ch2 Flashcards
name 3 forms of energy
mechanical
chemical
heat
example of chemical energy in the body
storage of carbohydrates by forming glycogen for later use
example of mechanical energy
force production by skeletal muscle
energy efficiency in humans
20%: for mvt and work
80%: homeostasis (heat)
can ATP ever be completely depleted by exercising muscle
no (law of term dynamics)
always replenishing with 3 systems
how does the muscle respond to reduced ATP concentration
regenerates through
- creatine phosphate
- anaerobic glycolysis
- oxidative phosporylation
commonly used units of measure for energy in the field of nutrition
calorie
kcalorie
joule
kjoule
how do you go from kcal to joule
1 kcal- 4.2 kjoule
How is the energy content of food determined?
- Bomb calorimeter method (sealed container, calculates heat of food being burned)
- Atwater factor
(estimated with energy values of macronutrients)
energy content for carb
4kcal/g
energy content for protein
4kcal/g
energy content for fats
9kcal/g
energy content for alcohol
7kcal/g
how is energy expenditure measured by direct calorimetry
assessing the heat produced by the body during various activity.
process involves chamber or room designed to trap and measure the heat released by the body
what does indirect calorimetry mean
estimation of energy expenditure by measuring the amount of oxygen consumed and CO2 produced
so not using heat to dev energy expenditure
what is RER
respiratory exchange ratio
ratio of CO2 produced vs O2 consumed
what can RER tell us
which type of macronutrient our body is using for energy
substrate utilization vs RER
RER around & > 1 = carbs
RER around 0.7 = fats
RER btw 1-0.7 = mixed
RER equation
RER = VCO2/VO2
other ways to measure energy expenditure
- doubly labeled water
- HR monitoring
- accelerometer
- activity records
- energy equations
lbs to kg
lbs = 0.45kg
what is the energy balance equation
relationship between the energy you take in through food and the energy you expend through mvt and other bodily function
energy in = energy out
components of energy out
- resting metabolism (70%)
- physical activity (20%)
- thermic effect of food (10%)
what Is RMR
resting metabolic rate
amount of energy body needs for basic vital functions while at rest
