W1-L4: Calorimetry & Respiratory

Question 1

What is Calorimetry?

Answer 1

defines the measurement of heat transfer

2 types: direct and indirect calorimetry

Question 2

What is a Calorie?

Answer 2

Calorie (unit)
* Energy required to raise 1g of water 1 °C
* kcal =“food calorie”
* 1 kcal= 4.184 kJ

Question 3

Direct and Indirect Calorimetry

Answer 3

Question 4

What is Direct Calorimetry?

Answer 4

actual heat measurement
pipe has known amount of water and absorbs the heat produced by the person

Question 5

What is Indirect Calorimetry?

Answer 5

• All energy-releasing reactions in humans ultimately depend on oxygen use, so measuring oxygen consumption during physical activities provides an indirect yet accurate estimate of energy expenditure
• Relatively simple and inexpensive
• Yields results similar to direct measurement

Question 6

What are the 2 Types of Indirect Calorimetry?

Answer 6

1. Closed-circuit spirometry
2. Open-circuit spirometry

Question 7

Portable Open
Spirometry System

Answer 7

Question 8

1. Closed-circuit spirometry

Answer 8

Question 9

How deos Open-Circuit Spirometry work?

Answer 9

Simple and practical way to measure O2 uptake and CO2 production to infer energy expenditure

• Subject inhales ambient air with a constant composition
  (20.93% O2, 0.03% CO2 , 79.04% N2)

Question 10

Absolute - Relative

Answer 10

Relatively left has a higher VO2 max but right still has an absolute greater/

Question 11

Respiratory Quotient

Answer 11

Respiratory quotient (RQ) describes this ratio of metabolic gas exchange

provides a convenient guide to approximate nutrient mixture catabolized for energy

Question 12

Respiratory exchange ratio (RER)

Answer 12

Similar to RQ, but based off the pulmonary exchange of oxygen and carbon dioxide measured at the mouth

• Measured by gas exchange (indirect calorimetry)
• Differs from RQ during non-steady state conditions.
• seldom reflects oxidation of one macronutrient, but instead a mixture with an RQ intermediate between 0.70 and 1.00

Question 13

RQ Carbohydrate

Answer 13

Question 14

RQ for Fat

Answer 14

Question 15

Respiratory Exchange Ratio (RER), cont.

Answer 15

RER >1.00 indicates excess CO2 production in relation to O2 uptake

Question 16

What is Hyperventilation?

Answer 16

(over breathing) increases C 2 to disproportionately higher levels compared to current metabolic demands

Question 17

What is Buffering?

Answer 17

Buffering during intense exercise produces carbonic acid, which degrades to CO2 and H2O, with the lungs readily expelling CO2