Lesson 2- Defining and Measuring Energy Flashcards
What is Energy?
Ability to do work (mehcnaical energy)
- Other types of energy include chemial and heat energy)
What is energy expenditure?
energy/time
What type of energy am I referring when talking about calorie?
Heat energy
What is a calorie?
Energy needed to raise 1 g of water by 1degree celsius
Is c or C expressed on food labels?
Calorie is a kcal and calorie is a single calorie
What is a Joule?
Energy required to move a mass of 1 g at a velocity of 1 m/s
What is 1 cal equal to in J?
1 cal = 4.186 J
What type of energy does a J measure?
Chemical Energy
What type of energy does a calorie measure?
heat energy
What is the first law of Conservation of Energy?
In a closed system, energy cannot be created or destroyed, it is only transformed from one type to another
Where does the 20% of energy go to in humans? and the 80%?
20% –> goes for movement and work
80% –> goes to maintaing homeostasis
How does ATP provide us with energy?
We get energy off of it through a very rapid one step chemical reaction where a phosphate group is removed
What catalyst is responsible for removing the phosphate group?
It is the enzyme called ATPase
Is ATP relevant for the relxation of the muscle and the firce production?
YES, for both
What are the 3 systems for ATP use?
-Creatine phosphate
-Anaerobic glycolysis
-Oxidative phosphorylation
What is the unit of measure for energy?
It is Joules (J)
What is a bomb calorimeter?
its a device that determines energy by the amount of heat produced.
How is a bomb calorimeter used?
The “bomb” is a
metal container in which the food sample is burned in a
pressurized, pure oxygen atmosphere. It is constructed
to withstand high temperature and pressure, and it is
surrounded by a water bath that is insulated from outside temperature changes. As the food sample burns,
the temperature change in the surrounding water bath
is recorded with a sensitive thermometer to determine
the thermal energy of the food.
What does direct calorimetry indicate and indirect calorimetry indicate?
Direct calorimetry - heat energy measured through change in temperature
Indirect calorimetry - looks at oxygen consumpotion and CO2 production to energy expenditure and heat production
What are the most commonsly used systems ?
Open cicuit - in which the subject breathes in ambient room air and is not confined to breathing the air within a sealed environment.
What are the conditions that need to be met for meauring the REE (resting energy expenditure)? (8 conditions)
- Resting supine position >30 mins
- No alchol for >48hrs
- Fasting >12hrs
- Nicotine >1hr
- Caffeine >4 hrs
- Exercise >24-48hrs
- Normal acid-base balance
- Quiet, dark, thermoregulated room
What is RER?
Respiratory exchange ratio
What is the formula for RER?
RER = VCO2/VO2
When would you have an RER > 1.0?
- Hyperventilating
-Lipogenesis
What is the RER for proteins, carbs and lipids?
Carbs RER: 1.0
Lipids RER: 0.7
Protein 0.8
Frequently used methods for estimating energy intake? (3)
- Food diary
- Food frequency questionnaire
- 24 hr recall
Self reported food intake (4)
1- need accruate recordings
issues with this:
- portion sizes must be estimated correctly
-food intale is typically underestimated (12-16% up to 20%)
erors in data entry can occur
How much % is the energy expenditure of a sedentary person?
70%
Thermic effect of food accounts for how many %?
10%
How mcuh does physical activity account for?
20%
Which of these is mostly readily influenced in terms of energy expenditure?
Physical Activity
Factors affecting resting metabolic rate? (Influence not under voluntary control)
Gender
Genetics
Age
Body size (Height)
Thyroid hormones
Factors affecting resting metabolic rate? (Substantial influence under some voluntary control)
Starvation
Amount of fat free tissue
Factors affecting resting metabolic rate? (Subtle or temporary influence, under voluntary control )
Exercise
Environment temperature
Ascending to high altitude
Caffeine intake
What are the activity factors?
-Sedentary (little to no exercise): 1.2
-Lightly active (1-3 days/week): 2.375
-Moderately active (3-5 days/week): 1.55
-Very active (6-7 days/week): 1.725
-Extra active (physical job 2x training): 1.9
What are 2 factors that can decrease the RMR? (resting metabolic rate)
- Starvation
- Age
What is the greatest influences on RMR ?
amount of body mass, specifically the free fat mass
