Lecture 2 Flashcards
Basal metabolic rate (BMR)= (is defined as) rate of energy expenditure by what?
. Resting
. Post-absorptive
. Adult animal
. Within its thermoneutral range
When talking about post-absorptive BMR rate of energy expenditure why doesn’t it work when looking at snakes?
Post-absorptive is an increase of metabolic rate after a meal but for a snake an increased metabolic rate can take a few days so it is not post-absorptive until after a few days after a meal. So it is after effects of a meal
What can’t the BMR rate of energy expenditure be put to a juvenile animal?
Because they are growing and they have a metabolic component that is elevated because they juveniles
What is BMR? What is it also called?
The minimum energy used by an animal to maintain its body structure.
It is also called existence metabolism
Why is BMR a very important concept?
Because often we will compare the energetic rate of an animal by using its BMR e.g. comparing how many times the BMR an animal is using to do certain things such as running or flying so can look at that level of exercise
BMR is defined as ‘rate of energy expended by a resting, post-absorptive, adult animal and within its thermoneutral range’. What is the problem with this definition?
. Very few animals have a ‘thermoneutral range’ because an animal will very rarely be in this BMR
. Most animals don’t have a set temp, most animals are ectotherms and those animals that are endothermic have a thermoneutral zone
. The fourth point doesn’t apply to any ectotherms
Define standard metabolic rate (SMR)
Rate of energy expended of a resting, post-absorptive animal at a given body temp (so can compare animals that are at the same temp)
(Can only really be done in the laboratory environment where you can control everything)
Define resting metabolic rate (RMR)
Rate of energy expended by a resting animal of unknown absorptive state (what is the lowest metabolic rate of an animal that you will see in the wild. (Can only really be done in the laboratory environment where you can control everything)
Define field metabolic (FMR)
Rate of energy expended by a free-living animal. (Animals in the wild aren’t going to be resting all the time as they need to go out and find food and a mate etc. Therefore their metabolic rate is going to go up and down/ fluctuate other factors
Define average daily metabolic rate (ADMR)
Average rate of energy expenditure over an entire day (24h) regardless of activity levels (most animals work on a 24h cycle so it take into account these fluctuations. Active and resting phase. So can compare different species at different times of year or compare their average daily metabolic rate
What are the two types of laboratory techniques for measuring metabolism?
. Direct calorimetry
. Indirect calorimetry
Explain the laboratory technique for measuring metabolism direct calorimetry
Is a measure of an energy- heat produced by an animal, so its metabolic rate
. Measures the total heat production
. Most accurate (measures the most heat produced by an animal so therefore its metabolic rate .)
. Technically very complex
Explain the laboratory technique for measuring metabolism indirect calorimetry
. Measurement from food intake and waste excretion (because we know that energy cannot be made or destroyed but just changed from one form to another
. Respirometry
Describe how the laboratory technique for measuring metabolism direct calorimetry works
Is a chamber that surrounds the animal that is surrounded by ice- the heat of the animal will melt the ice and over a period of time there will be water collected from the device and if you measure the amount of water that is produced and the time over which it is produced so can measure how much energy was put in to melt the ice and therefore work out the metabolic rate of the animal
Who were the first people to use direct calorimetry?
Lavoisier and Laplace to measure heat production of a guinea pig (17kJ to melt 1kg of ice)
What does measurement from food intake and waste excretion do?
Calculates the difference between the energy value of food taken in and the energy value in the faeces and urine (C-(F+U))
What animals can you not do the measurement from food intake and waste excretion to calculate metabolism on?
Cannot be used in growing animals
When is the measurement from food intake and waste excretion accurate for calculating metabolism?
Accurate only after long periods of measurement
What does respirometry measure?
Measures the amount of oxygen used in oxidative processes
What does respirometry assume?
Assumes no anaerobic metabolism because it is measuring the oxidative processes, always a component of anaerobic processes at an instantaneous level
What is the most used technique for calculating the metabolic rate of an animal?
Respirometry
Why are fat stores good when not eating for long periods of time?
. The energy density of fat is about 2 times that of carbohydrates and protein and energy about the same
. Fat has a very high energy content for a given mass therefore it is a good store
What is Kleibers law?
Metabolism equals mass raises to the 3 quarter power
