LT1 Metabolism Flashcards
What does thermodynamics tell us?
Whether a process is energetically favourable
What is the 1st law of thermodynamics?
Energy is neither created nor destroyed
It is converted from one form to another
(total energy before and after conversion is the same)
What is the 2nd law of thermodynamics?
When is energy is converted from form to another, so of that energy becomes unavailable to do work
No energy transformation is 100% efficient
Usable energy (free energy) and Unusable energy
What is the equation for free energy change?
Energy of products - Energy of reactants
What is the free energy change of food?
Food intake
Release of nutrients by digestion
Energy product = stored energy - (heat loss + excretion)
What is the energy product gotten from food?
Stored energy - (heat loss + excretion)
Reactions involve change in what?
Enthalpy = heat content
Entrophy = randomness; disorder
(it takes energy to impose order on a system, otherwise it will be randomly arranged or disordered)
What is the most important change involved in reactions?
Free energy
ΔG = ΔH - TΔS
T = temp in Kelvin
What did Sanctorus 1614 discover?
Most food lost through “insensible perspiration”
Weighted himself before/after daily activities
What did Boyle 1670 discover?
Established that a “vital gas” is required for combustion and to sustain life
Candle flame extinguished as gas consume in a sealed container
What did Mayow discover?
First calorimeter prototype
What did Priestly/Lavoisier 1774 discover?
Oxygen identified as “vital gas” and its role in respiration studied
Indirect calorimtery = volumetric measurement of O2 consumption at reat, after meal and exercise
What did Regnault/de Reiset 1849 discover?
Introduction of closed-circuit calorimetry
Template for precise application of thermodynamic principles to human calormetry
What did Kleiber 1947 discover?
Metabolic rate scales with body mass to the 2/3 powering in animals
Evolutionary drives, which link metabolic needs to body plant & lifestyle
What did Keys 1950 discover?
Minnesota Expt
Establishes common measurements that are used today to monitor metabolic health
What is the Calorie?
Unit definition of ENERGY use
Heat input required to raise the temp of 1L of water by 1 degree Celsius
What do Calories link?
Mass (kg)
Energy (J)
Force (N)
How does Closed Ciruit Calorimetery work?
Organism sealed in container
O2 added and CO2 absorbed
Temperature changes recoreded
How was temperature change measured
in Closed Circuit Calorimetery?
ΔT determined by change in heat required to maintain constant temp
How was change in oxygen measured in Closed Circuit Calorimetery?
ΔO2 consumption determined by manometer change needed to maintain even pressure in the system
How was carbon dioxide measured in Closed Circuit Calorimetery?
ΔCO2 produced determined by change in mass of soda-lime
Who came up with Calorimeter for Man?
Atwater & Benedict 1965
What is basal metabolic rate (BMR)?
Minimal caloric requirement measured in an AWAKE individual in absolute physical and metal rest after 12h fasting and at env temp of 22.5 degrees C
What 8 factors affect BMR?
Gender, Age, Diet, Genetics
Exercise, Body fat, Body mass
THYROXIN
How does gender affect BMR?
Males have a higher BMR by 10%-15% than females
How does age affect BMR?
Drops 2% by decade
How do genetics affect BMR?
Depends on mitochondrial phenotype
How does diet affect BMR?
Restrictive diets can cause BMR to fall 20%
How does thyroxin affect BMR?
Increased thyroxin increases BMR
What does thyroxin do?***
Thyroxine stimulates the release of energy from stored nutrients in all cells of the body.
This speeds up cellular metabolism, which in turn speeds up growth and development.
How does body fat affect BMR?
More exercise decreases body fat %
Decreased body fat % increases BMR
How does body mass affect BMR? ***
Kleiber’s Law = metabolic rate scales 3/4 power of body mass
What is Kleiber’s law? ***
Metabolic rate scales 3/4 power of body mass
What is total daily energy expenditure composed of?
BMR = 60%-70%
Thermic effect of food = 10%
Activity thermogenesis = 20% -30%
What is activity thermogenesis?
Spontaneous physical activity (SPA)
Non-exercise actiivty thermogenesis (NEAT)
What factors set the boundaries for ATP production?***
What is the predictive equation for BMR of male?
66.5 + (13.8 x mass[kg] + 5xheight[cm] ) - 6.8xage [years]
What is the predictive equation for BMR of female?
665.1 + (9.6 x mass[kg] + 1.9xheight[cm]) - 4.7xage [years]
What are BMR units?
kcal per day
