What is the respiratory quotient (RQ)? What is a typical RQ value for an American diet?

Name: Problem 4, Chapter 22: Human Physiology An Integrated Approach
Uploaded: 2020-11-02T21:15:24-08:00
Duration: 4 min 41 s
Channel: Caroline Basil
Description: What is the respiratory quotient (RQ)? What is a typical RQ value for an American diet?

What is the respiratory quotient (RQ)? What is a typical RQ...

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Key Concepts

Respiratory Quotient (RQ)

The Respiratory Quotient is a dimensionless number that represents the ratio of carbon dioxide produced to oxygen consumed by an organism during metabolism. It provides insight into which type of nutrient—carbohydrate, fat, or protein—is predominantly being oxidized, with typical RQ values varying from about 0.7 for fats to around 1.0 for carbohydrates.

Dietary Influence on RQ

The macronutrient composition of a diet directly affects the RQ value. Diets that are high in carbohydrates tend to yield higher RQ values, while diets with a greater proportion of fats result in lower RQ values. A typical diet in many Western or American contexts, which often includes a substantial proportion of carbohydrates, generally leads to an RQ around 0.8 to 0.85.

Transcript

00:01 We're going to compare the respiratory quotient between glucose and tripomyotoglycerol.

00:09 So these substances are different.

00:12 So let's write out our substances here.

00:16 So we have glucose, which is six carbons, 12 hydrogens, and six oxygens, c6 h12 .106.

00:25 And for the tripomiodoglycerol, we're going to have a little bit of a different molecular formula here.

00:30 We have c -51, h -98, h -98 -o2.

00:40 So in order to compare the respiratory quotients here, we need to be able to look at the entire respiration, cellular respiration reaction for each of these molecules here.

00:53 So recall that the reaction for cellular respiration here is pretty simple.

00:59 You just have your carbohydrate, usually clearest.

01:03 Or whatever you're going to use, fructose, that kind of thing.

01:07 And then plus your oxygen here, your oxygen gas, and that will yield carbon dioxide and water.

01:20 So let's write that in here as well.

01:22 O2 yields co2 and water.

01:28 Awesome.

01:29 So let's go ahead and balance these equations so we can compare them.

01:33 So we're going to have, we're going to have six crazy pen, we're going to have six oxygens, six co2s, and six h2os for our glucose.

01:46 And for our tripe myoto glycerol, we are going to have 72 .5 oxygens...