Test 3: Bioenergetics and growth Flashcards
What is metabolism?
Collective term for all the chemical reactions occuring in an organism’s body.
What is metabolic rate?
The total energy turnover in the body per unit time.
What is the energy budget?
energy in=energy out
What is the unit of energy?
joule (J)
- kilojoules (kJ)
- megajoules (MJ)
Does metabolic rate vary? If so, with what?
Yes, metabolic rate varies with:
- physical activity
- reproductive status
- lactation
- ambient temperature
How much does metabolic rate raise with an increase in body temperature?
A 1 * C raise in body temperature = 10% raise in metabolic activity
Which animals have higher metabolic rates? Young or old?
young animals
What hormones and which part of the nervous system increase metabolic rate?
Increase in metabolic rate:
- thyroid hormones
- sympathetic nervous system
What part of the nervous system is involved in “stressful” situations?
sympathetic nervous system
What happens with metabolic rates during prolongued periods of starvation?
metabolic rates gradually fall
What correlation does metabolic rate have with size?
inversely proportional
(metabolic rate decreases with an increase of body size) (exponential curve down)
What has a higher metabolic rate, rats or elephants?
rats!
they have smaller body sizes = highermetabolic rates
What is the main function of having a SA:V ratio?
maintaining body temperature
Why do smaller animals have higher metabolic rates?
- higher breathing rate
- higher heart rate
- eat more food per unit body mass
In what two ways can metabolic rate be measured?
DIRECT:
- calorimetry
INDIRECT:
- respirometry
- material-balanced method
What is calorimetry?
- direct method of measuring metabolic rate
- measures heat dissipation
What are the two indirect ways of measuring metabolic rate?
- respirometry
- material-balanced method
What is respirometry?
- indirect calorimetry method of measuring metabolic rate
- measuring O2 uptake
What is the material-balanced method?
- indirect calorimetry method of measuring metabolic rate
- measuring the chemical energy content of the organic matter that enters or leaves the animal’s body
What are the different levels of metabolism?
- basal metabolic rate (BMR)
- fasting metabolic rate
- maintenance metabolic rate
- field metabolic rate
What is BMR?
Basal Metabolic Rate:
- minimum metabolic rate required for maintenance of the basic life processes
What is fasting metabolic rate?
the metabolic rate of animals that are given the opportunity to stand, lie down, and preform normal body care.
What is maintenance metabolic rate?
When an animal eats exactly the aounts of feed required to maintain its body mass and does not produce milk, eggs, or movement.
What is field metabolic rate?
the average daily metabolic rate:
how much energy an animal is expending over a 24h period (under conditions such as: hunting, grazing, food searching, rest, reproduction, social interaction, etc.).
What are the most important contributions to the calculation of an animals energy requirement? What do such processes require?
- physical work
- deposition of lipids and proteins during growth and pregnancy
- production of eggs, wool and milk
each of these processes requires an extra supply of energy and a supply of appropriate nutrients.
What is an animals “energy requirement”?
sum of:
- maintenance requirement
- other function requirements (eg. milking, fetal growth, physical activity)
What does the amount of energy produced depend on?
the substrates eaten
What are the major biological macromolecules found in food?
- lipids
- proteins
- carbohydrates
Explain the relation of kcal/gram of the different macromolecules.
- lipids (9.3 kcal/gram)
- proteins (4.1 kcal/gram)
- carbohydrates (4.1 kcal/gram)
How are kcal converted into kJ?
1 kcal = 4.2 kJ
What is the respiratory quotient? How is it calculated?
The Respiratory Quotient (RQ) is the ratio between CO2 production and O2 uptake during steady state conditions.
RQ = CO2 expired / O2 consumed
What are the RQ values of the major food macromolecules?
- fatty acids (0.7)
- proteins (0.8)
- carbohydrates (1.00)
List the macromolecules in terms of increasing RQ values.
fats < proteins < carbohydrates
List the macromolecules in terms of increasing kcal/gram.
carbohydrates = proteins < fats
What happens when the RQ > 1?
anaerobic respiration
Do different substrates have different RQ values?
yes.
What does the measurement of RQ allow for?
Gain information about the source of energy an animal is using.
How can one compare the metabolism of animals under different conditions?
by comparing RQ
What can the RQ value inform one about?
- the substrate used
- wether it is respired under aerobic conditions
What increases during/after meal consumption?
- oxygen consumption
- heat production
What is the heat increment of digestion?
The increase in heat production of an organism during or right after meal consumption.
When is the heat increment of digestion highest?
After a protein rich meal.
Compare the heat increment of digestion of different species.
ruminants: >50% of the metabolized energy (due to fermentation in the forestomachs)
simple-stomach animals: 10-30%
What is the aerobic metabolic scope?
the ratio between:
- the highest aerobic metabolic rate that an animal can sustain over brief periods of time
- the maintenance metabolic rate
Around how many times can animals increase their metabolic rate during intense excersize?
25-35 times
(during fighting/racing)
Does utilization of energy in feed vary among animal species? If so, how?
Yes, the utilization of energy in the feed varies among animal species.
Carnivores:
- metabolizable energy represents more than 80% of gross energy in their natural diet
- digest meat and fat
Commercial Feed:
- carbohydrate rich (poorly digestable)
- lowers the metabolizable energy
Herbivores:
- cannot utilize as much energy
- diet rich in lignified plant material
Ruminants and Horses:
- 50% energy in feed is lost through feces, urine and methane gas (energy-rich fermentation)
- fed roughage
How is energy stored in the body? Why is it stored?
- stored as triglycerides
- in preperation for: periods when feed is limited/ energy requirements are elevated
What do deer have to aid them in the winter?
body stores of fat:
- energy source
- sufficient for maintenance requirements for 1-2 months
- winter: grazing is limited, feed has low digestability
What do migrating birds and mammals have to aid them in the winter?
- store fat as triglycerides
- energy for muscle activity
- triglycerides contribute to: distance and speed of migration
What do animals use the stored fat for during lactation?
- ATP production
- precursors for synthesis of milk fat
What is required for the growth and regeneration of an animal?
- steady supply of nutrients
- generation of ATP
- organic and inorganic molecule supply
How do animals grow during fetal life?
- transport of nutrients across the placenta
- nutrients contained in the egg (present since the egg was laid)
What are the most important hormones for the regulation of growth in fetal stages?
- insulin
- T3
What is insulin and T3 important for?
- hormone
- regulation of growth in the fetal stages
What compounds are important growth regulators after birth?
- growth hormones
- insulin-like growth factors
What is animal aging associated with?
- reduced appetite
- reduced metabolic rate
- reduced physical reserves
- reduced muscle mass
- reduced mental abilities
What happens to the number of cells (in the body) during aging?
decreases
State examples of diseases associated with aging.
- diabetes mellitus
- kidney diseases
- cancer
When does a herbivores aging process accelerate?
- teeth become severely abraided
- ability to digest feed becomes impaired
