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Respiratory Quotient (RQ)

It is the ratio of volume of carbon dioxide produced to the volume of oxygen consumed over a period of time in respiration.

RQ = Volume of CO2 evolved/Volume of O2 absorbed

Respiratory Quotient varies with different food utilized. Following are the values

  • For glucose it is 1. RQ = 6 CO2 / 6O2

  • For fats it is about 0.7

  • For proteins about 0.85.

Lung Volumes and Capacities (Pulmonary Air Volumes and Capacities)

Capacities are combination of two or more pulmonary volumes.

Following are important volumes and capacities

  1. Tidal Volume (TV) is the volume of air inspired or expired with each normal breath. It is about 500 ml in normal adult. It includes

    • The alveolar volume which consists of the air that reaches to the respiratory surfaces of the alveoli and takes part in gas exchange. It is composed of about 350 ml of tidal volume

    • Dead space volume is the volume of the air that does not reach the respiratory surface. It corresponds to the conducting zone of the respiratory passage… (407 more words) …

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Oxygen dissociation curve

The curve shows the relationship between percentage % saturation of Hb at various pressures of oxygen. It shows a progressive increase in the percentage saturation of the Hb as the PO2 increases.

 Knowing the oxygen dissociation curve

Knowing the Oxygen Dissociation Curve

What is the oxygen dissociation curve

The curve has a characteristic shape, the sigmoid shape (S-shaped). The steep lower part of the curve shows that small change in the pO2 leads to significant change in percentage saturation of hemoglobin. This helps in the delivery of oxygen to the tissues. Top portion of curve is flat so a considerable change in pO… (316 more words) …

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