Ventilation–perfusion coupling

Ventilation–perfusion coupling is the relationship between ventilation and perfusion in the respiratory and cardiovascular systems. Ventilation is the movement of air in and out of the lungs during breathing. Perfusion is the process of pulmonary blood circulation, which reoxygenates blood, allowing it to transport oxygen to body tissues. Lung structure, alveolar organization, and alveolar capillaries contribute to the physiological mechanism of ventilation and perfusion.

Ventilation–perfusion coupling maintains a constant ventilation/perfusion ratio near 0.8 on average, with regional variation within the lungs due to gravity. When the ratio gets above or below 0.8, it is considered abnormal ventilation-perfusion coupling, also known as a ventilation–perfusion mismatch. Lung diseases, cardiac shunts, and smoking can cause a ventilation–perfusion mismatch that results in significant symptoms and diseases; treatments include bronchodilators and oxygen therapy.

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