Exam 2: Chapter 7: Energy Metabolism Flashcards
Two kinds of energy pathways
anabolic and catabolic
Energy metabolism consists of:
how animals get their energy, use that energy for their functions, and how they dissipate that energy from their bodies added together
The ____________ explains why animals need energy
second law of thermodynamics; isolated systems have no exchanges with their surroundings (neither matter or energy)
Animals need energy from the outside so they can….
have a stable internal organization
chemical energy
energy held in chemical bonds
when bonds are broken…
energy is released and is free to be used
electrical energy
comes from the separation of positive and negative electrical charges
electrical energy is present at all…
membranes
what are the 2 kinds of kinetic energy that animals use?
mechanical energy and heat
mechanical energy
organized motion
heat
molecular kinetic energy; random motion
most systems are inefficient due to
energy lost through heat
chemical energy can be used to do
all forms of physiological work
electrical energy can…….
mechanical energy can…..
put ions in motion
pump blood
heat can not do work in organisms, _________ is needed to have heat used for work
a temperature difference
efficiency of energy transformation=
(output of high grade energy) / (input of high grade energy)
efficiency of converting glucose to ATP
70% (30% is lost to heat)
3 major functions for energy use in animals
- chemical bonds in food are ingested energy
- biosynthesis is when ATP is used to make biomolecules
- inefficient as much energy is lost to heat
maintenance
keeping the body’s integrity, circulation, respiration, nervous coordination, gut motility, and tissue repair
generation of external work is done when
mechanical forces are applied to objects outside the body (riding a bike)
animal respiration
slow form of combustion
all tissues use ______ and produce _______
oxygen; heat
animals consume food in order to
break down chemical bond energy used for external work
metabolic rate
the rate at which energy is converted to heat (calories per unit time or watts)
metabolic rate is an indication of
the amount of food an animal needs; measure of the animals drain on the energy supplies of the ecosystem
direct calorimetry
a way of measuring the animals metabolic rate directly; done by measuring the rate at which heat leaves the body
respirometry
rate of respiratory gas exchange
material-balance method
measure the chemical-energy content of the organic matter entering and exiting an animals body
breakdown of glucose
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
2 factors with the greatest effect on metabolic rate
intensity of physical activity
temperature of the environment
other factors that affect metabolic rate
food, age, gender, time of day, body size, reproductive condition, hormonal state, psychological state
specific dynamic action (SDA)
by ingesting food, metabolic rate increases -> has to do with the calorigenic effect of ingested food: greater heat is produced with more calories consumed
proteins have a higher SDA than ______? What could this be related to?
- fats or carbs
- Could be related to the energy cost of nitrogenous waste production
diet-induced thermogenesis (DIT)
caused by prolonged overeating; a long-term increase i metabolic rate
basal metabolic rate (BMR)
used for homeotherms; animals that generate their own heat (mammals and birds)
standard metabolic rate (SMR)
applies to ectotherms; animals whose body temperature varies with the environment (like reptiles)
what is metabolic scaling?
the relation between metabolic rate and body size; generally, smaller animals have higher metabolic rates
resting metabolic rate
an allometric function of body weight in related species
how does metabolic rate relate to consumption of food in different species
small species, with higher metabolic rates, have to eat many times their body weight in order to maintain their high metabolic rate; large animals with low metabolic rates only consumes a fraction of their body weight
weight-specific metabolic rate
the rate at which organisms consume energy per gram of body weight
M=aWb
M is the whole metabolic rate and W is the body weight;
A and b are constants, b is most often 0.7 (resting metabolic rates of diverse animals)
exercise-induced maximum aerobic rate is…
10x greater than the BMR; a function of body weight
metabolism-size connection is important for both
physiology and ecology
heart size in mammals is roughly proportional to
body size
small animals have ______ heart rates in comparison to larger animals
higher
small mammals need more ________ per gram of body weight than larger ones
oxygen
why do small mammals have higher heart rates in comparison to larger mammals?
Smaller mammals require more oxygen per gram of body weight, but their hearts are no larger in relation to body sized when compared to larger mammals. Increased heart rate allows for increased oxygen delivery.
Small mammals have a _________ respiratory rate when compared to larger mammals.
higher; lungs are proportional to body size (like the heart) so a higher respiratory rate allows for increased oxygen intake
skeletal muscles of smaller mammals have ______ mitochondria than larger ones
more
smaller mammals due to higher metabolism accumulate more ________
toxins
fats are 2x as high in ________ when compared to proteins and carbs
energy density (energy values per unit weight)
migrating animals use ______ food sources
lipid dense
energy absorption efficiency
absorbed energy / ingested energy
absorbed energy
the energy actually available for use by the animal for metabolism
growth efficiency ________ with age
declines
important in agriculture
the brain accounts for ______ of resting metabolic rate
20% (1/5 of our food intake)
SDA can be…..
Chronic
BMR is related to
Environmental temp (thermoneutral zone) and whether the animal is fasting or resting
SMR is related to
Whether the animal is fasting or resting
When large numbers of animals metabolic rates are compared…..
Species similarities can be seen
