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##### Respiration During Exercise (1)

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**Pulmonary Ventilation (V)**The amount of air moved in or out of the lungs per minute It is the product of tidal volume (VT) and breathing frequency V= VT x f**Pulmonary Ventilation (V)**• Dead-space ventilation (VD) • Unused ventilation (like the trachea & bronchi) • Does not participate in gas exchange**Pulmonary Ventilation (V)**• Anatomical dead space conducting zone BUT • Physiological dead space caused by disease**Pulmonary Ventilation (V)**• Alveolar ventilation (VA) • Volume of inspired gas that reaches the respiratory zone**Total minute ventilation can be subdivided into dead space**ventilation & alveolar ventilation V + V = VA + VD**Pulmonary Volumes & Capacities**• They are measured by spirometry**Pulmonary Volumes & Capacities**Inspiratory Reserve Volume (IRV) • Vital Capacity (VC): • Maximum amount of air that can be expired following a maximum inspiration Tidal Volume (TV) Expiratory Reserve Volume (ERV) Residual Volume (RV)**Pulmonary Volumes & Capacities**Inspiratory Reserve Volume (IRV) • Residual Volume (RV): • Air remaining in the lungs after a maximum expiration Tidal Volume (TV) Expiratory Reserve Volume (ERV) Residual Volume (RV)**Pulmonary Volumes & Capacities**Inspiratory Reserve Volume (IRV) • Total Lung Capacity (TLC): • The sum of VC and RV Tidal Volume (TV) Expiratory Reserve Volume (ERV) Residual Volume (RV)**Partial Pressure of Gases (Dalton’s Law)**The total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently**Partial Pressure of Gases (Dalton’s Law)**• The partial pressure of oxygen (PO2) • Air is 20.93% oxygen • This is expressed as a fraction 20.93/100 = 0.2093 • The total pressure of air = 760 mmHg • So PO2 = 0.2093 x 760 = 159 mmHg**P1**P2 Diffusion of Gases Fick's Law of Diffusion The rate of gas transfer (V gas) is proportional to the tissue area (A), the diffusion coefficient of the gas (D), and the difference in the partial pressure of the gas on the two sides of the tissue (P1-P2), And inversely proportional to the thickness (T)**Diffusion of Gases**Fick's Law of Diffusion V gas = A/T x D x (P1 – P2)