Animal Ecophys Flashcards
What is the specific dynamic action ?
Energy cost of digesting food
What is BMR ?
Rate of energy expended by a resting animal that is post absorptive and in a thermonuclear range.
What is RMR ?
Rate of energy expended by a resting animal of unknown absorptive rate.
What is SMR ?
Rate of energy expended by a resting animal at any given temp
What is FMR ?
Rate of energy expended by an animal at any given time
What are 2 techniques for measuring metabolism ?
Direct calorimetry
Indirect calorimetry
What does direct calorimetry measure ?
Total heat production
What 2 techniques are used in indirect calorimetry ?
Measurement from food intake & waste excretion
Respirometry- Measures amount of O2 used in oxidative process
What is the problem with measuring CO2 as a measure for MR ?
If energy store being utilised by the animal is different from prediction then CO2 has a massive error rate.
Give a brief description of TEB ?
Continuously record the behaviour of the animal
Measure how long the animal spent performing each behaviour
Assign energy values to each behaviour
Calculate the overall energy expenditure
What are the benefits and negatives of TEB ?
Benefits:
Technically easy
No technical equipment needed
Negatives:
MR of individual behaviours has to be known
Difficult to use accurately as other factors will affect the MR
Need to conform to standard operative temperature
Labour intensive
Give a brief description of DLW technique.
- Catch your animal
- Inject it with water that has been labelled with 18O (H218O) and Deuterium (2H2O)
- Allow the injectate to equilibrate with the body water pool
- Take a sample of body water e.g. blood
- Release the animal
- Recapture after a specified interval
- Take a final body water sample
- Analyse water samples using a mass spectrometer
With regards to DLW technique how is CO2 production calculated ?
The difference between rate of loss of 18o and 2H because 18o is lost as H218o and c18o2 wheres as 2H is lost as 2H2o
What are the drawbacks of DLW ?
- Only estimates the mean energy expenditure over the measuring period
- Not feasible to measure over short time resolution
- May have reduced precision in very active animals
- Can be problems trying to convert CO2 production to estimates of energy expenditure
What assumptions does the DLW technique use ?
- Body water remains constant
- Rates of water and CO2 flux remain constant
- Isotope labels only the body water (i.e they are not incorporated in tissues)
- Isotopes are lost only as CO2 and/or H2O
- Labelled or unlabelled CO2 and/or water does not enter the animal via respiratory or skin surfaces
Describe the heart rate technique procedure.
- Make calibrations
2.Oxygen consumption and fH recorded over time
Estimates of VO2 from fH compared with those measured via respirometry
3.fH monitor attached or implanted
4.fH recorded over time from free-living animals
5.VO2 estimated from fH recorded in the field using the calibrations
What are the benefits of HR technique ?
- Long periods of monitoring - potential for circa-annual estimates of MR
- Short time resolution
- Easy to integrate with behavioural data
- Can be used to estimate the MR of specific activities/behaviours
- Accurate estimates
- A physiological measure
What are the Drawbacks of HR technique ?
- Has to be calibrated with respirometry
- Calibration is species-specific
- Different muscle groups may have different relationships e.g. birds
- All the parameters have to vary systematically
- Measures only aerobic metabolism
- Technically very difficult to record in the field
Why might accelerometry result in an over estimate for energy expenditure ?
on moving water (may move device even though animal is still)
soaring on air currents
during periods of estivation/hibernation.
Why might accelerometry result in an under estimate for energy expenditure ?
post-absorptive
outside of its thermal neutral zone
growing rapidly
gestating or carrying an infant
What is phenotypic plasticity ?
Environment can directly induce changes in an individuals behaviours, morphology and physiology
Organs changing in migration is an example
What 5 parameters define migration ?
Persistent prolonged movement
Straightened course of movement
Undistracted by usual stimuli (e.g. food, mates)
Distinct departure and arrival behaviour
Reallocation of energy in advance of migration
What 4 adaptations do birds have that allows flight ?
- reduced numbers of bone sand pneumatisation (strong & light)
- provision of a keel on the sternum for attachment of the flight muscles
- Magnetoreception
- Highly developed cerebellum
What muscles do the bird use for the upstroke ?
supracoracoideus
Why are birds different to mammals in terms of fat metabolism ?
Birds use fat stores (Triacylgycerol) for high intensity activity such as flying instead of carbs
What physiological changes do birds like the ruff make before flight and during in stop over ?
Fat stores increase and so does pectoral mass
Liver stays in same ratio as pectoral mass
Why does pectoral muscle decrease in flight ?
Some energy needs to be derived from protein thus the muscle is metabolised
What physiological changes do birds like the bar tailed godwit make before flight and during in stop over ?
Fat stores increase and so does pectoral mass
Liver increases during stop over then decreases before they leave for flight. This is a proxy for the digestive tract. This reduces weight
When do some birds use protein as the main fuel for migration ?
Depends what food sources are at stop over points/ breeding grounds
Golden plover uses protein for spring migration.
What energy saving mechanisms do birds exhibit during flying ?
V flight formation
Bird at front has highest flap frequency and highest heart rate subsequently birds behind have lower flapping frequency and HR thus save energy
What is a eurythermic thermoconformer ?
An animal thats body temp is directly linked to the environment and can survive a large range of temps
What is a pokliotherm ?
Animal with changeable body temp.
What is the thermal nuclear range ?
The range of temp that endotherms dont have to metabolically thermoregulate
What is q10 ?
An indicator of temp sensitivity of a physiological process caused by a 10 degrees increase
Why are large crocodiles homeotherms but small crocodiles are poikilotherms ?
Large crocodiles have a lot more body mass than small crocodiles been it requires more energy to change their body temp thus they are less effected by the environment
What factors effect heat transfer ?
SA
Specific heat conductance
Temp difference
What are the morphological adaptations the desert snail shows to keep body temp low ?
Specialised shell shape that reflects heat and a shell that is too large for the snail which creates air currents thus keeping temp down.
What endothermy can be seen in ectotherms ?
Muscular activity such as shivering
Futile substance recycling (Metabolic pathway to produce heat)
What is heart rate hysteresis ?
The difference between the heating up rate and cooling down rate due to change in HR
How do bees maintain abdomen body temp ?
Counter current blood system
When does reverse hysteresis happen ?
Above 40 degrees HR increases during cooling to try and cool down faster
How do endothermic animal produce heat ?
Increase BMR Muscular activity Shivering Non-shivering thermogenesis Heat increment of feeding
Explain how marine iguanas use HR hysteresis ?
Increase HR when heating up thus vasodialation occurs and allowing more heat into the blood
Decrease HR when cooling down thus causing vasoconstriction so cooling down is slow
What adaptations do ectotherms show for temperature control ?
Behavioural: preferred temp, Shade
Morphological: Size, shell shape and size
Physiological: HR hysteresis
What is a benefit and negative of blubber when compared to fur ?
Heat loss and gain can be controlled when blubber is the insulator where as fur cannot be control. Fur is a better insulator when dry
What is a periarterial venous rete ? And what happens when animal is too hot
Artery surrounded by a network of veins with blood flowing in the opposite direction. When heat needs to be lost blood is directed to superficial veins instead of veins in counter current system
What are the 3 phases in fasting ?
Phase 1: use carbs
Phase 2: use fat and some protein
Phase 3: Metabolise only protein =starvation
Why do emperor penguins huddle ?
Allows them to lower body temp thus a lower MR therefor fat stores last longer
What are the 5 methods for reducing energy expenditure ?
Fasting Huddling Sleep Torpor Hibernation
How is torpor and sleep distinguishable ?
Animals in torpor arouse slower
What are 4 key aspects of torpor ?
- Not used during gestation due to drop in body temp
- Allows small animals to exploit habitats they normally couldnt exploit
- Large animals have shorter periods and less frequent periods of torpor
- Juvinile animals experience longer deeper torpors
Why does huddling reduce heat loss ?
Warms the local environment
Decreases the SA:VOL ratio
What are the key differences between hibernation and torpor ?
Hibernation does not occur in birds.
Topor does not occur in very large animals
Hibernation is much longer
Hibernation reduces BMR and RMR much more, down to 5%
What are the 3 definite and co-ordinated physiological changes that true hibernators under go ?
- Thermal dormancy: the ability of an animal to operate its biological functions at very low core body temp
- Behavioural suppression: The cessation of activity of many muscles, which depends upon the ability of the brain to override sensory inputs that would normally cause the animal to move.
- Metabolic inhibition: The ability of an animal to undergo episodic bradymetabolic changes such as the depression of energy related reactions
What are the 3 hibernation triggers ?
Ambient temperature
Food supply
Day length
What do some species of tortoise do to allow hibernation. 5 points
Lay down fat reserves Burrow below depth of frost Metabolic inhibition High arterial pCO2 Respiratory acidosis - implicated in metabolic depression
What do some species of snakes do to allow hibernation.
Retreat to hibernacula (Has to be humid) Store lipid in fat bodies and glycogen in the liver Critical factors in snake survival are: Lipid reserves Resistance to dessication low temperature due to link with MR
What is a common event of animals in hibernation ?
Brief periods of arousal causing a peak in body temp and thus hibernation is briefly interrupted.
What are the 6 characteristics of the hibernation state ?
Low metabolic rate and body temperature
Low water requirement
Maintenance of coronary blood flow
Respiratory acidosis
Reduction in transcription, translation, and protein degradation through inhibition
Increased expression of hibernation-specific genes to support lipid metabolism, gluconeogenesis
What is respiratory acidosis ?
The lower Tb of hibernating animals and the changes in the respiratory and cardiovascular performance lead to respiratory acidosis:
pH of arterial blood falls by 0.24–0.48
P CO2 is increased by a factor of 2.5–4.0
Hypoxic
But shift in OEC means that there is a higher affinity for O2
Why might hibernating animals have periods of arousal ?
Protein synthesis increases during these periods thus they are trying to repair tissue
Replenish water
Why do animals that utilise fat stores in hibernation not lose water via urination ?
No nitrogenous waste from fat metabolism
What sort of tissue is used in non shivering thermogenesis only in mammals?
Brown adipose tissue that has a large number of mitochondria
How does BAT differ from fat deposits ?
Contains lipid droplets
Large numbers of mitochondria
A good blood supply
ANS innervation
Describe the energy metabolism in BAT
Cold stimulates the release of nord adrenaline.
Under stimulation of NA, the rapid lipolysis is accompanied by the release of Acyl coenzyme A molecules.
The Acyl coenzyme A molecules possibly dislodge the purine nucleotides from the thermogenin and cause the mitochondria respiration to become uncoupled.
The uncoupling causes a proton flow that produces heat.
What protein in BAT contains the purine nucleotides that dislodge ?
UCP1 (THERMOGENIN)
What do bears do to allow them to stay dormant for so long ?
Go through hyperphagia (Force feed)
How do desert animals reduce their water loss ?
Impermeability
Tolerance to water loss – up to 48% in some desert toads
Concentration of excretory products – very hyperosmotic urine, or changing to uric acid
What do animals do to the air that they exhale ?
Cool the air down to regain the water that is lost during inhalation
What allows for concentrated urine ?
A long loop of henle in the kidney
What 3 different strategies do desert animals employ to thermoregulate ?
Evaders
Evaporators
Endurers
What are the 3 strategies for thermoregulation related to ?
Body mass
Evaders= Small like insects and small mammals
Evaporators= Medium like humans and dogs
Endurers= Large endothermic animals like camel
What are evaporators dependent on ?
Free source of water
How do evaporators cool the brain ?
Use of carotid rete system (mammals) or opthalmic rete (birds) for selective brain cooling
Why do desert animals such as the jack rabbit have large extremities ?
Allows them to radiate heat away from the body.
What strategies do endurers employ to allow survival ?
Have a well developed carotid rete which means they exhale reduced humidity air
Hyperosmotic urine
Inactive during the day
Adaptive hyperthermia
