Understanding Respiratory Quotient and Aerobic Respiration | Testbook.com

We all know respiration as the process of breathing in and out. However, it has another dimension that we will explore in this article. Let's dive into the concept of respiratory quotient and its relation to aerobic respiration.

Learn more: Respiration

Aerobic respiration is a common process in many organisms to efficiently use energy from food. In aerobic respiration , oxygen is consumed, and carbon dioxide is released.

The ratio of the volume of carbon dioxide eliminated to the volume of oxygen consumed during cellular respiration is known as the respiratory quotient, or RQ.

The respiratory quotient can be represented as:

The RQ depends on the type of respiratory substrate used during respiration. It is also used in calculations of the basal metabolic rate (BMR) when estimated from carbon dioxide production. These measurements are forms of indirect calorimetry.

For instance, when carbohydrates are fully oxidized, the RQ becomes one, meaning equal amounts of carbon dioxide and oxygen are evolved and consumed, respectively.

On the other hand, fat molecules are not fully oxidized during respiration, resulting in an RQ lower than 1.

When proteins serve as respiratory substrates, the RQ is about 0.9. However, in living organisms, the RQ is rarely one and is often more than one. Pure proteins and fats are seldom used as respiratory substrates.

The respiratory quotient has several applications, particularly in the medical field. For instance, it can be used in severe cases of chronic obstructive pulmonary disease. Other applications include:

• As an indicator of overfeeding or underfeeding.
• To analyze liver function.
• To predict weight gain in patients with non-insulin-dependent diabetes.
• To diagnose conditions in patients with liver cirrhosis and non-protein respiratory quotient.

Also Read: Disorders of the Respiratory System

Learn more about Respiration, Respiratory Quotient, Aerobic Respiration, and other related topics.