air movement in buildings, influenced by ventilation design, temperature differences, and opening configurations. Adequate hengitysvirrat are essential for indoor air quality and comfort, and are assessed using airflow measurements and tracer-gas methods.