Learning Module 3: Measuring Metabolic Rate

1
Learning Module 3Measuring Metabolic Rate
Clark J Cotton
2
Measuring Metabolic Rate

• Metabolic Rate the sum of all energetic
  processes occuring in the body.

3
Measuring Metabolic Rate

• Metabolic Rate the sum of all energetic
  processes occuring in the body.
• How do you measure metabolic rate?

4
Measuring Metabolic Rate

• Metabolic Rate the sum of all energetic
  processes occuring in the body.
• How do you measure metabolic rate?
• Direct Calorimetry

5
Measuring Metabolic Rate

• Metabolic Rate the sum of all energetic
  processes occuring in the body.
• How do you measure metabolic rate?
• Direct Calorimetry
• Mass Balance

6
Measuring Metabolic Rate

• Metabolic Rate the sum of all energetic
  processes occuring in the body.
• How do you measure metabolic rate?
• Direct Calorimetry
• Mass Balance
• Oxygen Consumption

7
Whats Oxygen Got to do with It?

• Oxygen is the basic reducing compound used to
  convert sugar to carbon dioxide, releasing energy
  for our bodies and producing carbon dioxide.
• Depending on level of activity, almost all of our
  metabolism is dependent on oxygen.

6 O2 C6H12O6
6 CO2 6 H2O
8
Measuring Metabolic Rate

• Materials 1 empty milk jug, plastic tubing,
  500ml beaker, permanent markers.
• Gradually fill up milk jug in 500ml increments,
  mark each addition.
• Flip jug upside down in tub of water and insert
  plastic tube.
• If you breath in through your nose, and out
  through your mouth you can calculate the amount
  of air you breath.

9
Tidal Volumes

• Tidal volume is the volume of air you inhale and
  then exhale with each breath.

10
Vital Capacity

• Vital Capacity is the maximum amount of air that
  you can inhale and exhale.

11
Dead Space

• Dead space volume is the volume of air that does
  not participate in gas exchange because of airway
  volume. Dead space volume (ml) body weight
  (kg) 2.2

12
Total Lung Capacity

• Total lung capacity is equal to the vital
  capacity the dead space.

13
Measuring Metabolic Rate

• If you know the number of breaths you take per
  minute, and the average volume of air per breath,
  you can calculate the total volume of air youre
  breathing per hour.
• Assuming that the air you breath contains 21
  oxygen, and the air you exhale contains 17
  oxygen, you can calculate your total oxygen
  consumption per hour.

• Example
• 15 breaths / minute
• 500ml air / breath
• 450 L air / hour
• (.21450) (.17450) 18 L O2 per hour

14
Possibilities with Metabolic Rate Measurements

• Effects of
• Age
• Exercise
• Size
• Temperature
• Time of Day

15
Possibilities with Metabolic Rate Measurements

• Effects of
• Age
• Exercise
• Size
• Temperature
• Time of Day

16
Possibilities with Metabolic Rate Measurements

• Effects of
• Age
• Exercise
• Size
• Temperature
• Time of Day

17
Possibilities with Metabolic Rate Measurements

• Effects of
• Age
• Exercise
• Size
• Temperature
• Time of Day

18
Possibilities with Metabolic Rate Measurements

• Effects of
• Age
• Exercise
• Size
• Temperature
• Time of Day