Week 3 Fuel Homeostasis Module Flashcards
1 Calorie=
1000 calories; 1 kcal; 4,180 J; 4.18 kJ
what is direct calorimetry?
the heat released from hte total physical combustion of a food
rank the following macromolecules in terms of energy released when burned
Fat>Carbs=Proteins
why does fat release more energy than carbs or porteins when burned
fats are highly reduced (all C-H bonds). this means their complete oxidation will release more total energy
which macromolecule is the most efficient fuel in terms of calories produced/amount of O2 consumed?
carbohydrates
what is indirect calorimetry?
estimates caloric yield by measuring the oxygen consumed, CO2 produced and nitrogen eliminated
how do you calculate the amount of protein in the body from nitrogen elimination?
16% of protein is nitrogen, multiply the nitrogen excreted by 6.25
what is a calorie?
energy needed to raise temperature of one gram of water from 15 to 16DC
what is the respiratory quotient
the ratio of the volume of CO2 produced: volume of O2 utilized
what is the value of RQ for carbs, protein, fat?
Carbs: 1
protein: .8
fat: .7
what will RQ values tell us about feul usage?
the closer the RQ values is to the RQ of a certain fuel source (carbs, protein, fats) the more that fuel source is being used.
Ex; if a runner has an RQ of 0.97 at the beginning of a race and then 0.79 towards the end of the race what can be said about his fuel source?
at the start carbs were a major fuel source, towards the end he was using lipids (proteins generally only come into play during starvation)
what explains how blood glucose levels are maintained druing exercise?
gluconeogenesis is occuring as well as tapping into glycogen stores
As exercise duration progresses from 0 to greater than two hours, what is the change seen in where our bodies are getting energy?
glycogen in skeletal muscle is used first–>glycogen within the liver is used–>fatty acids are oxidized
what occurs after glycogen stores are depleted and gluconeogenesis is stopped?
the brain shuts down because glucose is its only form of energy
what is energy density?
the amount of energy in a gram of a food item
in what three ways do our bodies expend energy?
thermic effect of food energy needed to process food), physical activity (energy needed to move), basal metabolism (energy needed for basic life functions)
what percent of out energy goes to basal metabolism?
50-70% (BIGGEST ENERGY EXPENDATURE OF BODY)
how is BMR (basal metabolic rate) related to body mass?
BMR is most closely related to lean body mass (muscle), as lean body mass increase the BMR increases
what is the BMR when asleep?
10% decrease
how much of out energy goes to processing of food (thermic effect of food):
10%
how much of our energy goes to physical activity
15-30%
what is the difference between resting metabolic rate and basal metabolic rate?
RMR is easier to measure, does not require fasting, and only requires a brief resting period
what is the resting energy expenditure?
the resting metabolic rat over 24 hours
what is the BMR of males? females?
males: BMR= 1.0 kcal/hour/kg
female: BMR=0.9 kcal/hour/kg
how does age, sex, growth, body weight, stress impact BMR
increased age decreases BMR, males have higher BMR, increased weight/height increases BMR, stress increases BMR
what is total energy expenditure?
the total (thermogenic effects of food+exercise+basal metabolism) energy used by the body
what are the steps for determining total caloric needs of the body?
- calculate basal energy needs when awake: BMR (kcal/kg/hr)weighthours awake
- calculate basal energy need when asleep: ten percent decrease in BMRweighthours asleep
- calculate energy expenditure during exercise Xkcal/kg/hrweighttime
- calculate thermic effects of food: 10% caloric intake until this point
- add them together
