metabolism Flashcards
define metabolism
the sum of all chemical reactions occuring in an organism
what are anabolic pathways responsible for
assembling simple molecules into complex ones, requiring energy
what are catabolic pathways responsible for
breakdown of complex molecules into simple ones, releasing energy
what is the first law of thermodynamics
total energy input must equal energy output
what are the 2 main energy output types
somatic and maturity maintenance
what is energy used for in somatic maintenance
existence e.g. growth
what is energy used for in maturity maintenance
reproduction
what controls the appetite and satiety centres
arcuate nucleus (ARC)
what are the appetite suppressors and stimulators
NPY - stimulator
MSHs - suppressor
what controls mid / long term energy balance
leptin (fat storage) and insulin inhibit NPY release
what controls short term energy balance (3)
CCK intestinal secretion signals satiety
PPY (intestine) inhibit NPY
Ghrelin (stomach) stimulates NPY
what is basal metabolic rate (BMR)
stable rate of energy metabolism in endothermic animals under minimal environmental and physiological stress
what is standard metabolic rate (SMR)
an ectotherms resting metabolic rate at a given body temperature
what is aerobic metabolic scope
the metabolic range of which an animal is capable. The ratio of maximum sustainable metabolic rate (MMR) to BMR / SMR
2 ways to measure metabolic rate and how do they do it
direct calorimetry - measure heat change
respirometry - measures oxygen in and carbon dioxide out
what is the issue with how we measure metabolic rate
they assume energy generated = oxygen used but different fuels liberate different amounts of energy
what is the equation for the respiratory quotient
Rq = rate of CO2 production / rate of O2 consumption
what is the respiratory quotient for:
2C51H98O6 + 145O2 -> 102CO2 + 98H2O
145 / 102 = 0.7
what is the Rq for carbohydrates
1
what is the Rq for fats
0.7
what is the Rq for proteins (usually)
0.8
list 6 things that can effect energetic demands / metabolic rate
size and mode of thermo-regulation
locomotion
development
reproduction
circadian rhythm
stress
how does locomotion impact metabolic rate - small vs large animals
larger animals have lower overall cost of transport per gram of body mass due to inertia
how does reproduction impact metabolic rate
K selected species require more energy per offspring
how does Briceno’s paper support circadian rhythms impacting metabolic rate
nocturnal lobsters have higher metabolic rate at night
How does Briceno’s paper show stress impacting metabolic rate
lobsters exposed to karimone (squid which would eat lobster)
those exposed to stressor decrease metabolic rate as they are hiding
what happened when temperature was increased in the lobster experiment
energetic trade-off’s - the lobsters didn’t hide as they could not afford to. They had higher energetic demands so needed to continue eating despite threat
what happens to oxygen conc in ectotherms as temperature increases
oxygen conc. increases until proteins are denatured
what happens as temperature increases in endotherms
it controls it’s own temperature as long as conditions stay on the euthermic zone
outside the ranges of the euthermic zone the organism doesn’t function
