Question

What is the respiratory quotient?

Answer 1

Hint: During respiration, oxygen is taken up by the lungs, which is used to break down nutrients, and carbon dioxide is released, which is formed as the byproduct of the aforementioned breakdown.

Complete answer: The respiratory quotient is the ratio of the volume of carbon dioxide expelled to the volume of oxygen used during cellular respiration. It is also known as the respiratory ratio and is represented by RQ.
Respiratory quotient, RQ = Volume of Carbon dioxide expelled / Volume of Oxygen consumed.

Additional information:
>The respiratory quotient depends on the type of substrate used during the cellular - respiration i.e. the substrate used to breakdown and produce ATP.
>When the carbohydrates are completely broken down which are used as a substrate, the respiratory quotient is almost one.
>However, when fats are used during cellular respiration, the respiratory quotient drops to lower than one, approximately 0.7.
>When proteins tend to be involved in respiration and are respiratory substrates the ratio would be about 0.9 to 0.8.
>Also, the respiratory quotient is a unitless number utilized in the estimations of the basal metabolic rate or BMR when evaluated from the amount of carbon dioxide produced.
>These estimations are types of indirect calorimetry. It is measured using the Ganong’s respirometer.

Note: Uses of the respiratory quotient are:
-To detect severe cases of chronic obstructive pulmonary and lung disease.
-To calculate the capacity of the lung.
-As an indicator of over or underfeeding in patients.
-To analyze the functioning of the liver.
-To predict weight increase in insulin-independent diabetic patients.
-To diagnose the patient’s conditions, who have conditions like liver cirrhosis and non-protein respiratory quotients.