energy metabolism Flashcards
metabolism
the sum total of all chemical reactions occurring in an organism; the conversion of chemical energy into heat
2nd law of thermodynamics
in a closed system, the universe is always moving towards disorder however, animals are an open system
anabolic pathway
assembling of substances into complex molecules, requires energy
catabolic pathway
the breakdown of energy rich complex molecules into simpler ones, energy is released or stored as ATP or glucose
chemical energy
a form of potential energy, needed for atom reconfiguration
electrical energy
a form of potential energy in the charge speculation of molecules
heat
a form of kinetic energy that is formed by the random motion of all molecules; a degraded waste product in animals
mechanical energy
a form kinetic energy that is the energy of organized motion
work
a transfer of energy from one source to another
physiological work
a process carried out by organisms that increases order in the internal or external environment such as the breakdown of molecules or body movement, can only be performed by high grade energy
high grade energy
can perform physiological work; chemical, mechanical, electrical
low grade energy
cannot perform physiological work; heat or other degraded energy form converting high to low
ingested energy
energy found in the chemical bonds of consumed food
fecal energy
energy from food that is unable to be digested
absorbed energy
energy from food that is assimilated into the body and can be used; most of this is ultimately degrade to and released as heat
3 routes of absorbed energy
biosynthesis, maintenance, and external work; all result in some heat production as a result of inefficiency
biosynthesis
synthesis of body proteins and lipids; results in the accumulation of chemical energy in body tissues and is important for fat storage
maintenance
maintain the integrity of the organism as a whole; most expensive energy process; primarily internal work such as circulation respiration and gut motility
external work
mechanical work done outside the body such as eating and mating
is energy recycled
no, and this explains why animals are constantly consuming throughout their lives
metabolic rate
expressed as heat energy released per unit time or the rate of heat production; determines how much food an animal needs
direct calorimetry
method of measuring metabolism that involves the measurement of energy released as heat over a given time
indirect calorimetry
method of measuring metabolism that involves measuring metabolism from food intake and waste production
respirometry
form of indirect calorimetry involving the rate of gas exchange with the environment
material balance
form of indirect calorimetry that measures the chemical energy that enters and leaves the body
radioisotopes
method of measuring metabolism that involves injecting isotopes of O2 and H into an organism, then measuring the loss of body water with respect to the loss of O2; must be measured in 24hr increments
thermoconductivity
the ability to conduct heat
summit metabolic rate SMR
coldest temperature at which an organism can maintain its temperature without reaching hypothermia
respiratory ratios
respiratory quotient=(CO2 eliminated per unit time/ O2 consumed per unit time);RQ=1.0 for carbs, 0.71 for lipids, 0.83 for proteins; if the RQ is between any of these values we cannot determine what food is being used
factors affecting metabolic rate
age, gender, diet, hormones, physical activity level, and amount of lean muscle
Specific dynamic action SDA
the spike in metabolic rate that occurs immediately after a meal
absorptive state (fed)
ingested nutrients enter the blood, some are used to supply needs of the body in the net synthesis of proteins, glycogen, and fat
post absorptive state (unfed)
the digestive tract is empty and the available pool of nutrients in the blood decreases, there is a net degradation of proteins, glycogen, and fat
basal metabolic rate BMR
measured in thermal neutral zone, while fasting and resting, and should be at the lowest point of the circadian and circannual rhythms; ultimate resting rate (used in homeotherms)
standard metabolic rate SMR
must be measured at a certain temperature while fasting and resting (used in poikilotherms)
BMR + SMR
both are a stable rate of energy metabolism under conditions of minimum environmental and physiological stress and after fasting
temperatures affect on metabolism
temperature has a Q10 affect meaning that for every 10 degree change in temperature there is a 2-3x change in enzymatic activity and metabolic rate
maximum metabolic rate MMR
exercise induced metabolic rate, approximately 10x BMR or SMR
locomotion
the amount of energy required to move a unit of mass a unit of distance; small animals use more energy to achieve a given velocity than larger animals
what is the most energy dense substrate
fat with at least 2x as much energy as proteins and carbs
energy absorbed efficeincy
absorbed energy/ingested energy
gross growth efficiency
chemical bond energy growth/ingested energy
net growth efficiency
chemical bond energy added/absorbed energy; declines with age
