Lec # 4. Physiology for doctor of physical therapy

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1. Diffusion of gases across the alveolar membrane

2. Relationship between ventilation and perfusion Gas exchange occurs in the lungs between alveolar air and the blood of the pulmonary capillaries. For effective gas exchange to occur, alveoli must be ventilated and perfused. Ventilation (V) refers to the flow of air into and out of the alveoli, while perfusion (Q) refers to the flow of blood to alveolar capillaries. Individual alveoli have variable degrees of ventilation and perfusion in different regions of the lungs. Collective changes in ventilation and perfusion in the lungs are measured clinically using the ratio of ventilation to perfusion (V/Q)

3. VENTILATION-PERFUSION RATIO Ventilation perfusion ratio is the ratio of alveolar ventilation and the amount of blood that perfuse the alveoli . It is expressed as VA/Q. VA is alveolar ventilation and Q is the blood flow (perfusion). „Normal Value Normal value of ventilation ­ perfusion ratio is about 0.84.

4. Mechanism of transport of oxygen and carbon dioxide in blood

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