W2 - More Readings Flashcards
Antioxidants
Compound that can donate electrons to oxidised compounds = puts them in a more reduced (stable) state.
What do oxidised compounds tend to be?
Highly reactive
Give an example of a dietary antioxidant
Vitamin E
What type of vitamin are niacin and riboflavin
B-vitamins
What do niacin + riboflavin do?
Assist dehydrogenase enzymes by transferring H atoms from energy-yielding compounds to O2 in metabolic pathways.
What is niacin when it functions as a coenzyme?
NAD (oxidised form)
NADH (reduced form)
What is the result of NAD+ being oxidised
NAD+ –> NADH + H+
What is riboflavin when it functions as a coenzyme?
FAD (oxidised form)
FADH2 (reduced form)
Define energy expenditure
EE (kJ or kcal) per unit of time to produce power
What is the imperial system of expressing energy?
Calories
What is the metric system of expressing energy?
Joules
Define gross efficiency
Ratio of total work to energy expended
Define delta efficiency
Change in EE per min rel. to the change in actual work accomplished per min
What does the energy content of CHO depend on?
Its type
Arrangement of atoms in it
Define coefficient of digestibility
% of food energy that’s absorbed
Define work efficiency
Baseline of the energy cost of unloaded work
Methods to measure human energy expenditure
Direct + indirect calorimetry
Closed-circuit + open-circuit spirometry
Douglas bag technique
Breath-by-breath technique
Portable spirometry
Doubly labeled water
Labeled bicarbonate
HR monitoring
Accelerometry
Observations, records of PA
Why was the direct calorimeter suit made?
To overcome some of the practical problems from the direct calorimeter chamber
What does the direct calorimeter suit consist of?
Long plastic tube through which a known amount of H20 flows.
Tube touches skin to absorb body heat.
Problems with the direct calorimeter suit
May impair movement
What can be used to measure O2 uptake + CO2 production
Closed-circuit spirometry
Open-circuit spirometry
What is the Closed-circuit spirometry used for?
To measure resting EE
How does Closed-circuit spirometry work?
Spirometer prefilled w/ 100% O2
Subject breathes through mouthpiece into spirometer
W/ each inspiration some O2 is consumed.
Expired gas is passed back to spirometer, CO2 trapped in filter.
Residual O2 in chamber is avail. for next inspiration.
O2 in spirometer ⬇️
Change in vol. is measured
O2 uptake + EE is calculated.
When is Closed-circuit spirometry useful?
In resting cond.
Not during exercise
What does breath-by-breath systems allow?
Observe time course of changes in various ventilatory variables.
Positives for breath-by-breath systems
Analyse every breath
Able to register rapid changes
Gives instant fb
When is doubly labeled water only suitable for?
LT (days/weeks) estimation of EE
Labelled bicarbonate
Infusion of labelled bicarbonate at a constant rate.
Reaches equilibrium w/ bodys CO2 pool.
After, any change in bodys CO2 prod will result in change in % of labelled CO2.
Equation for EE (kcal) using an accelerometer
Distance covered (km) x body mass (kg)
Equation for EE (kJ) using an accelerometer
Distance covered (km) x body mass (kg) x 4.184
