Bioenergetics Flashcards
Define “nutrient”
Any dietary element the body is able to use to help meet a biochemical requirement for health
Define “esential nutrient”
A nutrient that is essential for health
2 reasons why a nutrient may be “non-essential”
- Another nutrient is able to serve the same metabolic function
- The body can synthesize this particular nutrient from a different one
4 nutrient classes that provide chemical energy
- Lipids
- Carbohydrates
- Proteins (amino acids)
- Ethanol
3 levels of organization for the functions that keep you alive
- Cellular
- Whole body
- External work
Define the cellular level of organization for the functions that keep you alive (5 points)
- Maitnenance of trans-cellular ionic gradients
- Transport of substrate molecules
- Biosynthesis and selective biodegradation
- Creation, transmission, sensing and response to neural and hormonal signals
- Whole cell turnover
Define the whole body level of organization for the functions that keep you alive (7 points)
- Internal work of moving the blood through the circulation
- Respiration
- Formation and excretion of urine
- GI digestive and absorptive functions
- Body temperature regulation
- Maintenance of body posture and position
- Muscular activity not involving external work
Amount of chemical energy converted to heat per hour by a 70 kg person at rest
Approx. 85 kcal/h
Typical rate of energy flow through the body
2500 kcal/day
Amount of ATP the body must synthesize and hydrolyze and what this means
- 65 kg of ATP/day –> 45 g/min
- Body contains only about 45 g of ATP –> complete ATP turnover every minute
Define the Pasteur effect
Accelerated glycolysis under anaerobic conditions
Why is anaerobic glycolysis must less efficiency than the aerobic pathway?
It generates NADH, but WITHOUT oxygen present, it cannot be re-oxidized back to NAD+ –> accumulation
Define lactic acidosis
The buildup of lactic acid in tissues and blood under anaerobic consitions (oxygen debt)
How to measure the maximum capacity to do physical work
Measure maximum oxygen uptake rate (VO2 max)
Where is surfeit carbon stored?
Adipose tissue as triglycerides
Define direct calorimetry
Measurement of the body’s rate of heat production in order to determine its rate of oxidation
Equation for glucose oxidation
6O2 + 6[C-HOH] = 6CO2 + 6H2O + HEAT
Equation for long-chain fatty acid oxidation
3/2nO2 + [-(CH2)-]n = nCO2 + nH2O + HEAT
Give the 4 nutrient classes in order of the heat they produce when they are oxidized
- Triglycerides (9kcal/g)
- Ethanol (7 kcal/g)
- Carbohydrate (4 kcal/g)
- Protein (4 kcal/g)
Define indirect calorimetry
The inference of the rate of fuel oxidation by measuring oxygen consumption
Conversion factor relating oxygen consumption to heat production
Heat production (kcal/min) = 4.8 x Oxygen consumption (L/min)
Define the law of entropy in the scope of bioenergetics
Approximately 5% of energy released when a fuel is oxidized is obliged to be converted to heat (the rest is free energy)
Describe the distribution of free energy from oxidized fuel
- One half –> new P bonds in ATP (and other high-energy substrates)
- One half –> Wasted as heat in the metabolic steps leading to ATP synthesis
3 major determinants of energy flow
- Basal metabolic rate (BMR) or resitng energy expenditure (REE)
- Thermic effect of food
- Energy expended for activities above basal
Define BMR or REE
The rate of fuel oxidation while a person is quietly lying at rest and simply “staying alive”
The rate of heat production of a person who is physically and mentally comfortable, relaxed, and reclininc in a thermo-neutral environment several hours after the previous meal
Define the thermic effect of food
The small amount of heat released to deal with the food consumed in meals
4 situations where metabolic stress can occur
- Tissue samage
- Inflammation
- Severe infection
- Certain metabolic diseases
Define metabolic stress
Increase in the body’s metabolic traffic, use of ATP and heat production
Define fever
Increase in the body’s core temperature from above its normal set point of 37 degrees C
3 ways the body achieve a higher set point temperature
- By ozidizing fuel faster to generate more heat
- By inducing shivering
- By sending a message to the conscious brain that makes it feel uncomfortable cold –> put on sweater and blankets
Proportion of total daily expenditure by REE in sedentary individuals
2/3
Rule of thumb to predict a person’s REE
For a non-obese adult:
- REE = 1.0 kcal/kg body weight/hour (man)
- REE = 0.95 kcal/kg body weight/hour (woman)
Compare the REE of an obese person to an average person
Higher than “normal” (i.e. the REE they would have or will have after they eliminate their excess fat and achieve a normal body composition)
Proportion of the total energy in the food consumed that is occupied by the thermic effect of food
8%
2 categories of physical activity
- Deliberate formal professional or recreational exercise
- Non-exercise activity thermogenesis (NEAT)
Define NEAT
The changes in posture and movement that occur in the course of the normal routines of daily life
Define METS
A quantification of the energy expenditure associated with different physical acitivities. One MET = a particular individual’s REE (higher = more effort)
Rule for the total daily energy expenditure of a normal sedentary person
1.5 x REE
Reason for body weight fluctuations throughout the day
Increases or decreases in ECF volume associated with changes in:
- Fluid (and salt) intake
- Urinary excretion
- Sweating
- Evaporation
Reason for large, sustained changes in body weight
A change in BCM and adipose tissue mass
4 classic vital signs
- Body temperature
- Blood pressure
- Heart rate
- Respiratory rate
Define temperature
The measure of kinetic energy of the molecules in a substance
2 factors to determine the amount of heat required to raise the temperature of an object
- The object’s mass
- The amount of energy needed to overcome the intermolecular forces that restrain the vibrations of its molecules
What does an elevated body temperature imply?
The body is generating heat (and transferring it out of the body) faster than normal
2 determinants of the specific rate of fuel oxidation associated with a specific body temperature
- The rate heat is produced (i.e. rate of fuel oxidation)
- The rate heat is dissipating from the body
4 factors determining the rate of heat dissipation from the body
- The patient’s surface areas
- Thermal insulation (skin, subcutaneous fat, clothing, blankets)
- Ambient room temperature and humidity
- Capacity to perspire
A direct regulator of REE
Thyroxin
Effect of anticholinergic drugs on perspiration and the significance of this fact
Inhibition of perspiration –> characteristic clinical sign of poisoning = fever
Explain why fever occurs in toxic doses of aspirin
Uncoupling of oxidative phosphorylation –> release free energy of ATP as heat
Approximate rule for predicting a patient’s metabolic rate
Under constant conditions of heat dissipation, each 1 degree C increase in body temperature implies an increase in the rate of fuel oxidation by a factor of 1.1
