Energy and metabolism

Question 1

What do the components of our diet contain?

Answer 1

chemical energy that can be released during respiration to synthesise ATP.

Question 2

What is energy in food measured in ?

Answer 2

kilojoules per gram

Question 3

list the use of energy released from food

Answer 3

muscle contraction
synthesis of protein
maintenance of body temperature
active transport
transmission of nerve impulses

Question 4

What are ideal conditions?

Answer 4

Energy in balances energy out.

Question 5

What does having a healthy diet result in?

Answer 5

Reduction of risk of developing CVD of 30%.

Question 6

What is the BMR?

Answer 6

Basic metabolic rate. The total energy expended for basic body functions (60/70% of total energy output of sedentary adults).

Question 7

How is BMR measured?

Answer 7

Measuring heat release in a day or heat release per kg of mass in a day (to allow fair comparison between individuals).

Question 8

What are the basic body functions?

Answer 8

Breathing, 
contraction of the heart muscle, 
production of body heat, 
kidney function, 
cell metabolism.

Question 9

What are the standard conditions for someone’s BMR to be measured?

Answer 9

1. Completely rested before and during measurements
2. Fasted for at least 10-12 hours before measurements
3. In a thermoneutral environment (22-26) so no thermoregulation is required

Question 10

What are factors affecting BMR?

Answer 10

Body mass (more respiring cells in a larger person)
Body composition (lean muscle tissue is more metabolically active than fat per gram of mass)
Age (higher in children who use energy for growth, after 20 decreases 2% every 10 years)
Gender (higher in males because in average they have more lean and less fat tissue)
Nutritional status (diet with low energy intake will decrease BMR)

Question 11

What is the additional energy expenditure over BMR due to?

Answer 11

Physical activity,
colder climate (more heat loss so more energy spent on mantaining nbody heat),
Dietary-induced thermogenisis (energy for breakdown of food),
Composition of the diet (som food easier o break down than others),
Pregnancy and lactation (require energy for growth of tissues)

Question 12

Name a method of measuring energy expenditure.

Answer 12

Direct calorimetry.

Question 13

Describe direct calorimetry.

Answer 13

Measures the heat released from the body in an airtight chamber (which is insulated so does not allow heat loss). Person lives in the chamber for several days and heat is found by measuring T of water entering and exiting a heat exchanger.

Question 14

How does indirect calorimetry work?

Answer 14

There is a direct correlation between oxygen and energy consumption so oxygen consumption is measured over a period of time.

Question 15

What are the measurements that need to be taken for indirect calorimetry?

Answer 15

Volume of air and percentage of oxygen of inhaled and exhaled air so total volume of oxygen can be measured.

Question 16

What is the most indirect way of measuring energy expenditure?

Answer 16

By recording heart rate. It is based on correlation between oxygen consumption and heart rate.

Question 17

How is energy expenditure estimated through measuring heart rate?

Answer 17

Person’s oxygen consumption and heart rate have to be found at different exercise intensities, then oxygen use and energy expenditure correlated. energy expenditure is estimated through the two correlations.

Question 18

What are most of the fat molecules in our body stored as?

Answer 18

Saturated tryglicerides.

Question 19

What is he difference between direct and indirect calorimetry in measuring energy expenditure?

Answer 19

Direct calorimetry measures heat loss. Indirect estimates by using correlations to other forms of energy measurements.