Energy Metabolism

Question 1

what is calorimetry?

Answer 1

• measurement of heat production
• uses heat as an indicator of the amount of energy stored in the chemical bonds (C-H bonds)

Question 2

What are the Atwater values of CHO, fat and protein

Answer 2

4, 9, 4

Question 3

____ are less oxidized than _____ and _____

Answer 3

lipids; CHO; protein

Question 4

What are the factors that affect heat of combustion of fatty acids?

Answer 4

• chain length (long = releases more energy)
• degree of unsaturation (more double bonds = less energy released)

Question 5

What is the Heat Increment of Feeding

Answer 5

• energy used for the digestion, absorption, distribution and storage of nutrients
• used to determine net energy (net energy = metabolizable energy - heat increment of feeding)

Question 6

what are the three primary components to energy expenditure?

Answer 6

1. Basal metabolic rate
2. thermic effect of food (heat increment of feeding)
3. Physical activity energy expenditure
4. (thermoregulation)

Question 7

What is direct calorimetry? Is it practical and cost-effective?

Answer 7

• measures the heat a person generates
• expensive
• impractical

Question 8

What is indirect calorimetry? Is it practical and cost-effective?

Answer 8

• estimation of energy requirements by measuring O2 consumption, CO2 production and urinary nitrogen loss
• more practical
• more cost-effective

Question 9

What is the respiratory quotient? (including formula)

Answer 9

• provides info about energy expenditure and biological substrate being oxidized
• Ratio of metabolic gas exchange
• RQ = CO2 produced / O2 consumed

Question 10

How do you calculate basal metabolic rate using the respiratory quotient?

Answer 10

• O2/CO2
• find caloric value using the chart and ratio
• multiply the caloric value by the amount of gas to get kcal/h
• multiply by 24h